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Amended Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) and Recovery Strategy for the Non-pollinating Yucca Moth (Tegeticula corruptrix) and the Five-spotted Bogus Yucca Moth (Prodoxus quinquepunctellus) in Canada [Proposed] - 2017

Part 1 - Federal Addition to the Alberta Soapweed and Yucca Moth Recovery Plan 2012-2022, prepared by Environment and Climate Change Canada.

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress five years after the publication of the final document on the SAR Public Registry.

The Minister of Environment and Climate Change is the competent minister under SARA for the Soapweed, Yucca Moth, Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth and has prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. To the extent possible, it has been prepared in cooperation with the Province of Alberta and Agri and Agri-Food Canada as per section 39(1) of SARA. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub-sections 41(1) or (2)). The Province of Alberta led the development of the attached recovery strategy for Soapweed and Yucca Moth species (Part 2) in cooperation with Environment and Climate Change Canada.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment and Climate Change Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of Soapweed, the Yucca Moth, the Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth and Canadian society as a whole.

This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment and Climate Change Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

The recovery strategy sets the strategic direction to arrest or reverse the decline of the species, including identification of critical habitat to the extent possible. It provides all Canadians with information to help take action on species conservation. When critical habitat is identified, either in a recovery strategy or an action plan, SARA requires that critical habitat then be protected.

In the case of critical habitat identified for terrestrial species including migratory birds SARA requires that critical habitat identified in a federally protected area Footnote 1 be described in the Canada Gazette within 90 days after the recovery strategy or action plan that identified the critical habitat is included in the public registry. A prohibition against destruction of critical habitat under ss. 58(1) will apply 90 days after the description of the critical habitat is published in the Canada Gazette .

For critical habitat located on other federal lands, the competent minister must either make a statement on existing legal protection or make an order so that the prohibition against destruction of critical habitat applies.

If the critical habitat for a migratory bird is not within a federal protected area and is not on federal land, within the exclusive economic zone or on the continental shelf of Canada, the prohibition against destruction can only apply to those portions of the critical habitat that are habitat to which the Migratory Birds Convention Act, 1994 applies as per SARA ss. 58(5.1) and ss. 58(5.2).

For any part of critical habitat located on non-federal lands, if the competent minister forms the opinion that any portion of critical habitat is not protected by provisions in or measures under SARA or other Acts of Parliament, or the laws of the province or territory, SARA requires that the Minister recommend that the Governor in Council make an order to prohibit destruction of critical habitat. The discretion to protect critical habitat on non-federal lands that is not otherwise protected rests with the Governor in Council.

Acknowledgments

The federal component of this recovery strategy (Part 1) was written by Medea Curteanu (Environment and Climate Change Canada [ECCC]). An earlier draft was prepared by Julie Pearce (Pearce and Associates Ecological Research). Candace Neufeld (ECCC) provided extensive species information and guidance throughout the development of the document. Donna Hurlburt (Consultant), Dan Johnson (University of Lethbridge) and Cathy Linowski (Medicine Hat College) are acknowledged for providing species data and information. The Alberta Environment and Parks and Alberta Conservation Information Management System (ACIMS) provided updated element occurrences. The cover page photos were generously provided by Gord Court, Olaf Pellmyr, and Donna Hurlburt. Sandi Robertson and David Johns (Alberta Environment and Parks), Bill Houston (Agri and Agri-Food Canada), Greg Wilson, Mark Wayland, Victoria Snable, Kim Borg, Marie-Andree Carriere, and Paul Johanson (ECCC) have reviewed the document and provided valuable comments. Lynne Burns has provided extensive GIS assistance and created the critical habitat map.

Additions and Modifications to the Adopted Document

This recovery strategy replaces Environment Canada’s (2011) Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada which was posted as final on the Species at Risk Public Registry on August 11, 2011.

It also includes information on two additional yucca moth species, the Non-pollinating Yucca Moth (Tegeticula corruptrix) and the Five-spotted Bogus Yucca Moth (Prodoxus quinquepunctellus), species that are currently not listed in the Province of Alberta but are federally listed as Endangered.

Under SARA, there are specific requirements and processes set out regarding the protection of critical habitat. Therefore, statements in the provincial recovery plan referring to protection of critical habitat may not directly correspond to federal requirements. Recovery measures dealing with the protection of habitat are adopted; however, whether these measures will result in protection of critical habitat under SARA will be assessed following publication of the final federal recovery strategy.

The following sections have been included to address specific requirements of the federal Species at Risk Act (SARA) that are not addressed in the Alberta Soapweed and Yucca Moth Recovery Plan 2012-2022 (Part 2 of this document, referred to henceforth as “the provincial recovery plan”), to provide updated or additional information, and to include information on two additional yucca moth species, the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth.

Certain sections of the provincial recovery plan are not adopted and these are: 4.5 – Effective Protection of Critical Habitat; 8.0 – Action Plan; 9.0 – Timetable for Implementation and Schedule of Costs; and 10.0 – Socio-economic Considerations.

Recovery feasibility summary

Based on the following four criteria that Environment and Climate Change Canada uses to establish recovery feasibility, recovery of Soapweed, Yucca Moth, Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth has been deemed technically and biologically feasible.

1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.
Yes. Currently, there are two naturally occurring Footnote 2 Soapweed populations in Canada and the Yucca Moth, the Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth have been recorded reproducing at both sites. All three yucca moth species depend on the successful sexual reproduction (ie. fruit and seed production) of Soapweed and this is achieved only by the pollination of the Yucca Moth. Sexual reproduction in Soapweed has been confirmed at each naturally occurring Soapweed population, although it is not yet clear if the Yucca Moth population at the Pinhorn Grazing Reserve is viable given the low level of fruiting in 2011 (Hurlburt 2011), which would impact the viability of the other three species. Preliminary results from several management interventions indicate that the potential to increase Yucca Moth reproductive rates exists (Hurlburt 2011), which in turn could increase the recruitment of Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth. There are knowledge gaps concerning population size, structure, and dispersal abilities at each site.
2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
Yes. Suitable Soapweed habitat is presently available at the Pinhorn Grazing Reserve and Onefour Research Ranch (previously known as Onefour Research Substation) in Alberta. Since Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth only occur at Soapweed locations, the distribution of Soapweed limits these species’ distribution.
3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
Yes. The most significant threats to Soapweed, and thus to Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth recovery include wild ungulate herbivory, particularly at the Pinhorn location, lack of disturbance, cattle grazing, and oil and gas development (COSEWIC 2013a). Limiting factors such as the obligate mutualistic relationship between Soapweed and Yucca Moth, insect herbivory and extreme weather events also play significant role in the recovery of these species (COSEWIC 2013a). Some of these threats can be mitigated through beneficial management practices, protection of species and their habitat, and cooperation with stakeholders. Population monitoring and research into the biology and ecology of Soapweed and all three species of yucca moths can inform management actions.
4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.
Yes. The main recovery techniques will be the reduction of ungulate herbivory on Soapweed through erecting exclosures and Yucca Moth translocations at the Pinhorn site, and the conservation of suitable habitat at both locations. These techniques are thought to be effective for Soapweed and yucca moths, allowing for the achievement of the population and distribution objectives

1 COSEWICi species assessment information

For clarity, “Yucca Moth” (capitalized) refers to the pollinating Tegeticula yuccasella species, while “yucca moth” (lower case) refers to the three species or the family complex as a whole.

Date of assessment
May 2013
Common name (population):
Soapweed
Scientific name:
Yucca glauca
COSEWIC Status:
Threatened
Reason for designation:
This long-lived perennial is known from only three sites in southeastern Alberta and southwestern Saskatchewan, where it occurs mainly on south-facing coulee slopes. Plants are pollinated exclusively by Yucca Moth, which lays eggs in the flowers. In Canada, the species reproduces almost exclusively by vegetative spread. Seed production is limited by low numbers of Yucca Moth pollinators, while seedling establishment is negatively impacted by lack of natural disturbance, including fire suppression. Herbivory of flowering stalks by native ungulates also limits seed set. Despite improved management to limit the impact of threats, this perennial is designated Threatened. It is the only host for Yucca Moth, Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth, all of which were assessed as Endangered.
Canadian occurrence:
Alberta, Saskatchewan
COSEWIC status history:
Designated Special Concern in May 2002. Status re-examined and designated Threatened in May 2000 and May 2013.

i COSEWIC (Committee on the Status of Endangered Wildlife in Canada)

Date of assessment
May 2013
Common name (population):
Yucca Moth
Scientific name:
Tegeticula yuccasella
COSEWIC Status:
Endangered
Reason for designation:
Only two populations of the Yucca Moth are known from an extremely small and restricted area. This moth species has an obligate mutualistic relationship with Soapweed; Yucca Moth is the sole pollinator of Soapweed and its larvae depend on Soapweed seeds as a food source. One population may not be sustainable as it persists with human intervention that prevents severe herbivory of the flowers, fruits and stalks by wild ungulates. The Non-pollinating Yucca Moth larvae consume Soapweed seeds and compete with Yucca Moth for food. The loss of flowers or seeds as a result of ungulate herbivory is an ongoing threat, while in the long term Soapweed populations may be limited by the lack of fire and other disturbances that provide sites for the establishment of seedlings.
Canadian occurrence:
Alberta
COSEWIC status history:
Designated Endangered in April 2006. Status re-examined and confirmed in May 2013.
Date of assessment
May 2013
Common name (population):
Non-pollinating Yucca Moth
Scientific name:
Tegeticula corruptrix
COSEWIC Status:
Endangered
Reason for designation:
Only two populations of the Non-pollinating Yucca Moth are known from an extremely small and restricted area. One site has a small and fluctuating moth population, while only a single adult was observed from 1998-2011 at the other site. This moth species is an obligate seed parasite, the larvae feeding on Soapweed seeds. It relies on the mutualistic relationship between the Soapweed and its pollinator Yucca Moth, as fruit production is needed by larvae of the Non-pollinating Yucca Moth. The loss of flowers or seeds as a result of ungulate herbivory is an ongoing threat, while in the long term Soapweed populations may be limited by the lack of fire and other disturbances that provide sites for the establishment of seedlings.
Canadian occurrence:
Alberta
COSEWIC status history:
Designated Endangered in April 2006. Status re-examined and confirmed in May 2013.
Date of assessment
May 2013
Common name (population):
Five-spotted Bogus Yucca Moth
Scientific name:
Prodoxus quinquepunctellus
COSEWIC Status:
Endangered
Reason for designation:
The Five-spotted Bogus Yucca Moth is known from only two sites in Canada, one of which was discovered in 2011. This moth species is an obligate stem borer on the stalks of Soapweed. Larval survival is dependent on the mutualistic relationship between the Soapweed and its pollinator Yucca Moth.  The flowers on non-pollinated Soapweed stalks whither faster than pollinated stalks, resulting in almost complete mortality of immature life stages of Five-spotted Bogus Yucca Moth.  The loss of flowers or seeds as a result of ungulate herbivory is an ongoing threat, while in the long term Soapweed populations may be limited by the lack of fire and other disturbances that provide sites for the establishment of seedlings.
Canadian occurrence:
Alberta
COSEWIC status history:
Designated Endangered in April 2006. Status re-examined and confirmed in May 2013.

2 Species status information

Soapweed

Soapweed (Yucca glauca) has been listed as Threatened on Schedule 1 of Canada’s Species at Risk Act (SARA) since June 2003. The species is listed as Endangered under Alberta’s Wildlife Act but it has not been listed in Saskatchewan. The Saskatchewan Conservation Data Center (CDC) has recently ranked the single Saskatchewan Soapweed population as S1 (high extirpation risk; Saskatchewan Conservation Data Center 2015). This rank is based on the recent COSEWIC (2013b) assessment, which identified the population as self-sustaining (ie. it is reproducing), occupies similar habitat as the Alberta populations, and the location is within the conceivable natural range of this species (S. Vinge-Mazer pers. comm. 2016, see section 3.2 for further discussion).

The percentage of the global range in Canada for Soapweed is less than 1% (COSEWIC 2013b).

Soapweed is believed to be common throughout most of its North American range and is ranked as globally Secure (G5; NatureServe 2015). In the United States (US), the species is ranked as Secure (N5?; NatureServe 2015), but has not been assessed in most states (Table 1). In Canada and Alberta, Soapweed is ranked Critically Imperiled (N1 and S1 respectively; NatureServe 2015). All Soapweed plants in Saskatchewan are considered exotic thus a conservation status is not applicable at this time (SNA NatureServe 2015).

Yucca Moth Species

The Yucca Moth (Tegeticula yuccasella) has been listed as Endangered under SARA since 2005 while the Non-pollinating Yucca Moth (Tegeticula corruptrix) and the Five-spotted Bogus Yucca Moth (Prodoxus quinquepunctellus) have been listed as Endangered since 2007. The percentage of the global range in Canada for the three yucca moths is likely much less than 1%. All three yucca moth species are known to utilize several different species of the genus Yucca and as such have a much wider North American distribution than Soapweed (COSEWIC 2002, COSEWIC 2006 a,b).

In 2003, the Minister of Alberta’s Environment and Sustainable Resource Development (AESRD) approved the listing of Soapweed and Yucca Moth as Endangered under Alberta’s Wildlife Act based on recommendations from the Alberta Endangered Species Conservation Committee. Soapweed was listed as Endangered in November 2007; the Yucca Moth has not yet been listed. The Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth have not been assessed by the Alberta Endangered Species Conservation Committee and are not listed under Alberta’s Wildlife Act .

Throughout their global range the three yucca moths are common in Yucca spp. populations and are Apparently Secure/Secure globally (G4G5; Table 1; NatureServe 2015). In US, the conservation status of Yucca Moth is unranked (NNR) while Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth do not have a national or state conservation status rank (NatureServe 2015). In Canada and Alberta, the Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Yucca Moth are ranked Critically Imperiled (N1,S1; NatureServe 2015).

Table 1. NatureServea ranking for the Soapweed and three yucca moths species in North America (NatureServe 2015).
Species nameGlobal (G) RankNational (N) RankSubnational (S) Rank
SoapweedG5Canada (N1)Alberta (S1), Saskatchewan (SNA)
SoapweedG5United States (N5?)Arkansas (SNR), Colorado (SNR), Iowa (S3), Kansas (SNR), Missouri (S2), Montana (S4S5), Nebraska (SNR), New Mexico (SNR), North Dakota (SNR), Oklahoma (SNR), South Dakota (SNR), Texas (SNR), Wyoming (S4)
Yucca MothG4G5Canada (N1)Alberta (S1)
Yucca MothG4G5United States (NNR) 
Non-pollinating Yucca MothG4G5Canada (N1)Alberta (S1)
Five-spotted Bogus Yucca MothG4G5Canada (N1)Alberta (S1)

a The NatureServe conservation status ranks of a species is designated by a number from 1 to 5, preceded by a letter reflecting the appropriate geographic scale of the assessment (G = Global, N = National, and S = Subnational). The numbers have the following meaning: 1 = critically imperiled, 2 = imperiled, 3 = vulnerable, 4 = apparently secure, and 5 = secure. Also, NR =unranked, NA = not applicable and ? = inexact/uncertain.

3 Species information

3.1 Species description

Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth are small, nondescript, white or silvery, night-flying moths in the superfamily Incurvarioidea and family Prodoxidae, commonly known as the yucca moth family. Pellmyr (1999) examined the Tegeticula genus using morphological and molecular data and identified 12 species within the genus. In literature published prior to 2000 the term “T. yuccasella” is used to refer to all 12 species (see COSEWIC 2013a). Yucca Moth and Non-pollinating Yucca Moth are the only species of the Tegeticula genus found in Canada (COSEWIC 2013a). The Five-spotted Bogus Yucca Moth belongs to the genus Prodoxus. There are 10 species within the genus Prodoxus and the Five-spotted Bogus Yucca Moth is the only species of this genus found in Canada (COSEWIC 2013a). Members of the family Prodoxidae have only been found to be associated with plants of the genus Yucca and Agave (Davis 1967). In Canada, Soapweed is the single host plant species for all three yucca moths while Yucca Moth is the sole pollinator for Soapweed.

The obligate mutualistic Footnote 3 relationship between Soapweed and its pollinator the Yucca Moth is highly complex and thus cannot be described here in great detail (see Powell 1992, Dodd and Linhart 1994 for more information on these species’ ecology). A general description for Soapweed and the Yucca Moth is presented in the provincial recovery plan (Part 2: Species Biology). Very little is known about the biology and ecology of Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth in Canada. Most of what is known about the biology and ecology of the Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth comes from studies undertaken in the US.

Non-pollinating Yucca Moth

Non-pollinating Yucca Moth adults have a wingspan of 22.5 to 35 mm with slender white upper wings and brown undersides (COSEWIC 2006a). The species may be distinguished from the other yucca moth species by its relatively larger size and absence of small black dots on its wings (Pellmyr 1999). Females can be further distinguished by the complete absence of maxillary tentacles Footnote 4, which are a prominent feature in female Yucca Moths (COSEWIC 2006a).

In Alberta, the species is univoltine (only one generation per year) and adults emerge from the soil in early July through September, generally after pollination of Soapweed has occurred (COSEWIC 2006a). Adults gather at night, mate in Soapweed flowers, stalks or leaves, and die after only a couple of days (Kerley et al. 1993; Marr et al. 2000). Females insert their eggs (oviposition) in the early-stage Soapweed flowers and do not engage in pollination as Yucca Moths do (Csotonyi and Hurlburt 2000, Hurlburt 2007). The eggs of the genus Tegeticula are club-shaped, translucent and 2 mm in length (COSEWIC 2002) and hatch within 7-10 days (COSEWIC 2006a). The larva is less than 1 mm at hatching and reaches 14 mm at maturity (COSEWIC 2013a). Non-pollinating Yucca Moth larvae feed on a proportion of the developing Soapweed seeds and thus compete with Yucca Moth larvae for food. Developing larvae may consume up to 40% of seeds (COSEWIC 2013a). However, the reproductive success of the species is highly dependent on successful pollination by the Yucca Moth and the ability of Soapweed to produce fruit. Five to six weeks after hatching, larvae chew their way out of the fruit leaving a distinct hole in the pod and lower themselves to the ground via a silken thread. Larvae burrow 5-20 cm into the soil, spin a cocoon of silk and sand particles and enter prepupal diapause (Fuller 1990). The diapause period is at least one year but may be extended, with anecdotal evidence indicating up to three years (COSEWIC 2013a); mortality rates may be high during extended diapause (Fuller 1990).

Five-spotted Bogus Yucca Moth

Five-spotted Bogus Yucca Moth adults are the smallest of the three yucca moth species found in Canada with a wingspan of 11 to 21mm (Althoff et al. 2001, COSEWIC 2006b). The species can be differentiated from the other two yucca moths by its smaller size, lack of maxillary tentacles on females, and the presence of small black dots on the upper surface of the forewings (COSEWIC 2006b). The upper surface of the hindwings is light to medium gray (Althoff et al. 2001), always darker than the forewing and without the dark spots. The underside is medium brown with yellow where the wings overlap (Althoff et al. 2001). Both the forewings and hindwings have white wing fringes (Althoff et al. 2001). Males and females are identical in appearance, except females tend to be slightly larger than males (COSEWIC 2006b).

In Alberta the species is univoltine and adults fly for only a couple of days from early June to mid- July (COSEWIC 2006b). Adult Five-spotted Bogus Yucca Moths are often the earliest yucca moths to emerge but the flight period is similar to that of the Yucca Moth. Adults emerge from the Soapweed stalk about a week before Soapweed begins to flower and early in the season congregate on the leaves and then reside within Soapweed flowers as the season progresses. Adults mate within Soapweed flowers that open at night and females oviposit on the flowering stalk (Addicott et al. 1990, Pellmyr et al. 1996, James 1998). Females oviposit a single egg at a time 1-2 mm under the stalk surface (Davis 1967) and do not engage in pollination. A noticeable scar develops at each oviposition site which can be used to record species’ presence at a location. The eggs are variable in shape, but are usually soft, white and elongated with rounded ends (COSEWIC 2006b). Eggs hatch within about nine days and larvae burrow deeper into the flowering stalk and begin to feed on stem tissue. The larvae lack legs and early instars are whitish but turn pale green as they mature (COSEWIC 2006b). It is important to note that larvae only survive in flowering stalks that support viable fruit, thus the reproductive success of the species is highly dependent on the successful pollination of the Yucca Moth and the ability of Soapweed to produce fruit. Approximately 30 days after hatching, larvae spin a cocoon and enter a state of prepupal diapause within the stalk. In the spring, pupation occurs over approximately one week, and adults emerge through holes in the stalk created during the pupal stage (Davis 1967). Most adults emerge within a year; however extended diapause may occur (Powell 2001).

3.2 Species population and distribution

Global Population and Distribution

The global distribution of Soapweed extends from southeastern Alberta south to northern Texas and from the Rocky Mountains east to the Mississippi River (Figure 1: COSEWIC 2013b). One hypothesis suggests that the extreme northern and southern limits of the range may represent naturalized populations that have escaped from cultivated stock (Davis 1967).

Figure 1. Distribution of naturally occurring Soapweed, Yucca glauca, in North America (Hurlburt 2001).
Distribution of naturally occurring Soapweed, Yucca glauca, in North   America
Photo: © Hurlburt 2001
Long description for Figure 1

Figure 1 shows the distribution of Soapweed in North America. In Canada, the species is found in the southern tip of Alberta and southwestern Saskatchewan. It then descends south covering most of Montana and the western portion of North Dakota. The distribution continues towards the southeast covering most of Wyoming, Colorado, South Dakota, Nebraska, Kansas, Oklahoma, the northeastern tip of New Mexico and northern Texas.

The global distribution of Yucca Moth extends from southeastern Alberta south to the southern tip of Texas and from the Great Plains east to Michigan and Connecticut (COSEWIC 2002). Because  Yucca Moth utilizes several Yucca species as a host plant, its distribution is much greater than that of Soapweed (Figure 2; COSEWIC 2002).

Figure 2. Distribution of the Yucca Moth, Tegeticula yuccasella, in North America (COSEWIC 2013 a).
Distribution of the Yucca Moth, Tegeticula yuccasella, in North America
Photo: © COSEWIC 2013 a
Long description for Figure 2

Figure 2 shows the distribution of Yucca Moth. In Canada, only a small patch is found in southeastern Alberta, whereas its distribution covers approximately 80% of the mainland United States, from Montana in the northwest, New Mexico and Texas in the southwest, Pennsylvania in the northeast and Florida in the southeast.

The global distribution of Non-pollinating Yucca Moth extends from southeastern Alberta to northern Mexico and from California east to Nebraska (Figure 3; COSEWIC 2006a). Since the species has only been known since 1999 (Pellmyr 1999), the exact distribution in US is not considered complete (COSEWIC 2013a).

Figure 3. Distribution of the Non-pollinating Yucca Moth, Tegeticula corruptrix, in North America (COSEWIC 2013 a).
Distribution of the Non-pollinating Yucca Moth, Tegeticula corruptrix, in   North America
Photo: © COSEWIC 2013 a
Long description for Figure 3

Figure 3 shows the distribution of Non-pollinating Yucca Moth. In Canada, only a small patch is found in southeastern Alberta. It then descends south covering most of central Montana and continues straight into Wyoming, western South Dakota, western Nebraska, all of Colorado, western Kansas, all of New Mexico, a small portion of western Oklahoma, the western half of Texas, all of New Mexico, most of Arizona, and the southern tip of California.

Five-spotted Bogus Yucca Moth is widespread in North America. Its range extends from southeastern Alberta to northwestern Mexico and southern Texas, and from the Great Plains of US east to the Atlantic coast (Figure 4; COSEWIC 2006b). The species is the most geographically widespread species of the yucca moths, being associated with 15 Yucca spp.

Figure 4. Distribution of the Five-spotted Bogus Yucca Moth, Prodoxus quinquepunctellus, in North America (COSEWIC 2013a).
Distribution of the Non-pollinating Yucca Moth, Tegeticula corruptrix, in   North America
Photo: © COSEWIC 2013 a
Long description for Figure 4

Figure 4 shows the distribution of Five-spotted Bogus Yucca Moth. In Canada, only a small patch is found in southeastern Alberta, whereas its distribution covers approximately 85% of the mainland United States, from Montana in the northwest, Utah and Arizona in the west, Pennsylvania in the northeast and Florida in the southeast. The distribution also extends into Mexico, in northern Chihuahua and Coahuila.

Canadian Distribution

There are two naturally occurring Soapweed populations in Canada, and the Yucca Moth, the Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth have been reported from each location (COSEWIC 2013a, Hurlburt 2011). One Soapweed population is found at Onefour Research Ranch along the Lost River, Alberta, and the second population is found at Pinhorn Grazing Reserve near Manyberries, Alberta (Part 2: figure 1; Hurlburt 2001, Foreman et al. 2006). These populations are separated by approximately 15 km (AESRD 2013). The Soapweed and Yucca Moth populations at Onefour and Pinhorn sites are described in the provincial recovery plan (Part 2: Species Biology).

The closest native US Soapweed, and likely also the yucca moth, population, is located approximately 100 km south of the Onefour location; natural immigration of Soapweed plants from Montana is unlikely to occur (COSEWIC 2013b).

Throughout southern Saskatchewan and Alberta, numerous Soapweed plants also occur in horticultural settings, presumably originating as transplants from garden centres or from native populations. Evidence of fruit and seed production at several locations (e.g., Lethbridge valley, Medicine Hat, Magrath, Etzikom Museum) suggests that Yucca Moths are also present (Alberta Soapweed and Yucca Moth [ASYM] Recovery Team 2006, D. Johnson pers. comm. 2016), as the Yucca Moth is the sole pollinator of Soapweed (Marr et al. 2000). It is possible that some moths were transported as larvae or pupa within the soil when the Soapweed was transplanted to the new area (Hurlburt 2004); this would account for some short-term persistence of Yucca Moths at these locations as well as some limited reproduction and dispersal (D. Henderson pers. comm. 2008). In laboratory settings, a closely related yucca moth species, Prodoxus y-inversus, has been reported to remain in extended diapause in the soil for up to 30 years (Powell 2001).

Another explanation for the newly observed Soapweed fruit production is that the moths are dispersing from other occupied locations and expanding their range. No studies have examined yucca moth dispersal distance potential. In general, Prodoxidae moths live as adults for only a few days, are poor flyers, and thus have been assumed to be unable to travel great distances (Kerley et al. 1993, Marr et al. 2000, Hurlburt 2001). However, Dan Johnson at University of Lethbridge has examined Soapweed fruit production in horticultural settings for five years and concluded that Yucca Moth is capable of dispersal over miles, especially on wind fronts (D. Johnson pers. comm. 2016). Further research into Yucca Moth dispersal potential, persistence in horticultural settings, and the uncoupling of interactions among Soapweed and all three yucca moth species is required. Regardless of the fact that Soapweed plants in horticultural settings are sexually reproducing and the mode by which Yucca Moths are found in horticultural setting, this recovery strategy plan will not address Soapweed and yucca moth populations that occur in horticultural settings.

The recent Soapweed COSEWIC status report includes an introduced Soapweed population found at Rockglen, Saskatchewan, as part of the total Canadian population, which was considered in the overall species status assessment (COSEWIC 2013b). The addition of this third population is based on COSEWIC’s guidelines on manipulated populations (COSEWIC 2010), which indicate that individuals of a wildlife species can be included as part of the status assessment if they were accidently or intentionally introduced, they are self-sustaining, and occur in a natural setting within the natural range of the species. The Rockglen population was found in 2000 (D. Henderson pers. comm. 2008); visits and consultations with local landowners have indicated that this population was introduced from Montana 15-20 years ago by a relative of the family that once owned the land where the plants currently exist (T. Sample pers. comm. 2009).

Although an anecdotal observation of enlarged pedicels Footnote 5 was made in 2003 that might suggest that Yucca Moths are present at the location (ASYM Recovery Team 2006), the Rockglen population consist of only 6 Soapweed clones Footnote 6 and does not contain a self-sustaining Yucca Moth population (COSEWIC 2013b). Sexual reproduction, which introduces variation within a population, is crucial for the long term survival of plants, especially in a changing environment. Lack of sexual reproduction within Soapweed populations may impact the long-term survival of the species and as such factors that impact sexual reproduction should be considered (COSEWIC 2013a). Thus, in the absence of a self-sustaining Yucca Moth population that would allow for sexual reproduction, the Soapweed population at the Rockglen location is only reproducing vegetatively and thus it is not considered self-sustaining at this time. Furthermore, based on the COSEWIC guidelines, status assessments must clearly identify if the introduced population is part of the wildlife species (ie. Designable Unit) being considered for assessment. Thus, until genetic studies indicate that the Soapweed population at the Rockglen location is genetically similar to the native populations found in Alberta, this population is considered by Environment and Climate Change Canada (ECCC) as being introduced, not self-sustaining, and thus not part of the total Canadian population.

Several Five-spotted Bogus Yucca Moths have been collected in southern Ontario in the 1930s and 1950s and these are believed to have originated from cultivated Soapweed plants (COSEWIC 2013a). Currently, there are no positive records of Non-pollinating Yucca Moth or the Five-spotted Bogus Yucca Moth using Soapweed in horticultural settings in Alberta although several yucca moth larvae have observed at a few locations (COSEWIC 2013a, D. Johnson pers. comm. 2016). The presence of these yucca moths in horticultural settings cannot be ruled out since only live adults or DNA analysis from larval tissues would prove that these two species do occur in horticultural settings (D. Johnson pers. comm. 2016).

As more information becomes available, the status of Soapweed and its three associated yucca moths in horticultural settings and at the Rockglen location will be reassessed by ECCC as needed.

Soapweed Canadian Population

Population data on Soapweed (Table 2) has been collected since 1976 using various sampling methods, indices, search efforts, and timing periods (see COSEWIC 2013a for descriptions); as such, the results of these studies cannot be effectively compared to estimate an accurate Canadian population size at this time.

Table 2. Summary of Soapweed population surveys conducted at Pinhorn Grazing Reserve and Onefour Research Ranch, Albertab.

Year
Pinhorn
Clonesc
Pinhorn
Rosettesd
Pinhorn
% Fruit in rosettes
Onefour
Clones
Onefour
Rosettes
Onefour
% Fruit in rosettes
Reference
1976450-->55,000--Milner 1977
1998423e1,38308,49928,1740.001Csotonyi and Hurlburt 2000
20041,3663,5100.001---Foreman et al. 2006
2006f---45,560-71,540153,980-246,69021Bradley et al. 2006
2011--10.08--0.004Hurlburt 2011

b This is the best information available to Environment and Climate Change Canada (up to August 2016)

c A clone refers to a group of plants, or rosettes, originating by vegetative propagation from a single parent.

d A rosette (also referred to as a ramet) indicates the circular arrangement of leaves that make up a single plant that produces a single inflorescence.

e This number represents an addition of 19 clones which were found during the 2004 surveys and represents the actual population estimate for that location (COSEWIC 2013a).

f Increased number of the 2006 survey from the 1998 survey is attributed to the different survey method used (ie. methods used to identify clones) and the time of year of the study rather than an increase in population size. Estimates from the 1976 and 2006 are roughly comparable

Yucca Moths Canadian Population

Population surveys for Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moths are limited and these have been carried out at various times of the year and using various techniques and indices that cannot be currently compared to estimate population size or trends (COSEWIC 2013a). For example, oviposition scars in the carpel walls of the Soapweed fruit has been used as an index to determine Non-pollinating Yucca Moth seasonal activity (see COSEWIC 2006 for vital rate), however this is not a direct estimate of abundance. Recruitment of new moths (ie. larvae per fruit) has been also used as an additional index, but this requires fruit dissection which is destructive to the Soapweed plant, as well as Yucca Moth and Non-pollinating Yucca Moth larvae that might be present in the fruit (COSEWIC 2006). At the Pinhorn location students from Medicine Hat College Environmental Reclamation program, in partnership with volunteers from the Alberta Native Plant Council, have surveyed portions of the Soapweed population from 2009 to 2015, but these visits occur in fall when yucca moth adults are no longer present in the area (C. Linowski pers. comm. 2016). Although data on the number of moth emergence holes per fruit has been collected at this site, this index cannot be used to clearly separate the density of Yucca Moths vs. Non-pollinating Yucca Moth since the larvae of both species develop in the fruit and the exit holes cannot be differentiated.

Onefour Research Ranch

Non-pollinating Yucca Moth at the Onefour site has been surveyed between 1998 and 2007 by examining Soapweed fruit. The number of oviposition scars per fruit has varied substantially annually, ranging from a low of 0.071 in 2007 to a high of 13.939 ± 0.875 (mean ± SE) in 2002 (Hurlburt 2007). Larvae per fruit ranged from 3.636 ± 0.254 in 2002 to 0.033 ± 0.033 in 2003. These values are comparable to those found in the closest Montana population (see COSEWIC 2013a for vital rates).

The number of Five-spotted Bogus Yucca Moths adults present in flowers at the Onefour site was counted in 2002, 2007 and 2011 (COSEWIC 2013a). Density per flower was 0.310 ± 0.023 in 2002, 1.086 in 2007 and 0.500 in 2011 (only 6 flowers examined in 2011). In 2003, the number of ovipositions per inflorescence (flowering stalk) and the number of larvae per inflorescence was determined for 16 clones. There were 652.9 ± 130.4 ovipositions per stalk and 27.4 ± 8.2 larvae per stalk. These values were comparable to those observed in Montana (COSEWIC 2013a).

Pinhorn

At the Pinhorn site, Soapweed fruit production had not been observed since 1997, thus the Yucca Moth population was considered extremely low or possibly extirpated (COSEWIC 2002). In the absence of Soapweed sexual reproduction, viable populations of all three yucca moths could not persist. In 2004, a comprehensive inventory of the Soapweed population was conducted and evidence of Yucca Moth reproduction was observed (Foreman et al. 2006). In 2007, effective habitat management interventions, by means of fencing off three sections of the Soapweed population to reduce wild ungulate (ie. Pronghorn [Antilocapra Americana] and Mule Deer [Odocoileus hemionus]) herbivory, resulted in approximately 10 Soapweed plants producing fruit the following year (J. Nicholson pers. comm. 2009) indicating that the Yucca Moths were still present and reproducing at the site. In 2008, a single Soapweed stalk containing 14 unripe fruit was collected from the Etzikom Windmill Museum garden and translocated to the Pinhorn location (AESRD 2013). Surveys conducted in 2011 indicated that 70 Soapweed plants found within the exclosures produced fruit (40.63 % of clones and 10.08 % of the rosettes); only one additional fruit was located outside the exclosures (Hurlburt 2011). Although these recent fruit production observations indicate that the Yucca Moth population is slowly recovering at the Pinhorn location, it is not yet clear if these reproductive rates indicate a viable Yucca Moth population (D. Hurlburt pers. comm. 2009, AESRD 2013).

Much less is known about the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth populations at Pinhorn. In August 1998 a single live adult Non-pollinating Yucca Moth was captured in flight (Csotonyi and Hurlburt 2000), and in 2000, several cocoons with larvae in prepupal diapause were sifted from the soil (COSEWIC 2013a). No adults were observed in 2011, however the survey was conducted during a time when direct observations were unlikely (Hurlburt 2011). Although there have been no observations of the Non-pollinating Yucca Moth at Pinhorn since 2000, it does not indicate that the species is not present at the location. Timing of the survey is one reason for lack of observations, as visits to the location generally occur in late September or early October when Soapweed plants have set fruit and live adults are no longer present (C. Linowski pers. comm. 2016).

The Five-spotted Bogus Yucca Moth was first confirmed from the Pinhorn location in August 2011 by examining oviposition scars on flower stalks from Soapweed plants located within exclosures (Hurlburt 2011, COSEWIC 2013a). No adults were observed, however surveys were conducted during a time when direct observations were unlikely (Hurlburt 2011). Although the oviposition rate (50.78%) was significantly lower than that recorded at the Onefour location (>92 %), this observation illustrates that the species is present, and if Soapweed plants are protected from herbivory, the species can reproduce successfully. Five-spotted Bogus Yucca Moth population at Pinhorn is still considered low due to the lack of fruit production (and inflorescences in which to lay eggs) as a result of herbivory for many generations (COSEWIC 2013a) and is unknown if these reproductive rates indicate a viable Five-spotted Bogus Yucca Moth population.

Soapweed and Yucca Moths Trends

It was believed that since the first systematic population survey completed in 1976 the Soapweed population, and thus its associated yucca moths, at the Onefour Research Ranch has expanded from the coulee slopes onto the upland prairie (Hurlburt 2001). However, further investigation indicated that there is no evidence of new Soapweed seedlings within the upland prairie and a recent flowering event between 1999-2003 places the plants at about of age 20-25 years, the age when flowering first occurs (Hurlburt 2007, COSEWIC 2013b). It is speculated that a prairie fire that occurred in the area in the late 1970s might have created favourable seed germination conditions for seedling establishment (Hurlburt 2007).

The Pinhorn Soapweed population is spreading both vegetatively and sexually on the west facing coulee slopes especially in eroded areas where seedlings can become established (C. Linowski pers. comm. 2016). Furthermore, within the exclosures a steady positive trend in fruit production and moth emergence holes has been recorded (Hurlburt 2011, C. Linowski pers. comm. 2016).

3.3 Needs of Soapweed and the Three Yucca Moths

Soapweed, and thus the three associated yucca moth species, inhabit a variety of habitats throughout their North American range. The habitat needs of Soapweed and Yucca Moth are discussed in the provincial recovery plan (Part 2: Habitat Requirements). Habitat needs of the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth are less well known but assumed to be similar to that of the Yucca Moth with a few exceptions.

A crucial element in the survival of both the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth is the survival and sexual reproduction of its host plant, Soapweed. The Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth have an obligate parasitic relationship with Soapweed. Soapweed provides oviposition sites for adults of all yucca moth species, seeds as food for developing Non-pollinating Yucca Moth larvae, inflorescence stem tissue as food for developing Five-spotted Bogus Yucca Moth larvae, and inflorescence stems as shelter during prepupal diapause for the Five-spotted Bogus Yucca Moth.

Soapweed with fruit are often inhabited by aphids, which are tended by several species of ants. While ants can inflict damage on Soapweed by chewing on Soapweed buds, ants are less likely to damage Soapweed when aphids are present (Perry 2001, Perry et al. 2004; Snell and Addicott 2008b). In Alberta, Soapweed inhabited by ants experienced a 60% increase in the number of viable seeds produced per fruit, because ants reduced ovipositing by Non-pollinating Yucca Moths (Snell and Addicott 2008b). Therefore, the presence of ants can decrease Non-Pollinating Yucca Moths, but may increase the number of Yucca Moths as they will have less competition for food.

The survival of Five-spotted Bogus Yucca Moth larvae is dependent upon the presence of Yucca Moth to pollinate Soapweed flowers in order to successfully reproduce and produce fruit. The species may also benefit from the presence of aphids feeding on the sap associated with the stalk. Five-spotted Bogus Yucca Moth larvae only survive while the Soapweed stalk is green, although their eggs may be spread throughout the stem. Soapweed stalks, however, only remain ‘green’ up to the highest position of fruit along the stalk, unless aphids are present which allows the stalks to remain green for longer (Snell and Addicott 2008a). Aphids may therefore enhance the survival of Five-spotted Bogus Yucca Moth larvae. The flowers on non-pollinated Soapweed stalks wither faster than pollinated stalks, resulting in almost complete mortality of immature life stages of Five-spotted Bogus Yucca Moth (COSEWIC 2013a).

4 Threats

4.1 Description of threats

Threats to Soapweed and the Yucca Moth are discussed in the provincial recovery plan (Part 2: Threats and Limiting Factors) and these are believed to be similar to those faced by the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth with a few clarifications. Horticultural and medicinal uses (Threat 3.2) and off-road vehicle use (Threat 3.3) were identified in the provincial recovery plan as threats, particularly at the Onefour location; however these threats have been mitigated and have not been a concern for more than 10 years, thus they are currently not considered a threat to these species (COSEWIC 2013 a,b).

In addition to the threats listed in the provincial recovery plan, lack of disturbance has been identified as a threat to Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth populations in Canada (COSEWIC 2013a,b). Natural disturbances, such as climatic, pyric (fire), and biotic disturbances, have played an important role in the maintenance, diversity, and productivity of North America’s mixed-grass prairie ecosystem. These disturbances maintain open habitat and prevent establishment of competitive grasses or woody vegetation. In Alberta, Soapweed is associated with sandy loam soils, protected and sparsely vegetated south-facing coulee slopes that are influenced by some level of disturbance (COSEWIC 2013 a). The level of tolerance of Soapweed to fire in terms of frequency, intensity, and timing is unknown however laboratory trials indicate that Soapweed seeds are not fire-dependent, and high heat intensity for only 5 minutes can reduce germination (Keeley and Meyers 1985). Since Soapweed seedlings are poor competitors, it is possible that fire plays an important role in creating suitable habitat rather than stimulating germination (COSEWIC 2013b).

Furthermore, the continual survival and recovery of the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth strongly depends on the survival, abundance, and continual pollination of the Soapweed by the Yucca Moth. This is because the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth have an obligate relationship with Soapweed such that neither species can reproduce without sexual reproduction in Soapweed. This dependency is exacerbated by the fact that Soapweed and Yucca Moth populations in Canada are small, have a small area of occupancy, and are isolated.

At Pinhorn, high wild ungulate herbivory rates and reproductive failure of Soapweed continue to occur outside the enclosed fenced areas (Hurlburt 2011) and this remains a key threat at this location (AESRD2013). In addition, invasion by Japanese Brome (Bromus arvensis) and Downy Brome (Bromus tectorum) which are spreading from oil and gas access roads has been identified as an additional potential future threat at this location (C. Linowski pers. comm. 2016).

5 Population and distribution objectives

The provincial recovery plan contains the following recovery goal for Soapweed and Yucca Moth (Part 2: Recovery Goal):

  • The long-term goal of the recovery plan is to maintain the existing habitat and distribution of Soapweed and Yucca Moths in Alberta and to enhance the Yucca Moth population at the Pinhorn site. This will require the maintenance of naturally, self-sustaining populations of Soapweed and Yucca Moth at the Onefour site and an increase in the reproductive capacity at the Pinhorn site.

Under SARA, population and distribution objectives must be established for endangered or threatened species. Consistent with the recovery goal set out in the provincial recovery plan, Environment and Climate Change Canada establishes the following short and long term population and distribution objectives for Soapweed and Yucca Moth, and also includes the addition of two species, the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth:

  • In the short term (5 years): at the Pinhorn location increase Soapweed and Yucca Moth reproductive capacity Footnote 7; and
  • In the long term (>10 years): maintain the current distribution of all four species at the two naturally occurring locations , Pinhorn and Onefour, as well as at any additional naturally occurring populations discovered in the future.

At this time, it is not feasible to establish more quantitative population objectives for any of the four species. Soapweed population size estimates over the years have been inconsistent due to survey techniques, making it difficult to apply differences in size estimates to actual changes in population abundance. Very few population surveys have been completed for the three yucca moths, and these estimates cannot be compared at this time. In Canada, all four species exist at the northern fringe of their global range, and likely have always been limited by the restricted availability of suitable habitat and climate. Thus, it can be concluded that a species that was never historically widespread in Canada is unlikely to become widespread in the future and will probably always have a limited distribution and area of occupancy in Canada.

Regarding the Rockglen Soapweed population, unless genetic studies indicate that this population is genetically similar to the native populations found in Alberta, this population is considered by ECCC as being introduced, not self-sustaining, and thus not necessary for achieving the survival and recovery of the Canadian Soapweed population.

6 Broad strategies and general approaches to meet objectives

6.1 Actions already completed or currently underway

The provincial recovery plan outlines actions already completed or currently underway for Soapweed and the Yucca Moth (Part 2: Recent Recovery and Conservation Efforts). Additional actions completed or underway for the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth include:

  • Soapweed plants at the Onefour site were monitored to estimate Non-pollinating Yucca Moth abundance from 1999 to 2003 (Hurlburt 2004).
  • In 2002 - 2003, Soapweed plants at the Onefour site were monitored for the presence of Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth (Snell 2004; Snell and Addicott 2008 a,b).
  • Yucca Moth, Non-pollinating Yucca Moths and Five-spotted Bogus Yucca moths were counted at the Onefour site during a week-long visit in 2007 (Hurlburt 2007).
  • An inventory of the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth population was undertaken at the Pinhorn site in 2004 to determine the size of the population and level of larval emergence (Foreman et al. 2006);
  • Completion of an inventory of the Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth populations at the Onefour and Pinhorn sites by an independent biological consultant in 2011 for the updated COSEWIC status report for both species (see Hurlburt 2011, COSEWIC 2013a).
  • Additional exclosures at the Pinhorn site to protect Soapweed plants form wild ungulate herbivory will be installed in spring 2017 (S. Robertson pers. comm. 2016).

6.2 Narrative to support the recovery planning table

The provincial recovery plan identifies recovery strategies for Soapweed and Yucca Moth (Part 2: Recovery Strategies). These strategies are also appropriate and sufficient to support recovery of the Non-pollinating Yucca Moth and the Five-spotted Bogus Yucca Moth in Canada, due to their obligate relationship with Soapweed in Canada, and as such are adopted as ECCC broad strategies.

7 Critical habitat

This section replaces section 4: “Critical Habitat” in the provincial recovery plan.

Section 41(1)(c) of SARA requires that recovery strategies include an identification of the species’ critical habitat, to the extent possible, as well as examples of activities that are likely to result in its destruction. Under section 2(1) of SARA, critical habitat is “the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in the recovery strategy or in an action plan for the species”.

Yucca Moth, the Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth have an obligate relationship with the host plant, Soapweed, and the moths do not occur outside the distribution of Soapweed. Given this, the critical habitat for the three yucca moth species is considered the same as the critical habitat identified for Soapweed.

Critical habitat for Soapweed and Yucca Moth was first described in Alberta’s 2006 Soapweed and Yucca Moth Recovery Plan (ASYMRT 2006) and re-adopted in the updated 2013 provincial recovery plan (Part 2: Critical Habitat). Critical habitat was identified as the area occupied by the two known naturally occurring Soapweed populations as of 2006 boundaries. The total area identified in the provincial recovery plan consisted of 1.8 km2 (182 ha) at Onefour and 0.02 km2 (2.65 ha) at Pinhorn (Part 2: Figure 2 and Figure 3). However, since several plants on the upland were undocumented during the 2006 survey this critical habitat identification was considered incomplete and necessitated revision (Hurlburt 2007).

7.1 Identification of the species’ critical habitat

Critical habitat is fully identified in this recovery strategy and encompasses all naturally occurring Soapweed populations Footnote 8 known to exist in Canada. Critical habitat is identified at two locations (Onefour Research Ranch and Pinhorn Grazing Reserve) and is considered sufficient to achieve the population and distributions objectives at this time. Data collected during field surveys conducted in 2004, 2006, and 2007, and occurrence Footnote 9 information obtained from Alberta Environment and Parks and Alberta Conservation Information Management System were used to identify critical habitat (Foreman et al. 2006, Bradley et al. 2006, D. Hurlburt unpubl. data).

Critical habitat identification is amended in this recovery strategy for two reasons. First, since 2006 when Soapweed and Yucca Moth critical habitat was first described in the Alberta provincial recovery plan, several Soapweed plants have been found outside the boundaries designated as critical habitat at the Onefour location (Hurlburt 2007). These mature plants, which were missed during the original inventory rather than being new recruits (Hurlburt 2007) were not included in the updated provincial recovery plan (Part 2: Critical Habitat). Secondly, the approach used to identify Soapweed critical habitat was inconsistent with the approach used for the identification of other prairie plant species at risk (e.g., Tiny Cryptantha Cryptantha minima, Small-flowered Sand-verbena Tripterocalyx micranthus). As such, identification of critical habitat for Soapweed is based on best available information and follows the decision tree developed by the Recovery Team for Plants at Risk in the Prairie Provinces as guidance for identifying critical habitat for all terrestrial and aquatic prairie plant species at risk (Appendix A). This approach fulfills the reproductive, dispersal, range expansion, and long-term persistence requirements of the Soapweed and yucca moth populations in Canada.

The decision tree first requires consideration of the quality of available information on Soapweed occurrences in Canada, with the choice of accepting or rejecting any given occurrence for consideration as critical habitat based on three criteria that were used to define the quality of information (Appendix A). The three criteria relate to the number of years since the last known occurrence was relocated and/or revisited, the precision and accuracy of the geographic referencing systems used to locate the occurrence and an evaluation of whether the habitat, in its current condition, remains capable of supporting the species. If the result of this first decision is that a given occurrence is not accepted for consideration, then the location of the postulated occurrence is excluded from consideration as critical habitat at this time. However, it may be considered in future identification of critical habitat, depending on the outcome of future surveys.

The second decision is based on how well the habitat requirements of the plant are defined. Soapweed habitat is restricted to coulees and semi-arid grasslands on coarse-textured soils. These areas are influenced by some level of disturbance and are poorly defined in space. Thus, identification of critical habitat for Soapweed is occurrence-based rather than habitat-based (Appendix A). Based on Criteria 2a (Appendix A), critical habitat is identified as the Soapweed occurrence and an addition of 300 m as a critical function zone extending from each plant occurrence..

Although the exact extent of habitat required by Soapweed to fulfill the reproductive, dispersal, and long-term survival needs is not fully known, the 300 m critical function zone is based upon a detailed literature review that examined edge-effects of various land use activities that could affect resource availability and contribute to negative population growth for native prairie plants (Environment Canada 2012, Appendix D). Thus, to ensure the long-term persistence, and where feasible, the natural expansion of Soapweed in Alberta, the 300 m critical function zone is thought to be the minimum distance needed to maintain the habitat required to meet the population and distribution objectives. As new information on species’ habitat requirements and site-specific characteristics become available, this distance may be refined.

In this recovery strategy, critical habitat is fully identified for the two naturally occurring Soapweed populations in Alberta and the three associated yucca moth species; the Yucca Moth, the Non-pollinating Yucca Moth, and the Five-spotted Bogus Yucca Moth. Critical habitat was identified to include all of the area where Soapweed occurs plus a 300 m critical functional zone around each occurrence. Critical habitat totals 4.12 km2 (412 ha) and is found within Pinhorn Grazing Reserve (0.56 km2) and Onefour Research Ranch (3.56 km2)(Figure 5; Appendix C).

Occurrence data for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth is considered sensitive due to the potential risks of human disturbance and collection of Soapweed for horticultural and medicinal uses (Part 2 Threats and Limiting Factors). Critical habitat identified for the these four species is therefore presented using 10 X 10 km UTM grid squares to indicate the general geographic areas containing the actual critical habitat polygons in order to minimize risks to these species. More detailed information, such as a critical habitat map, may be requested by contacting Environment and Climate Change Canada – Canadian Wildlife Service at ec.planificationduretablissement-recoveryplanning.ec@canada.ca.

Figure 5. Critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five spotted Bogus Yucca Moth occurs within the 10 km x 10 km UTM grid squares (red outline) where the criteria set out in Section 7.1 are met while the US landbase (shaded grey) is excluded. This standardized national grid system indicates the general geographic area containing critical habitat and detailed critical habitat polygons are not shown. Based on the identification criteria, the grid squares indicated contain approximately 4.12 km2 (412 ha) of critical habitat.
Critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth
Long description for Figure 5

Figure 5 shows the two grid squares where these species are found in Alberta. The first covers the southeastern half of Pinhorn Provincial Grazing Reserve. The second grid square falls mainly in the United States with the Canadian portion covering the eastern half of Onefour Heritage Rangeland.

Biophysical Attributes of Critical Habitat

Biophysical attributes of critical habitat include, but are not limited to, soils and bedrock geology, surface and sub-surface hydrology, vegetation and vegetation community composition, and landforms that occur within the two polygons (Table 3). Rivers, lakes, wetlands and forests are exempt from this definition and are therefore not considered critical habitat. Existing human infrastructure such as buildings, roads and trails, fences, and dugouts within the area identified as critical habitat do not possess the biophysical attributes of critical habitat and are therefore not included in the critical habitat identification.

Within the areas identified as critical habitat, one or more biophysical attributes may occur at a site (Table 3).

Table 3. Summary of critical habitat and biophysical attributes for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth in Alberta.
Critical HabitatDetails
LocationsAlberta: 1) Pinhorn Grazing Reserve; 2) Onefour Research Ranch where Soapweed plants occur plus a 300 m critical functional zone around each plant
MapFigure 5 (detailed critical habitat polygon maps may be obtained from ECCC upon request)
Biophysical Attributes for Soapweed (one or a combination of)
  • sparsely-vegetated south- or east-facing coulee slopes [slope rage from 34° (northeast) to 220° (south-southwest)];
  • sparsely-vegetated semi-arid native grassland
  • coarse-textured soils, alkaline and regosolic (undeveloped) without a shallow hardpan
Biophysical Attributes for Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth
  • occurrence of native Soapweed plants
Exceptions
  • rivers, lakes, wetlands and forests
  • existing human infrastructures such as buildings, roads and trails, fences, and dugouts

7.2 Activities likely to result in the destruction of critical habitat

Destruction is determined on a case by case basis. Destruction would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species. Destruction may result from a single or multiple activities at one point in time or from the cumulative effects of one or more activities over time. Activities described in Table 4 outline examples of activities likely to cause destruction of critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth; however, destructive activities are not limited to those listed.

Some activities that result in a temporary alteration of critical habitat (e.g., fires) may have the potential to contribute to the future quality of critical habitat, given proper management. Some disturbance to Soapweed habitat may be beneficial to the species by maintaining open habitat and managing invasive species or woody vegetation growth within a given site. Activities required to manage, inspect, and maintain existing infrastructures that are not critical habitat but whose footprints may be within or adjacent to critical habitat units are not examples of activities likely to result in the destruction of critical habitat provided that they are carried out in a manner consistent with critical habitat conservation. The impact of management activities on critical habitat may be lessened or avoided if activities take place when yucca moths are not active such as prior to flowering or after seed production. More detailed information on the specific activities likely to destroy critical habitat may be requested by contacting Environment and Climate Change Canada – Canadian Wildlife Service at ec.planificationduretablissement-recoveryplanning.ec@canada.ca.

Table 4. Activities likely to result in the destruction of critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth.
Description of activityDescription of effect (on biophysical attribute or other) in relation to function loss of critical habitatAdditional information
Conversion of native prairie to cropland or non-native grasslandActivity would result in the direct loss of critical habitat by removing or disturbing the substrate within which Soapweed grows, and altering soil biophysical conditions (e.g. structure, porosity, temperature, moisture) required for germination, establishment, and growth. This activity leads to vegetation community changes such that the area becomes dominated by crops, non-native plants, and invasive species.This activity must occur within the bounds of critical habitat to cause destruction, may result in destruction either directly or cumulatively, and is applicable at all times of the year.
Covering of soils, which can be caused by activities such as construction of infrastructure, including oil and gas wells, pipelines, buildings, and roads.Activity would result in the direct loss of critical habitat by removing or disturbing the substrate within which the Soapweed grows, and altering soil biophysical conditions (e.g. structure, porosity, temperature, moisture) required for germination, establishment, and growth. These activities result in increased foot and road traffic by humans which could also lead to vegetation community changes such that the area becomes dominated by non-native plants and invasive species.This activity must occur within the bounds of critical habitat to cause destruction, may result in destruction either directly or cumulatively, and is applicable at all times of the year.
Off-road vehiclesSoapweed plants may be damaged through direct crushing by vehicles. Continuous traffic may increase potential for soil compaction and erosion. Plant build-up under vehicles or within tires can be source of non-native or invasive alien plant species; once established, invasive species can alter hydrology, soil nutrient and moisture availability, and create shade, resulting in direct competition with Soapweed, such that population declines occur, effectively destroying the critical habitat.This activity must occur within the bounds of critical habitat to cause destruction, may result in destruction either directly or cumulatively, and is applicable at all times of the year.
Prolonged cattle over-grazing (high intensity and/or duration during Soapweed flowering and seed development)If activity was undertaken during Soapweed flowering and seed development, it would result in the direct consumption or trampling of Soapweed inflorescence, which are the single larval host plant for the three yucca moths. Activity could result in the direct consumption of Yucca Moth, which is the single pollinator of Soapweed.This activity must occur within the bounds of critical habitat to cause destruction, may result in destruction either directly or cumulatively, and is applicable at all times of the year.
Indiscriminate application of fertilizers or pesticides, which can be caused by activities such as: non-selective spraying of broad-leaf herbicide and insecticide, or arbitrary additions of fertilizers to soilHerbicide and fertilizer can alter soil or water nutrient status, creating conditions suitable for some plant species and unsuitable for others, such that species composition in the surrounding plant community can change. Changes to soil or water nutrient status will also influence the outcome of interspecific competition for nutrients. Pesticide runoff and drift can alter plant and pollinator communities, thereby possibly reducing the capability of the habitat to support Soapweed.This activity may result in destruction of critical habitat whether it occurs within or outside the bounds of critical habitat (e.g. chemical drift, groundwater or overland flow of contaminated water), may result in destruction either directly or cumulatively, and is applicable at all times of the year.
Spreading of wastes or release of deleterious materials, which can be caused by activities such as: spreading or release of materials such as manure and septic fluidsThese substances have the potential to change soil nutrient status and availability of these nutrients for uptake by plants; species composition; and increase surrounding competitor plants, effectively destroying the critical habitat. These liquid or semi-liquid materials can infiltrate the surface in the short-term, but leave little long-term evidence at the surface that could point to the cause of negative changes observed thereafter.This activity may result in destruction of critical habitat whether it occurs within or outside the bounds of critical habitat (e.g. drift, groundwater or overland flow of contaminants), can be a direct or cumulative effect, and is applicable at all times of the year.
Introduction or promotion of invasive species, which can be caused by activities such as, but not limited to: intentional dumping or spreading of feed bales containing viable seed of invasive non-native species; seeding invasive species within critical habitat; transporting invasive species (e.g., on wheel tires); or planting of woody vegetation (shrubs and trees).Once established, invasive plant species and woody vegetation can alter hydrology, soil nutrient and moisture availability, and create shade, resulting in direct competition with Soapweed, such that population declines occur, effectively destroying the critical habitat. Critical habitat may be destroyed by invasive alien species as well as by other noxious prohibited weeds and aggressive opportunistic species. It may also be destroyed by the following species which are not restricted by any legislation due to their economic value: Smooth or Awnless Brome Bromus inermis), Kentucky Bluegrass (Poa pratensis), Crested Wheatgrass (Agropyron cristatum), Yellow Sweet Clover (Melilotus officinalis), White Sweet Clover (Melilotus alba).This activity can occur within or adjacent to the bounds of critical habitat to cause its destruction, can be a direct or a cumulative effect, and is applicable at all times of the year.
Alteration to hydrological regimes, which can be caused by activities such as: temporary or permanent inundation from construction of impoundments downslope or downstream; releases of water upslope and upstream, including but not limited to damming, ditching, drainage, culvert installation, road widening or straightening; or residential/cottage developments that affect the hydrology of critical habitatAs the seed bank and plants of Soapweed are adapted to well-drained soils, flooding or inundation by substances like water, even for a short period of time, can be sufficient to alter habitat enough to be unsuitable for survival and re-establishment. Altering hydrology can also result in too dry conditions, mimicking drought. For example, road construction can interrupt or alter overland water flow, altering habitat conditions and threatening the long-term survival of the species at a particular location. An increase in moisture may also lead to increased encroachment by woody vegetation and some invasive plant species.This activity may result in destruction of critical habitat whether it occurs within or outside the bounds of critical habitat, may result in destruction either directly or cumulatively, and is applicable at all times of the year

8 Measuring progress

The performance indicators presented below provide a way to define and measure progress toward achieving the population and distribution objectives.

  • In the short term (5 years): the reproductive capacity of Soapweed and Yucca Moth at the Pinhorn location has increased; and
  • In the long term (>10 years): distribution of all four species has been maintained at the two naturally occurring populations (Onefour and Pinhorn), and at any additional natural occurring populations discovered in the future.

9 Statement on action plans

One or more action plans for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca will be completed by 2021. It is important to note that these four species form a web of highly interdependent, specialized organisms. Because of these complex food web interactions, it is recommended that a multi-species action plan be developed for Soapweed and its associated yucca moths. Recovery actions for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth may be adopted from the recovery actions described in the provincial recovery plan (Part 2: Action Plan). Coordination with other recovery teams should be considered when developing multi-species action plans at the landscape or ecosystem level and when managing large tracts of land. Other species at risk found within Soapweed and Yucca Moth habitat are listed in Appendix B.

10 References

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Alberta Environment and Sustainable Resource Development. 2013. Alberta Soapweed and Yucca Moth Recovery Plan, 2012-2022. Alberta Environment and Sustainable Resource Development, Alberta Species at Risk Recovery Plan No. 25. Edmonton, AB. 24 pp.

Alberta Soapweed and Yucca Moth Recovery Team. 2006. Recovery plan for soapweed and yucca moth in Alberta 2006-2011. Alberta Sustainable Resource Development, Fish and Wildlife Division, Alberta Species at Risk Report No. 11. Edmonton, Alberta. 21 pp.

Althoff, D.M., J.D. Groman, K.A. Segraves, and O. Pellmyr. 2001. Phylogeographic structure in the bogus yucca moth Prodoxus quinquepunctellus (Prodoxidae): comparisons with coexisting pollinator yucca moths. Molecular Phylogenetics and Evolution 21:117-127

Bradley, C., C. Wallis, and C. Wershler. 2006. Plant species at risk on AAFC Onefour, Alberta. Prepared for Agriculture and Agri-Food Canada, Regina, SK. vi + 107 pp.

COSEWIC 2002. COSEWIC assessment and update status report on the yucca moth Tegeticula yuccasella in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 24 pp.

COSEWIC 2006a. COSEWIC assessment and status report on the Non-pollinating Yucca Moth Tegeticula corruptrix in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 24 pp.

COSEWIC 2006b. COSEWIC assessment and status report on the Five-spotted Bogus Yucca Moth Prodoxus quinquepunctellus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 31 pp.

COSEWIC 2010. COSEWIC Guidelines on Manipulated Populations. (Accessed September 6, 2016).

COSEWIC. 2013a. COSEWIC assessment and status report on the Yucca Moth Tegeticula yuccasella, Non-pollinating Yucca Moth Tegeticula corruptrix and the Five-spotted Bogus Yucca Moth Prodoxus quinquepunctellus in Canada.

COSEWIC. 2013b. COSEWIC assessment and status report on the Soapweed Yucca glauca in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 34 pp. Csotonyi, J.T., and D. Hurlburt. 2000. Update COSEWIC status report on the Soapweed Yucca glauca in Canada, in COSEWIC assessment and update status report on the Soapweed Yucca glauca in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa.12 pp.

Davis, D.R. 1967. A revision of the moths of the subfamily Prodoxinae. Bulletin of the United States National Museum 255:1-170.

Dodd, R J., and Y. Linhart. 1994. Reproductive consequences of interactions between

Yucca glauca (Agavaceae) and Tegeticula yuccasella (Lepidoptera) in Colorado. American Journal of Botany 81:815-825.

Environment Canada. 2011. Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. 15 pp + Appendix.

Environment Canada. 2012. Amended Recovery Strategy for the Tiny Cryptantha (Cryptantha minima) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. vii + 38 pp.

Foreman, K., J. Nicholson, L. Matthias, and J. Chandler. 2006. 2004 Pinhorn Grazing Reserve Soapweed population survey. Alberta Sustainable Resource Development, Fish and Wildlife Division, Alberta Species at Risk Report No. 111, Edmonton, Alberta. 9 pp.

Fuller, O.S. 1990. Factors affecting the balance of co-operation and conflict between the Yucca Moth, Tegeticula yuccasella and its mutualist, Yucca glauca. Ph.D. thesis, University of New Mexico, Albuquerque, NM. 91 pp.

Hurlburt, D. 2001. Status of Soapweed (Yucca glauca) in Alberta. Alberta Environment,

Fisheries and Wildlife Management Division, and Alberta Conservation Association, Wildlife Status Report No. 35, Edmonton, Alberta. 18 pp.

Hurlburt, D. D. 2004. Persistence of the mutualism between Yuccas and Moths at the northern edge of range. Ph. D. thesis, University of Alberta, Edmonton, Alberta. 179 pp.

Hurlburt, D.D. 2007. Yucca moth (Tegeticula yuccasella) population assessment and monitoring methodology at AAFC Onefour Research Substation, Alberta in 2007 – Final Report. Prepared for Agriculture and Agri-Food Canada, Regina, SK. 42 pp.

Hurlburt, D. 2011. Field verification report on Soapweed (Yucca glauca) and Yucca Moths (Tegeticula yuccasella, Tegeticula corruptrix, Prodoxus quinquepunctellus) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, ON. 7 pp.

James, M. L. 1998. Limits on the exploitation of the Yucca-Yucca Moth mutualism. M.Sc. thesis, University of Alberta, Edmonton, AB. 107pp.

Keeley, J.E., and A. Meyers.1985. Effect of heat on seed germination of southern Yucca species. Southwestern Naturalist 30:303-304.

Kerley, G.I.H., F. Tiver, and W.G. Whitford. 1993. Herbivory of clonal populations: cattle browsing affects reproduction and population structure of Yucca elata. Oecologia 93:12-17.

Marr, D.L., J. Leebens-Mack, L. Elms, and O. Pellmyr. 2000. Pollen dispersal in Yucca filamentosa (Agavaceae): The paradox of self-pollination behavior by Tegeticula yuccasella (Prodoxidae). American Journal of Botany 87:670-677.

Milner,B.J.1977.Habitat of Yucca glauca Nutt. in southern Alberta. M.Sc. thesis, University of Alberta, Edmonton, Ab. 72 pp.

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Pellmyr, O. 1999. Systematic revision of the Yucca Moths in the Tegeticula yuccasella complex (Lepidoptera: Prodoxidae) north of Mexico. Systematic Entomology 24:243-271.

Pellmyr, O., J. Leebens-Mack,and C.J. Huth. 1996. Non-mutualistic yucca moths and their evolutionary consequences. Nature 380:155-156.

Perry, J. 2001. Indirect mutualism: how ants affect the Yucca-Yucca Moth relationship. BSc (Honours) thesis, University of Alberta, Edmonton. 34 pp.

Perry, J. C., E.B. Mondor, J.F. Addicott. 2004. An indirect mutualism: ants deter seed predators from ovipositing in yucca fruit. Canadian Journal of Zoology 82: 823-827.

Powell, J. A. 1992. Interrelationships of yuccas and yucca moths. Trends in Ecology and Evolution 7(l):10-15.

Powell, J.A. 2001. Longest insect dormancy: Yucca Moth larvae (Lepidoptera: Prodoxidae) metamorphose after 20, 25, and 30 years in diapause. Annals of the Entomological Society of America 94:677-680.

Saskatchewan Conservation Data Center. 2015. Saskatchewan Vascular Plants Taxa List. Regina, Saskatchewan. (Accessed: August 10, 2016).

Snell, R.S. 2004. Direct and indirect effect of ants on moth/yucca interactions: how additional species affect the costs/benefits in an obligate mutualism. M.Sc. thesis, University of Calgary, Calgary, Alberta.

Snell, R.S., and J.F. Addicott. 2008a. Limiting the success of stem borers (Prodoxus quinquepunctellus) in Yuccas: indirect effects of ants, aphids and fruit position. Ecological Entomology 33(1):119-126.

Snell, R.S., and J.F. Addicott. 2008b. Direct and indirect effects of ants on seed predation in moth/yucca mutualisms. Ecoscience 15(3): 305-314.

Personal communications

Johnson, D. Professor of Environmental Science, Canada Research Chair in Sustainable Grassland Ecosystems. University of Lethbridge. Lethbridge, Alberta.
Henderson, D. Grassland Ecologist. Environment and Climate Change Canada, Pacific Region, Kelowna, British Columbia.
Hurlburt, D. Independent Biological Consultant. Annapolis Royal, Nova Scotia.
Robertson, S. Wildlife Biologist. Alberta Environment and Parks, Medicine Hat, Alberta.
Linowski, C. Program Coordinator. Environmental Land Reclamation, Medicine Hat College. Medicine Hat, AB.
Nicholson, J. Senior Species at Risk Biologist. Alberta Fish and Wildlife, Medicine Hat, Alberta.
Sample, T. Previously: Coordinator, Rare Plant Rescue and PlantWatch. Nature Saskatchewan. Regina, Saskatchewan.
Vinge-Mazer, S. Botanist. Saskatchewan Conservation Data Center, Saskatoon, Saskatchewan.

Appendix A. Decision tree for determining the type of critical habitat identification based on biological criteria

This decision tree was developed by the Recovery Team for Plants at Risk in the Prairie Provinces, to guide the approach for identifying critical habitat for all terrestrial and aquatic prairie plant species at risk.

The first decision is regarding the quality of available information on the species occurrences in Canada, with the choice of accepting or rejecting any given occurrence for consideration as critical habitat based on three criteria.

The second decision is based on how well the habitat is defined. If habitat is not well defined, critical habitat consists of the area encompassing the occurrence and all natural landform, soil, and vegetation features within a 300 m distance of the occurrence.

For species that occupy well-defined and easily-delineated habitat patches, a third decision relates to the ease of detection of the species and the spatial and temporal variability of their habitat.

Decision tree:

1a. Occurrences have not been revisited for >25 years, or use imprecise and/or inaccurate geographic referencing systems, or the habitat no longer exists at that location to support the species (no critical habitat will be defined until more is known about the population and location)

1b. Occurrences have been relocated and revisited in the past 25 years, and habitat has been revisited in past 5 years to confirm it has the potential to support an occurrence, and geographic reference is accurate and precise (go to 2)

2a. Species is a generalist associated with widespread habitats, or a specialist that occupies dynamic disturbance regimes difficult to delineate as patches in space, or occupies habitat that is otherwise poorly defined (critical habitat area = occurrences + all natural landform, soil, and vegetation features within a 300 m distance of each occurrence)

2b. Species occupies well-defined and easily delineated habitat patches in space (go to 3)

3a. Habitat patches are spatially static in the medium to long term, or species is easy to reliably detect (critical habitat area = occupied habitat patches + all natural landform, soil, and vegetation features within a distance of 300 m of the habitat patches)

3b. Habitat patches are spatially dynamic in the medium to long term, or species is difficult to reliably detect (critical habitat area = occupied and potentially occupied habitat patches + all natural landform, soil, and vegetation features within a distance of 300 m of the habitat patches).

Notes

Criterion 1a is consistent with NatureServe guidelines for data quality, in that records >25 years old with no subsequent revisit record are least accurate.

Criterion 1b is consistent with SARA Sections 46 and 55 which require reporting on progress towards meeting recovery objectives at five-year intervals.

Criteria 2a, 3a and 3b are consistent with recommendations in Appendix D. In some cases a large barrier exceeding 150 m in width creates a discontinuity in the natural habitat within the 300 m like a major river channel or cultivated field. These barriers effectively overwhelm other edge effects at the distal end of the 300 m, or prevent effective dispersal of the plant at the proximal end closest to the occurrence. In these particular cases, some patches of natural vegetation on natural landforms within a distance of 300 m, but discontinuous from the habitat occupied by the plants, may be exempt from consideration as critical habitat.

Criterion 3 will be applied only if information is sufficient to classify the habitat as spatially static or dynamic and to classify the species' detectability as easy or difficult. If information is not sufficient, critical habitat will be identified as per 2a until studies are completed to obtain the necessary information.

Appendix B. Effects on the environment and other species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s (FSDS) goals and targets.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the strategy itself, but are also summarized below in this statement.

This recovery strategy will benefit biodiversity in Canada by promoting the recovery of the Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth. The potential for the strategy to inadvertently lead to adverse effects on other species was considered. The SEA concluded that this strategy will clearly benefit the environment and will not entail any significant adverse effects. Refer to the Species Biology, Threats, and Critical Habitat sections found in the Recovery Plan for the Soapweed and Yucca Moth in Alberta (2012-2022) for more information (Part 2).

The conservation approaches identified in this recovery strategy will not jeopardize the survival, distribution, or abundance of other species; rather, this recovery strategy has the potential to benefit several rare and endangered species. Soapweed is an obligate host for the Strecker’s Giant Skipper (Megathymus streckeri), a rare butterfly known to occur in Canada only at the Onefour location (Hurlburt 2007). Management and research activities would have a positive effect on federally-listed species including the Swift Fox (Vulpes velox, threatened), Burrowing Owl (Speotyto cunicularia, endangered), Sprague’s Pipit (Anthus spragueii, threatened), Loggerhead Shrike (Lanius ludovicianus excubitorides, threatened), Eastern Yellow-bellied Racer (Coluber constrictor flaviventris, threatened), Greater Short-horned Lizard (Phrynosoma hernandesi, endangered), Tiny Cryptantha (endangered), Small-flowered Sand Verbena (endangered) and Smooth Goosefoot (Chenopodium subglabrum, threatened). Consequently, the promotion of Soapweed, Yucca Moth, Non-pollinating Yucca Moth and Five-spotted Bogus Yucca Moth recovery will certainly assist the conservation of these rare and at risk species as well as a wide range of native plant species that occur in the area.

Appendix C. Critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth in Canada

Table 5. Critical habitat units (10 x 10 km standardized UTM squares) within which critical habitat for Soapweed, Yucca Moth, Non-pollinating Yucca Moth, and Five-spotted Bogus Yucca Moth is found in Alberta. Critical habitat occurs where the criteria described in Section 7.1 are met.
Population10 x 10 km Standardized UTM grid square IDg
ProvinceUTM Grid Square Coordinatesh
Easting
UTM Grid Square Coordinatesh
Northing
Land Tenurei
Pinhorn Grazing Reserve12UWV13Alberta5100005430000Non-federal Land
Onefour Research Ranch12UWV42Alberta5400005420000Non-federal Land

g Based on the standard UTM Military Grid Reference System, where the first 2 digits and letter represent the UTM Zone, the following 2 letters indicate the 100 x 100 km standardized UTM grid followed by 2 digits to represent the 10 x 10 km standardized UTM grid. The last 2 digits represent the 1 x 1 km standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (for more information on breeding bird atlases).

h The listed coordinates are a cartographic representation of where critical habitat can be found, presented as the southwest corner of the 10 x 10 km standardized UTM grid square containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

i Land tenure is provided as an approximation of the types of land ownership that exist at the critical habitat units and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land parcel information.

Appendix D. Rationale for including a distance of 300 m from plant occurrences in critical habitat identification

Terrestrial plants are sessile and their propagules (seeds, rhizomes, or stolons) are more dispersal-limited than the offspring of mobile organisms like vertebrates and invertebrates. Terrestrial plants also compete for the same primary resources of space aboveground for sunlight and gas exchange, and space belowground for water and nutrients. To protect habitat required for survival or recovery of a plant, it is also necessary to protect the current distribution of these resources where the plants are known to occur. Any human activity that could disrupt this otherwise natural distribution of resources could effectively destroy the critical habitat of a plant species at risk. Often human activity may occur at one site but the effects of that activity occur at another site. Alternatively, the effect of human activity may decline with distance from the site where the activity took place, or the effects of human activity could be cumulative over time (Ries et al. 2004). The question then becomes, what is a reasonable minimum distance from a plant species at risk that may encompass habitat required for its survival or recovery? The answer will define the area requiring protection as critical habitat under the Species at Risk Act (SARA).

Protection of habitat subject to Edge-effects of human activities

An area including a distance of 300 m from detectable occurrences will be critical to ensure long-term survival of plant populations.

Edge effects of soil disturbance

The only research to describe edge effects on short-term survival of plant species at risk indicated 40 m was the minimum distance needed to avoid negative impacts of road dust on plant health and population growth (Gleason et al. 2007); however, that was also the maximum distance at which measurements were made. In detailed reviews by Forman and Alexander (1998) and Forman et al. (2003), most roadside edge effects on plants resulting from construction and repeated traffic have their greatest impact within the first 30 to 50 m. However, salinity, nitrogen and hydrological effects could extend 100 to 200 m from a road, and invasive alien species may spread up to 1 km. Invasive alien species have the potential to competitively exclude plant species at risk, and alter the ecosystem such that the plant species at risk can no longer use the habitat. This particular threat may then destroy critical habitat, without some active restoration.

Hansen and Clevenger (2005) observed no decline in the frequency of invasive alien species up to 150 m away from roads and railways in a grassland environment, although sampling did not extend further than 150 m. Gelbard and Harrison (2005) concluded that edge effects of roads on the plant and soil habitat was such that invasive alien species could more readily establish and survive within 10 m of roads compared with plants up to 1000 m from roads. Of course, not all roads are the same and Gelbard and Belnap (2003) found that paved or graded roads tend to have a higher cover and richness of invasive alien species compared with 4 x 4 vehicle tracks. All classes of road created habitat for the dispersal and establishment of these species in roadside verges and 50 m beyond. The difference was that greater frequency of traffic and intensity of disturbance on improved roads increased the process of invasion.

The road density typical of the Canadian prairies is one road every 1.6 to 3.2 km. As such, it is unlikely that source populations for invasive alien species can be accurately identified beyond 800 m from roadside or cultivated field edges (the center of a 1.6 x 1.6 km section assuming it is surrounded by roads or cultivated lands). Considering that significant effects of invasive alien species can currently be detected up to 150 m from roads and other developed sites, but can occur >800 m from a source population, some compromise distance between 150 and 800 m seems reasonable to ensure the maintenance of critical habitat attributes.

Edge effects of atmospheric industrial emissions

Atmospheric emissions from industrial activity, including intensive agriculture, can lead to a cumulative deposition of nitrogen on surrounding soils. Elevated concentrations of nitrogen and sulphur become analytically detectable in plants and soils up to 1 to 2 km away (Meshalkina et al. 1996, Hao et al. 2006). It is not clear if these detectable increases in macronutrients are biologically meaningful, but since most prairie plant species at risk occupy nutrient-poor, early to mid-successional grassland habitats, any increase in soil nutrient availability is likely to intensify competition, speed succession, and eliminate habitat critical for the species survival.

Reich et al. (2001) observed an increase in the productivity of Hairy Prairie Clover (Dalea villosa) in response to nitrogen fertilizer, but in a mixed community any positive effect would be offset by the greater productivity response of other competing species. Kochy and Wilson (2001) observed nitrogen deposition in Elk Island National Park several kilometers downwind of petroleum refineries and an urban center to be 22 kg ha-1 year-1, while background rates in the wilderness at Jasper National Park were only 8 kg ha-1 year-1. These increased deposition rates appeared to promote forest encroachment at the expense of native grasslands at Elk Island, moreso than rates at Jasper. Experiments by Plassmann et al. (2008) found that low additions of nitrogen (15 kg ha-1 year-1) to sand dunes increased germination rates of annual plants from the seedbank, which risks depleting the seedbank and eliminating a species from a low-nitrogen site to which it is adapted.

Similar to the effects of industrial emissions, some invasive alien species like the legume sweet clover (Melilotus spp.) can elevate soil nitrogen through biological fixation and facilitate invasions by other invasive alien species (Jordan et al. 2008, Van Riper and Larson 2009). This particular plant has become one of the most widespread invasive alien species in the northern Great Plains, due initially to deliberate planting in roadside edges, forage crops, and other reclaimed areas (Lesica and DeLuca 2000). These findings reinforce the idea that an area greater than 150 m to avoid invasive alien legumes, and possibly greater to avoid negative effects of industrial nitrogen and sulphur emissions, is necessary to ensure the maintenance of habitat critical attributes for prairie plant species at risk.

Edge effects of fluid spills

Water, hydrocarbons or other fluids leaking from pipeline ruptures will have edge effects that vary greatly depending upon topography of the site. For example, an Alberta Energy Resources Conservation Board (ERCB) investigation during 2008 at CFB Suffield found a surface leak of crude oil spread 165 m along ungulate trails and ultimately covered 1200 m2 of native grassland, killing more than 200 migratory birds (ERCB Investigation Report 2009-06-18). A second incident investigated by ERCB involved a natural gas blowout that released “lower explosive levels” of gas at 100% within 50 m of a wellhead decreasing to 0% at 500 m. This incident also involved a spill of fluids up to 25 m from the wellhead that resulted in excavation and removal of 540 tonnes of soil for remediation (ERCB Investigation Report 2009-06-01). ERCB investigations elsewhere have found oil spills that spread 1.6 km across the surface from rupture points before clean-up could begin (ERCB Investigation Report 2007-05-09).

As plants are not mobile, flooding and inundation for any period of time may be sufficient to destroy critical habitat for several months, years, or decades. The probability of such a rupture is unknown, particularly in proportion to the density of all existing and planned pipelines, and in proportion to habitat availability and species at risk occupancy in the area. The risk of an irreversible change to the habitat is high, so the addition of pipelines within several hundred meters of plant occurrences should not be permitted.

Summary

All of the factors discussed above are potentially cumulative, particularly in the more industrialized parts of southern Alberta and south-western Saskatchewan. Industrial emissions, road construction, and fluid spills are logically co-located land use activities, and land spreading of agricultural wastes can add to the effects. Given the uncertainty regarding the outer distance for possible edge effects exceeding 150 meters, and the difficulty of identifying a point source for effects beyond 800 m, a precautionary approach is to include a distance of 300 m from the plant species at risk occurrences as habitat critical to survival of the species. This value of 300 m is simply twice the 150 m value for which published evidence indicates that significant negative effects can occur to the habitat of plant species at risk. A doubling of the 150 m value is intended to be precautionary to ensure critical habitat attributes are maintained.

Research is needed to more specifically address the edge-effects of major land use activities on habitat critical to survival of prairie plant species at risk. A smaller or larger distance may be suggested based on the results of that research, and changes to the definition of habitat critical to the survival of prairie plant species at risk could result from that work.

Literature cited

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Forman, R.T.T., and L.E. Alexander. 1998. Roads and their major ecological effects. Annual Review of Ecology and Systematics. 29: 207-231.

Forman, R.T.T., D. Sperling, J.A. Bissonette, A.P. Clevenger, C.D. Cutshall, V.H. Dale, L. Fahrig, R. France, C.R. Goldman, K. Heanue, J. A. Jones, F.J. Swanson, T. Turrentine, and T.C. Winter. 2003. Road ecology: Science and solutions. Island Press. Covelo CA.

Gelbard, J.L., and J. Belnap. 2003. Roads as conduits for exotic plant invasions in a semiarid landscape. Conservation Biology. 17: 420-432.

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Text Content Footnote

Footnote 1

These federally protected areas are: a national park of Canada named and described in Schedule 1 to the Canada National Parks Act , The Rouge National Park established by the Rouge National Urban Park Act , a marine protected area under the Oceans Act , a migratory bird sanctuary under the Migratory Bird Convention Act, 1994 or a national wildlife area under the Canada Wildlife Act see ss. 58(2) of SARA.

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Footnote 2

‘Naturally occurring’ refers to any population within the native range on naturally occurring habitat. It excludes horticultural populations or those that are dispersed by humans and established outside the native range or on unnatural habitats such as gardens.

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Footnote 3

Obligate mutualism refers to the interaction between two species where both species benefit from the association but in which at least one of the partners could perish in the absence of the other.

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Footnote 4

Maxillary tentacles are specialized mouthparts present in female pollinating yucca moths. Their primary function is to purposely aid in the collection and transport of Soapweed pollen (Davis 1967).

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Footnote 5

Enlarged pedicels indicate that an individual flower was pollinated by a moth and had initiated a degree of fruit development prior to abscission (Hurlburt 2011).

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Footnote 6

A clone refers to a group of plants originating by vegetative propagation from a single parent.

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Footnote 7

Reproductive capacity for Soapweed refers to the number of flowers and fruit produced in a given year. Reproductive capacity for Yucca Moth refers to an increase in individuals. Fruit emergence holes and Soapweed fruit production has been used as an index of Yucca Moth abundance.

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Footnote 8

Soapweed population data known to Environment and Climate Change Canada as of August 2016.

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Footnote 9

Occurrence refers to an individual Soapweed plant as recorded in the field

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