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 2 - Alberta Soapweed and Yucca Moth Recovery Plan 2012-2022, prepared by the Alberta Environment and Sustainable Resource Development
Alberta's species at risk program
Alberta Species at Risk Recovery Plan No. 25
Prepared by Alberta Environment and Sustainable Resource Development
Moths on Soapweed Plant - © Dan L. Johnson
Soapweed Habitat - © Joyce Gould
Soapweed in Bloom - © Joyce Gould
For copies of this report, contact:
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This publication may be cited as:
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.
Albertans are fortunate to share their province with a diverse variety of wild species. Populations of most species of plants and animals are healthy and secure. However, a small number of species are either naturally rare or are now imperiled because of human activities. Recovery plans establish a basis for cooperation among government, industry, conservation groups, landowners and other stakeholders to ensure these species and populations are restored or maintained for future generations.
Alberta's commitment to the Accord for the Protection of Species at Risk and to the National Framework for the Conservation of Species at Risk, combined with requirements established under Alberta's Wildlife Act and the federal Species at Risk Act , has resulted in the development of a provincial recovery program. The overall goal of the recovery program is to restore species identified as Threatened or Endangered to viable, naturally self-sustaining populations within Alberta. The policy document: Alberta's Strategy for the Management of Species at Risk (2009-2014) provides broader program context for recovery activities.
Alberta species at risk recovery plans are prepared under the supervision of the Species at Risk Program, Alberta Environment and Sustainable Resource Development. This often includes involvement of a recovery team composed of a variety of stakeholders including conservation organizations, industry, landowners, resource users, universities, government agencies and others. Membership is by invitation from the Director of Wildlife Management, and may include representation from the diversity of interests unique to each species and circumstance. Conservation and management of these species continues during preparation of the recovery plan.
The Director of Wildlife Management provides these plans as advice to the Minister responsible for fish and wildlife management. Alberta's Endangered Species Conservation Committee also reviews draft recovery plans, and provides recommendations to the Minister. Additional opportunities for review by the public may also be provided. Plans accepted and approved for implementation by the Minister are published as a government recovery plan. Approved plans are a summary of the Department's commitment to work with involved stakeholders to coordinate and implement conservation actions necessary to restore or maintain these species.
Recovery plans include three main sections: background information that highlights the species' biology, population trends, and threats; a recovery section that outlines goals, objectives, and strategies to address the threats; and an action plan that profiles priority actions required to maintain or restore the Threatened or Endangered species. Each approved recovery plan undergoes regular review, and progress of implementation is evaluated. Implementation of each recovery plan is subject to the availability of resources, from within and from outside government.
Donna Hurlburt provided valuable technical information and advice during the preparation of this updated plan. Special thanks to students and instructors from the Environmental Land Reclamation Program at Medicine Hat College for monitoring of the Pinhorn soapweed/yucca moth population in the fall of 2009, 2010, and 2011 and providing monitoring data for the recovery plan update. Thank you to Ian Walker, manager of the AAFC Onefour Research Substation, and his staff, for providing hospitality, logistical support, and valuable seasonal information about the Onefour soapweed population. We would also like to extend our thanks to the Etzikom Windmill Museum for its partnership and contribution to helping promote and enhance public awareness of soapweed and yucca moths by housing a living display of the species’ along with interpretive signage.
Funding and support for the preparation of the recovery plan was provided by the Species at Risk Program of Alberta Environment and Sustainable Resource Development and recovery team member organizations and individuals. This recovery plan update was developed from the original plan by Kathryn Romanchuk in consultation with Joel Nicholson and others.
Soapweed (Yucca glauca), commonly known as yucca, is an arid-region perennial that grows as a single rosette or cluster of rosettes of long, narrow, spear-shaped leaves. A tall flowering stalk grows from the centre of each rosette and produces large, white flowers. The yucca moth (Tegeticula yuccasella) is a small, white, nocturnal moth. Soapweed and yucca moths have an obligate mutualistic relationship such that neither species can survive and sexually reproduce without the other; although soapweed can reproduce asexually on its own. Moth larvae feed only on soapweed seeds and soapweed can only produce seeds if pollinated by yucca moths. A number of factors, including ungulate and insect herbivory, uncoupling of interactions among soapweed and yucca moths, pollen limitation, habitat destruction or alteration, and collection of soapweed for horticultural or medicinal uses may threaten the persistence of these species
In February 2003, the Minister of Environment and Sustainable Resource Development approved the listing of soapweed and yucca moths as Endangered in Alberta. Soapweed was listed as Endangered under Alberta’s Wildlife Act in November 2007; whereas yucca moth has not yet been listed. These designations were based on the species’ occurring at only two sites and occurring over a small area, and a small and declining yucca moth population at one of the locations (Pinhorn Grazing Reserve). In addition, both sites are isolated from soapweed and yucca moth populations in the United States.
The Initial Conservation Action Statement recommended formation of a multi-stakeholder recovery team to produce a recovery plan. The Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011 was produced with the goals to:
- maintain the existing habitat and distribution of soapweed and yucca moths in Alberta;
- maintain naturally, self-sustaining populations of soapweed and yucca moths at the Onefour site; and
- increase the reproductive capacity of soapweed and yucca moth populations at the Pinhorn site.
Implementation of recovery actions outlined in that plan resulted in progress being made on all three goals. The conservation and management activities undertaken assisted in maintaining the existing habitat and soapweed and yucca moth populations at both locations in Alberta, and enhanced the yucca moth population at the Pinhorn site; although it still remains uncertain as to whether or not the reproductive rate is indicative of a viable population.
This updated version, the Alberta Soapweed and Yucca Moth Recovery Plan 2012-2022, represents a continuation and refinement of recovery and conservation efforts for soapweed and yucca moths in Alberta. The goals and objectives of this plan will be achieved through implementation of the following specific strategies:
- conservation and management of soapweed and yucca moth populations, and management of native ungulate populations to reduce losses due to herbivory;
- conservation and management of habitat in order to maintain the quality and quantity of habitat used by soapweed and yucca moths;
- provision of information and educational materials to the public and stakeholders to promote the conservation of soapweed and yucca moths;
- research to elucidate aspects of the life history of soapweed and yucca moths to better understand how to conserve these species;
- acquisition of resources needed to implement the recovery plan; and
- development of provincial regulations to protect soapweed and yucca moths and their habitat. It is expected that implementation of activities to conserve soapweed and yucca moths, combined with stakeholder cooperation and commitment, will allow for the long-term persistence of these two species in Alberta.
1.1 Provincial and Federal status
In February 2003, the Minister of Alberta Environment and Sustainable Resource Development (AESRD) approved the listing of soapweed (Yucca glauca) and yucca moth (Tegeticula yuccasella) as Endangered under the Wildlife Act in Alberta on the recommendation of the Alberta Endangered Species Conservation Committee (ESCC). Soapweed was listed as Endangered in November 2007; whereas yucca moth has not yet been listed.
The designation for soapweed was based on a small distribution and decline of the Alberta population, combined with a limited occurrence of the species at only two sites. In addition, populations at both sites are isolated from soapweed populations in the United States (Hurlburt 2001). The yucca moth appears to be declining in one of the two Alberta populations (Pinhorn), and both populations are isolated from moth populations in the United States (Hurlburt 2001).
A recovery plan was developed to set goals, objectives, strategies, and management actions to guide the management of these two species. The focus of the initial plan was the identification and conservation of existing populations. The Initial Conservation Action Statement for soapweed/yucca moth further stated that government regulated activities and land use management systems should be strengthened. As soapweed and yucca moths have an obligate mutualistic relationship, the development of a joint recovery plan for these two species was both practical and appropriate.
In 2006, the initial Recovery Plan for Soapweed and Yucca Moth in Alberta, 2006-2011 (Alberta Soapweed and Yucca Moth Recovery Team 2006) was developed to meet provincial
requirements for recovery planning as described in Alberta’s Wildlife Act . The updated plan, which will guide recovery efforts through 2022, represents a continuation and refinement of recovery and conservation efforts for soapweed and yucca moths in Alberta.
In May 2000 and 2002, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated soapweed and the yucca moth as Threatened and Endangered, respectively, due to their restricted occurrence and distribution in Canada (COSEWIC 2000, 2002, 2005). Both species are protected under the federal Species at Risk Act (SARA). The federal recovery strategy for soapweed and yucca moths was approved, and subsequently published in 2011 (Environment Canada 2011).
In December 2007, two additional moth species in Alberta that are entirely reliant on the mutualistic relationship between soapweed and yucca moths, the five-spotted bogus yucca moth (Prodoxus quinquepunctellus) and the non-pollinating yucca moth (Tegeticula corruptrix), were listed as Endangered under the federal Species at Risk Act (Environment Canada 2011). Given these species are not currently listed under Alberta’s Wildlife Act , they are not being directly addressed in this provincial recovery plan.
1.2 Recovery team
At the direction of the Minister of Environment and Sustainable Resource Development, the Soapweed and Yucca Moth Recovery Team was initiated in October 2003 by the Director of Wildlife Management. The team’s primary responsibility was to develop the initial provincial recovery plan. Recovery team membership included parties likely to affect or to be affected by recovery actions, and consisted of the following member organizations: Alberta Environment and Sustainable Resource Development, Alberta Tourism, Parks and Recreation (Alberta Conservation Information Management System), Agriculture and Agri-Food Canada, University of Lethbridge, Alberta Native Plant Council, and the Pinhorn Grazing Association.
2.0 Species biology
2.1 Life history and adaptations
Soapweed (commonly known as yucca) is an arid-region perennial that grows as a single rosette or cluster of rosettes of long, narrow, spear-shaped leaves 25 to 40 cm long (Kingsolver 1984). A rosette may reproduce asexually resulting in a clone plant growing near the original rosette. An inflorescence (flowering stalk) 30 to 85 cm tall grows from the centre of each rosette and produces 15 to 75 large, fleshy, downward-nodding flowers (Kingsolver 1984). Flowers are generally white or pinkish-white (Kingsolver 1984). Soapweed plants mature at 15 to 20 years of age and flower only every 2 or 3 years. Individual rosettes flower only once and die after flowering (Kingsolver 1984). The plant can reproduce sexually through the production of seeds or asexually through the production of rhizomes (Hurlburt 2001). Plants are tolerant of self-pollination but still require moths for this process to occur (Hurlburt 2004). Flowers that are pollinated become fruit and mature into woody pods during July and August. Seedpods open in September and release thin, flat, black seeds (Kingsolver 1984; Kershaw et al. 2001). Seeds are primarily gravity dispersed and fall near the parent plant, creating the clumped distribution of this species (D. Hurlburt, pers. comm.). Seeds have a low germination rate and are viable only for one year (Webber 1953; Milner 1977), resulting in a seed bank that cannot ensure the persistence of the species (ASRD 2002).
Yucca moths are small night-flying moths. Forewings are generally white with a wingspan of 18 to 28 mm (Pellmyr 1999). Hind wings are brownish-grey, gradually turning white toward the hind corner (Pellmyr 1999). Females have fully developed tentacles that they use to gather pollen and to pollinate soapweed flowers (ASRD 2002). Yucca moths do not appear to be strong flyers and probably cannot disperse over long distances (Hurlburt 2001).
Soapweed and yucca moths have an obligate mutualistic relationship such that neither species can survive on a long-term basis and/or reproduce sexually without the other. Moth larvae feed only on soapweed seeds and soapweed can only produce seeds if pollinated by yucca moths (Hurlburt 2001, 2002). Adult yucca moths emerge from the soil between mid-June and mid-July (Hurlburt 2004). After emergence, moths gather and mate in soapweed flowers that open at night (Riley 1892, Baker 1986, Addicott et al. 1990). Following mating, a female yucca moth collects pollen from one plant using her tentacles and typically flies to a flower of another plant. The female deposits her eggs next to the developing ovules (Aker and Udovic 1981; Addicott and Tyre 1995). She then actively transfers pollen using her tentacles. By pollinating the flower, the female ensures that seeds will develop and will provide food for her young (Kershaw et al. 2001). Adult moths do not feed and they die 3 to 5 days after emerging from the soil (Kingsolver 1984). Moth eggs hatch 7 to 10 days after they are laid. Upon hatching, larvae feed on developing seeds. Developing larvae may consume a significant number of seeds (D. Hurlburt, pers. comm.). Plants may develop strategies to reduce larval loads, however in Canada this is not the case as plants may even employ strategies to encourage high larvae production (Hurlburt 2004). After 50 to 60 days, larvae chew their way out of the yucca fruit leaving a distinct hole in the pod and drop to the ground via a silken thread (Riley 1892). Larvae burrow into the soil, spin a cocoon of silk and sand particles, and enter diapause (Davis 1967; Fuller 1990; Hurlburt 2001). After a minimum diapause of one year (range 1-4 years), larvae pupate and emerge from the soil as adults, typically coinciding with flowering by soapweed (Fuller 1990). This prepupal diapause is quite rare in insects. Larvae have low survival rates; up to 50% of larvae from Alberta populations commonly fail to pupate, and of those that do pupate, up to 50% die in the cocoon (D. Hurlburt, unpubl. data).
2.2 Habitat requirements
Soapweed is restricted to the Dry Mixedgrass Subregion (Hurlburt 2001). Plants primarily occur on eroded south- or east-facing coulee slopes with sparse vegetation (Milner 1977). Soils tend to be alkaline and regosolic (undeveloped) without a shallow hardpan (Milner 1977). Details on vegetation commonly associated with soapweed can be found in Milner (1977), Wershler and Wallis (1986), and Hurlburt (2001). The habitat requirements of yucca moths are less well understood. Yucca moths use soapweed flowers for mating and oviposition, but the selection habits of moths for specific flowers to undertake these activities are not known. Yucca larvae require soapweed fruit for feeding. Once larvae emerge from fruit, they burrow into the soil around the plant and remain dormant for up to four years (Fuller 1990; Hurlburt 2004). Generally, the upper 20 cm of soil in a radius of approximately 25 cm from the edge of the outermost leaves of the plant may harbour dormant larvae (D. Hurlburt, pers. comm.). Larvae are not likely to exist where there is no remaining evidence of decayed plants (D. Hurlburt, pers. comm.).
2.3 Population size, distribution, and trends in Alberta
The only naturally occurring populations of soapweed and yucca moths are found at two locations in southeastern Alberta. One site is near Onefour along the Lost River drainage within the boundaries of the Agriculture and Agri-Food Canada Onefour Research Substation. The second site is on the Pinhorn Grazing Reserve south of Manyberries (Figure 1). Both locations are on provincial land under lease to the federal government and to the Pinhorn Grazing Association, respectively. The Onefour site is within the boundaries of the Onefour Heritage Rangeland Natural Area designated by Alberta Tourism, Parks and Recreation (Parks Division).
Several isolated plants, presumably originating as transplants, occur in numerous gardens across southern Alberta (Fairbarns 1985; Hurlburt 2001). Of particular interest are several plants in the town of Etzikom at the Etzikom Windmill Museum and in Police Point Park in Medicine Hat that have been observed to produce fruit, suggesting moths are also present (D. Johnson and J. Nicholson, pers. obs.).
The extent of occurrence of soapweed and yucca moths in Alberta is 400 km2 and the area of occupancy is less than 2 km2. The Onefour and Pinhorn populations of soapweed and yucca
moth are isolated from one another by a distance of approximately 15 km. There is no evidence that moths migrate between populations, probably because yucca moths and seeds are not capable of long distance dispersal (Hurlburt 2001). The closest population in the United States is approximately 200 km from the Onefour population (ASRD 2002).
Population trends of soapweed are difficult to determine and have not yet been established. Variability in population size estimates over the years appears to be due to differences in survey techniques rather than a decline in population size (Csotonyi and Hurlburt 2000; Foreman et al. 2006). Similarly, population trends for the yucca moth in Alberta are unknown; several years of monitoring the yucca moth populations would be required in order for a population trend to be determined (ASRD 2002).
At the Onefour location soapweed occurs along approximately 2 km of coulee slope, and on the adjacent uplands, and along a stretch of coulee slope approximately 200 m in length at the Pinhorn site (Hurlburt 2001; ASRD 2002). A 1998 census of soapweed revealed a total of 29,577 plants (i.e., rosettes) (8903 clones) in Alberta (Csotonyi and Hurlburt 2000). Of these plants, 28,174 (8499 clones) occurred at the Onefour site and 1383 (404 clones) occurred at the Pinhorn site (Csotonyi and Hurlburt 2000). The number of larvae entering diapause in 1998 at Onefour was 255 (including males) with 75-90 (29-35%) expected to survive to become adults (Csotonyi and Hurlburt 2000). New information suggests survival could sometimes be significantly lower (18%) (Hurlburt 2004). No moths were observed at the Pinhorn site in 1998 or in 2002. The Onefour population has produced fruit each year since 1998, indicating that this population is reproducing sexually (D. Hurlburt, pers. comm.). Fruiting success of flowering plants at Onefour varied between 8-92 % from 1999-2002 (Hurlburt 2004). Prior to an inventory of the Pinhorn soapweed population in 2004, fruit had not been documented at that site since 1997 or earlier, suggesting that the plants were only reproducing asexually (Hurlburt 2004).
The soapweed/yucca moth population at Onefour has been studied extensively since 1998, while much less was known about the Pinhorn population, except that very little evidence of sexual reproduction had been noted at the site (Foreman et al. 2006). As a result, a comprehensive inventory of the Pinhorn site was conducted in 2004; this was the first detailed survey since the 1998 census. Results from the 2004 inventory revealed a much larger population of soapweed
plants than previously reported. Perhaps even more significantly, evidence of fruit production and larval emergence confirmed that both sexual reproduction of soapweed and reproduction of yucca moths were occurring at the Pinhorn site, albeit at an extremely low rate (Foreman et al. 2006). Fruit production could possibly have been about 15 times higher in 2004 than what was recorded, based on the number of enlarged pedicels that were observed, suggesting that
additional fruit had been produced but had been browsed (Foreman et al. 2006). This was the first evidence of fruiting success since at least 1997. Nevertheless, the limited number of yucca moths could have major implications for the long-term persistence of the soapweed and yucca moth populations at this site.
3.0 Threats and limiting factors
Several natural and human-caused threats may limit the distribution and population size of soapweed and yucca moths in Alberta and may lead to a decrease in one or both of these species. These include: ungulate and insect herbivory; the uncoupling of interactions between soapweed and yucca moths; pollen limitation; habitat loss, fragmentation, and degradation; the collection of soapweed plants for horticultural or medicinal use; and possibly the effects of wind. Many of the natural limiting factors, such as insect herbivory and weather events, are beyond the control of the Alberta Soapweed and Yucca Moth Recovery Team and this recovery plan.
It is believed that the Onefour soapweed/yucca moth population is more resilient to adverse events than the Pinhorn due to its large population size and because the Onefour population appears to be on a cyclic flowering/fruiting cycle, with periods of very high flowering years followed by low flowering years (D. Hurlburt, pers. comm.). During peak flowering at the Onefour site, it would be unlikely that most herbivory or weather events could have a significant impact on the soapweed population because there are numerous flowers spread over many different microclimates, allowing some to successfully produce seed. Pinhorn, on the other hand, is a smaller population, dispersed over a much smaller area. Thus, localized threats are thought to be able to have a bigger impact on the Pinhorn soapweed/yucca moth population (D. Hurlburt, pers. comm.).
3.1 Ungulate herbivory
Pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) are common herbivores of soapweed, removing individual flowers or entire inflorescences (Hurlburt 2001). Grazing of flowers and inflorescences reduces sexual reproduction in soapweed and yucca moths. Fewer flowers are available for moths to pollinate and to lay eggs in, and larvae compete for, and consume, most seeds. In addition, night-flying yucca moths rest within yucca flowers during the day, leading to inadvertent consumption of moths by grazing herbivores (Csotonyi and Hurlburt 2000). Soapweed plants can be heavily grazed by deer and antelope (range 1-100% of flowers across years; COSEWIC 2002), particularly during periods of drought when lower quality forage resources are available (Csotonyi and Hurlburt 2000; Hurlburt 2001, COSEWIC 2002).
In the southern United States, domestic livestock species are common herbivores of soapweed (Webber 1953; Hurlburt 2001). There is some evidence of livestock grazing on soapweed at the Onefour site; however, this appears to be restricted to soapweed plants occurring on upland habitat where cattle can access them easily. Soapweed plants on slopes are less likely to be grazed by livestock (COSEWIC 2002). Cattle grazing at the Onefour site is primarily restricted to winter use, with cows being removed prior to soapweed flowering. In two years (2000 and 2002) where cattle were not removed until 7 to 10 days after flowering, little impact was noted. However, extended periods of livestock grazing during the flowering season may result in considerable loss of inflorescences, and subsequently reduced fruit set (Hurlburt 2007).
Herbivory by native ungulates and/or cattle has been identified as a significant threat to the Pinhorn population of soapweed and yucca moths (Csotonyi and Hurlburt 2000; ASRD 2002, Foreman et al. 2006, D. Hurlburt, pers. comm.). An initiative in 2007 of fencing off three small areas supporting soapweed and using range cages to cover individual plants has proven to be an effective method of protecting a small proportion of the soapweed and yucca moth populations from the impacts of ungulate herbivory at this site (C. Linowski, pers. comm.; Environment Canada 2011).
3.2 Horticultural and medicinal uses
Previous collection of soapweed is known because of its occurrence in household gardens across southeastern Alberta. However, all plants may not originate from wild stock as soapweed is available at garden centres for purchase. Soapweed is also a common component in a variety of herbal remedies and drugs used to treat a number of ailments including arthritis, gout, cystitis, and skin inflammations (Hurlburt 2001). Soapweed roots contain high concentrations of saponins (a chemical used in soaps, hence “soapweed”) that are precursors to the steroid cortisone and have anti-inflammatory properties. Removal of plants or seeds for horticultural or medicinal use could threaten the viability of the Alberta population, through a loss of plants and potentially viable seeds (Hurlburt 2001). Furthermore, removal of plants could result in the death of any yucca moths or larvae residing within soapweed flowers or fruit, and disturbance to the soil around the plant during removal could threaten the survival of dormant yucca moth larvae.
3.3 Habitat loss, fragmentation, and degradation
Both the Onefour and Pinhorn sites are on public land and unlikely to be at risk of conversion (e.g., cultivation). However, other activities such as oil and gas activity could result in the loss or degradation of habitat supporting soapweed and yucca moths. At the Onefour site all dispositions (e.g., oil and gas) must receive Ministerial consent given this sites’ occurrence within the proposed boundaries of the Onefour Heritage Rangelands Natural Area (Section 13 of the Wilderness Areas, Ecological Reserves, Natural Areas and Heritage Rangelands Act ). Recently, protective notations have been placed on both soapweed/yucca moth locations, restricting development within the boundaries of critical habitat identified for the species (see Figures 2 and 3 under Section 4.2). Additionally, the Onefour site is under lease to the federal government resulting in additional potential restrictions on surface developments.
There is considerable public interest in these species. Both sites are accessible by road and are often visited daily during the summer (Hurlburt 2001; COSEWIC 2002; Hurlburt 2007). Plants and moths may be threatened by off-road traffic through direct trampling of plants (Hurlburt 2001). Off-road vehicles also may damage the soil crust leading to an increase in erosion (Wershler and Wallis 1986) or may harm dormant larvae in the soils around plants. At both locations, there have been several observations of vehicles parked near or among soapweed plants and occasionally of vehicles driving over plants (D. Johnson and D. Hurlburt, pers. obs.).
3.4 Pollen limitation
Alberta populations of soapweed show little or no fruit production in some years (< 1% of flowers), low pollination, and low emergence of moth larvae from fruit (Hurlburt 2001). These characteristics are atypical of most soapweed populations in the southern United States. One explanation for these differences is that Alberta populations are pollen-limited. Pollen limitation may be due to low temperatures that restrict moth activity (Dodd and Linhart 1994) or to low abundance of moths. Pollen limitation may also occur if flowering by soapweed is unpredictable, does not occur annually, or does not coincide with moth emergence. Pollen limited plants either produce no fruit and seeds or may produce a higher percentage of asymmetrical fruit. At Onefour, 1-2% of fruit tend to be misshapen and have small numbers of viable seeds, providing evidence of pollen limitation (Hurlburt 2001, 2004). Low numbers of moths and minimal fruit production at the Pinhorn site may suggest that this population is also pollen limited (D. Hurlburt, pers. comm.).
3.5 Uncoupling of interactions between Soapweed and Yucca Moths
Mutualism between soapweed and yucca moths requires that moths must be present when soapweed is flowering. Flowering of Alberta populations of soapweed is highly asynchronous resulting in a large number of plants flowering earlier or later than average. For soapweed, this results in flowers receiving fewer visits by pollinators, having lower rates of pollen deposition, and having smaller potential for outcrossing. For yucca moth, this results in low recruitment due to decreased numbers of flowers in which to lay eggs and carry out its reproductive cycle (Hurlburt 2001).
3.6 Insect herbivory
Another moth, the non-pollinating yucca moth (T. corruptrix), lays its eggs in soapweed fruit but does not pollinate the plant. These non-pollinating moths may negatively impact soapweed and yucca moths by depositing enough eggs that many soapweed seeds are consumed by their larvae, limiting the sexual reproduction of the yucca plant (COSEWIC 2006). In Alberta, T. corruptrix larvae can consume up to 40% of seeds (Hurlburt 2001). The five-spotted bogus yucca moth (Prodoxus quinquepunctellus) lays its eggs in the flowering stalks of soapweed but does not appear to impact the plant (D. Hurlburt, pers. comm.; COSEWIC 2006a).
Ants are common on soapweed plants and negatively impact plants by foraging on the buds, causing premature shedding of those buds. In Alberta, some plants lose up to 90% of their buds through ant damage, resulting in fewer flowers for moths to pollinate and lay eggs in (COSEWIC 2002). Ants also may kill yucca moths that reside in flowers. Some species of grasshoppers also forage on soapweed and often consume the reproductive parts of the flower. Hurlburt (2001) reported that grasshoppers damaged 50% of the flowers on the upland prairie flats at the Onefour site in 1999.
Periods of intense wind can result in the loss of flowers and fruit, greatly reducing the reproductive success of soapweed and yucca moths. As an example, at the Pinhorn site in 1999, over 50% of the flowers were lost due to high winds. Windstorms also may limit the ability of moths to fly among plants to lay eggs and to pollinate other soapweed plants (Hurlburt 2001).
4.0 Critical habitat
Critical habitat is a legal designation under Canada’s Species at Risk Act (SARA), and is defined as:
“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” ( Species at Risk Act 2002 s. 2).
Alberta legislation has no comparable habitat regulation. However, a federal designation of Critical Habitat could lead to the need for changes in Alberta’s land and habitat management to ensure effective protection of such designated habitat. The initial recovery team provided recommendations to the federal government on critical habitat descriptions and they were adopted in the national recovery strategy (see Environment Canada 2011). The following subsections describe this more thoroughly.
4.1 Description of critical habitat for Soapweed and Yucca Moths
Soapweed is restricted to the Dry Mixedgrass Subregion. This is a region characterized by extremes with a low annual precipitation, usually between 260 mm - 280 mm. Warm summer temperatures (average 16° C) and a high average wind speed translate into a high rate of evaporation throughout the summer months (Hurlburt 2001). The regional frost-free season (100-120 days) and growing season (180-200 days) are long for the Canadian interior plains (Fairbarns 1984). There are approximately 2200 daylight hours with bright sunshine, making this one of the sunniest regions in Canada (Hurlburt 2001).
As expected, soapweed at Onefour and Pinhorn primarily occurs on eroded south or east facing coulee slopes with sparse vegetation (Milner 1977), although plants have been observed on the upland prairie flats. Coulee slope aspects range from 34º (northeast) - 220º (south-southwest) (Hurlburt 2001). Soapweed favours soil that is alkaline and regosolic (undeveloped) without shallow hardpan (Milner 1977; Fairbarns 1985).
4.2 Identification and rationale for the amount and arrangement
Soapweed exists naturally at two locations in Alberta; the Onefour and Pinhorn sites (as described in Section 2.3). The boundaries of critical habitat on the maps represent the perimeter of the soapweed populations. As a rule, the plants occur in lower densities towards the outside of the polygon, so this area should accommodate population expansion to occur. Because soapweed does not occur naturally outside of these locations and the amount of activity in the region is relatively low, identifying critical habitat outside of these boundaries for protection is not warranted. Thus, the 182 ha at the Onefour site and the 2.65 ha at the Pinhorn site outlined by the polygonal maps can be considered the extent of the critical habitat for soapweed in Canada (see Figure 2 and Figure 3 below). The boundaries will be reassessed periodically to allow for more critical habitat designation if the population expands.
Because yucca moths have an obligate mutualistic relationship with soapweed, the critical habitat should be considered the same for both species. Protection measures related to critical habitat of soapweed will also ensure protection of critical habitat for the yucca moth.
4.3 Critical habitat coordinates
Range coordinates of soapweed site locations have been collected and are available to support appropriate conservation and management of the soapweed population in Alberta. However, the specific locations of critical habitat are not identified in this recovery plan so as to minimize potential human disturbance of the sites and protect the species. Range coordinates may be made available to individuals and organizations as needed; i.e. for specific declared purposes related to approved recovery related conservation, management, and research initiatives.
4.4 destruction of critical habitat
Activities that destroy critical habitat for soapweed include anything that would risk conversion of the landscape. This would include cultivation or oil and gas activity such as drilling, conversion for wells or pipelines, or building roads.
Plants and moths may be damaged by off-road traffic through direct trampling of plants (Hurlburt 2001). Off-road vehicles may also increase potential for erosion (Wershler and Wallis 1986).
4.5 Effective protection of critical habitat
Both soapweed/yucca moth sites in Alberta have some protections in place from threats to the species. The Onefour site falls within a Heritage Rangeland Natural Area, which is afforded some protections under the Wilderness Areas, Ecological Reserves, Natural Areas and Heritage Rangelands Act, R.S.A. 2000. The Act limits using off-highway or highway vehicles (except on roads), pollution, destroying or damaging plant/animal life, garbage disposal, etc. The federal government also manages the Onefour site; thus it is treated as federal land and the SARA protections would apply. The Pinhorn site is at low risk for conversion as it is on Alberta public land. Protective notations have now been placed on both soapweed/yucca moth locations which will ensure that industrial users are not allowed to develop within the boundary of critical habitat (J. Nicholson, pers. comm.). See section 8.0 for further clarification of recovery actions for protecting critical habitat.
5.0 Knowledge gaps and research priorities
Translocation is one management option for increasing fruit production at the Pinhorn site (see Section 8.0). Thus, research needs to be concentrated on translocation methods and ensuring moth survival. It would be beneficial to conduct research on the factors affecting variation in flowering, fruit production, and moth emergence to help elucidate population dynamics of these species to determine the timing of the translocations. It is also important to know what affects larval survival of yucca moths to help maintain viable populations of this species. In particular, this study would be useful to inform the method for translocating moths to the Pinhorn site. This may be best accomplished by conducting a formal population viability analysis on the yucca moth.
As previously mentioned, there are two other moth species in Alberta that are obligately dependent on soapweed plants, the five-spotted bogus yucca moth and the non-pollinating yucca moth. Given these species’ similar requirements as yucca moths, it is believed that the conservation initiatives outlined in this recovery plan should also address the needs of these other moth species. However, when resources become available, inventories for the five-spotted bogus yucca moth and non-pollinating yucca moth could be pursued.
6.0 Recent recovery and conservation efforts
The initial Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011 outlined strategies and actions necessary for the recovery and conservation of soapweed and yucca moths in Alberta. Since its inception, significant progress has been made on implementation of the plan. Initiatives have focused on population monitoring, recovery actions, and information and outreach. Key efforts include:
- An inventory of the Pinhorn soapweed/yucca moth population in 2004 to determine the size of the population, document any evidence of fruit production and larval emergence, and assess the extent of herbivory occurring at the site (see Foreman et al. 2006);
- Installation of exclosures at the Pinhorn site in spring 2007 to protect a portion of the soapweed population from ungulate herbivory; three areas supporting soapweed were fenced off and 40 range cages were installed to cover individual plants;
- Translocation of yucca moth larvae from the Etzikom Windmill Museum population to the Pinhorn site in 2008;
- Monitoring of the soapweed/yucca moth population at the Pinhorn site in 2009, 2010, and 2011 by students in the Environmental Land Reclamation Program at Medicine Hat College as part of a cooperative program with the college;
- Ongoing seasonal observations of the soapweed population at the Onefour site by managers and staff of the AAFC Onefour Research Substation;
- Development of standardized population survey and monitoring methodologies for soapweed and yucca moths at the Onefour site (see Hurlburt 2007);
- Installation of interpretive signage at the Etzikom Windmill Museum in Etzikom, Alberta in front of a living display of soapweed plants and yucca moths to promote education and conservation of the two species;
- Placement of protective notations (PNTs) on both the Onefour and Pinhorn soapweed/yucca moth sites as a measure to protect critical habitat; and
- Completion of an inventory of the soapweed/yucca moth populations at the Onefour and Pinhorn sites by an independent biological consultant in 2011 for upcoming updated COSEWIC status reports for both species.
These activities have significantly contributed to meeting several of the objectives outlined in the initial recovery plan. Critical habitat for soapweed and yucca moths has been identified and has been protected through the placement of protective notations (PNTs) on both the Onefour and Pinhorn sites. The initiative of installing exclosures and individual range cages at the Pinhorn location in spring 2007 has effectively protected a portion of the soapweed population from ungulate herbivory. It is still important to recognize, however, that the fenced areas (i.e. exclosures) only represent a small portion of the overall population and herbivory continues to be a key threat, as evidenced by the high level of browsing noted outside of the exclosures (C. Linowski, pers. comm.; D. Hurlburt, pers. comm.). The yucca moth larvae translocation undertaken in 2008 involved the transfer of one soapweed stalk with 14 unripened fruit attached from the Etzikom museum population to the Pinhorn population. This effort, in conjunction with the fencing, has resulted in increased fruit set within the exclosures and an increased number of moth emergence holes being observed from year to year (C. Linowski, pers. comm.), suggesting an enhancement of the yucca moth population at the Pinhorn site. However, it still remains uncertain as to whether or not the reproductive rate is indicative of a viable yucca moth population at this site (D. Hurlburt, pers. comm.). It is hoped that the yucca moths will continue to reproduce within the exclosures, unhindered by herbivory, and eventually disperse out into the surrounding soapweed plants and establish a self-sustaining population (J. Nicholson, pers. comm.).
Monitoring of the Pinhorn soapweed/yucca moth population was conducted in the fall of 2009 2010, and 2011 by students and instructors from the Environmental Land Reclamation Program at Medicine Hat College, and in summer 2011 an additional inventory was completed by an independent biological consultant. Monitoring in 2009 and 2010 confirmed the presence of yucca moths, although still in limited numbers, as indicated by the few number of moth emergence holes observed. However, a much greater number of emergence holes were observed in 2010 compared to 2009, particularly in the soapweed plants contained within the largest exclosure. In addition to the increased number of emergence holes, there was also a significant increase in the number of new plants (clones), which may be attributed, at least somewhat, to the summer moisture (C. Linowski, pers. comm.). In 2010, many more yucca plants and inflorescence stalks were observed growing outside of the fenced areas and individual range cages than the previous year. Browsing of the flowering stalks was very apparent, as not a single pod was observed, demonstrating the necessity of the exclosures to protect the soapweed and yucca moths from herbivory (C. Linowski, pers. comm.).
Preliminary results from the inventory conducted in 2011 at the Pinhorn site revealed a high degree of fruit production among the flowering soapweed plants within the three fenced off areas and individual range cages, with the majority of plants producing fruit (D. Hurlburt, pers. comm.). Conversely, only one fruit was found outside of the exclosures and range cages, and it had been ripped off and was lying on the ground; a classic sign of herbivory. The degree of herbivory observed during the course of the inventory was noted as being very high (D. Hurlburt, pers. comm.). Another observation was a lack of enlarged pedicels being seen on the flowering stalks of plants situated on the slopes, suggestive of low moth density at the time of flowering. None of the soapweed plants on the slopes produced fruit, which may have more to do with a lack of yucca moths than herbivory by ungulates (D. Hurlburt, pers. comm.). No yucca moths were observed in the flowers, and there were no signs of late ovipositions. Another moth species that relies on soapweed for survival, Prodoxus quinquepunctellus (five-spotted bogus yucca moth), was present, although in much lower densities than at the Onefour site (D. Hurlburt, pers. comm.).
In 2011, flowering was very low at the Onefour site (< 1% of clones flowered), and fruiting success was significantly lower than in previous years (D. Hurlburt, pers. comm.). A lack of enlarged pedicels on flowering stalks, other than those that set fruit, suggests that it was not a very successful year for yucca moths. This may have been due to adverse environmental conditions, given the very wet spring and the fact that soapweed plants were still covered in snow in May (D. Hurlburt, pers. comm., I. Walker, pers. comm.). Although it would be considered a year of low reproduction, comparatively speaking, the soapweed/yucca moth population at Onefour is large and very well-established, and a “boom or bust” flowering/fruiting cycle has been noted over the years (D. Hurlburt, pers. comm.; I. Walker, pers. comm.).
The soapweed/yucca moth population at Onefour continues to be monitored on a regular basis, and all observations suggest that both species continue to persist at a sustainable level, in spite of the population’s highly variable flowering/fruiting cycle (i.e. periodic high flowering years followed by very low flowering years) (D. Hurlburt 2007; I. Walker, pers. comm.). Ongoing monitoring is still essential in order to detect any possible declines in the soapweed and/or yucca moth populations that could affect their long-term sustainability, particularly given that low flowering years tend to be more frequent than high flowering years (Hurlburt 2007).
Installation of interpretive signage in front of a living display of soapweed plants and yucca moths at the Etzikom Windmill Museum will enhance the public’s understanding and awareness of these two species at risk, and help promote their conservation. This site also allows those wishing to a see these species an alternate to visiting the natural sites and should help decrease traffic to these areas.
7.0 Recovery strategy
7.1 Biological and technical feasibility of recovery
Conservation of soapweed and yucca moths is possible and is compatible with a variety of land use activities. A cooperative management approach involving all stakeholders is the best approach to allow for the persistence of these species in Alberta. Soapweed and yucca moths continue to persist at the Onefour site, and maintaining sustainability of these populations at this site should be feasible with continued cooperation among stakeholders. The yucca moth population at the Pinhorn site could become viable if concerted management practices continue to be employed. The development of regulations under the Wildlife Act that protect Endangered and Threatened plants and invertebrates is needed to help ensure that losses of these species do not occur from horticultural, pharmaceutical, recreational, industrial, and agricultural activities.
7.2 Guiding principles
There are a number of soapweed plants in numerous towns and cities in southern Alberta. Most of these plants occur in household gardens, and some may be the result of transplants from native populations of soapweed in Alberta. The recovery strategies and actions recommended in this plan do not apply to these transplants.
The recovery and management of soapweed and yucca moths in Alberta will be guided by the following principles that were established in the initial recovery plan:
- Recovery and conservation of soapweed and yucca moths is possible and important.
- Loss of habitat for soapweed and yucca moths is unacceptable and preventable.
- A cooperative approach with land managers, landowners, industry, and other agencies is essential to the success of this plan in conserving soapweed and yucca moth populations in Alberta. This includes shared stewardship, compatible land use, and local commitment to management initiatives.
- Landowners and lessees will not be unduly affected by the costs associated with maintaining or enhancing habitat for soapweed and yucca moths.
- Knowledge gaps will be identified and will be communicated in the recovery plan.
- Management actions will use tools resulting in the most immediate benefits to soapweed and yucca moths and will be based on the best information available. Implementation will not be delayed because of a lack of specific supporting information.
- Recovery actions will embrace an ecosystem (holistic) approach to management.
- Recovery actions will focus on achievable initiatives and on those initiatives deemed most effective in conserving soapweed and yucca moths in Alberta.
- The recovery process will be guided by the concept of adaptive management, whereby specific actions are implemented, evaluated, and altered as necessary, to ultimately improve the outcome.
7.3 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.
7.4 Recovery objectives
The specific population and distribution objectives that will lead to the long-term conservation of soapweed and yucca moths in Alberta are:
- Maintain reduced herbivory levels by ungulates on soapweed populations, primarily at the Pinhorn site, over the life of the recovery plan.
- Maintain a reproducing population of yucca moths at the Pinhorn site over the life of the recovery plan.
- By 2022, attain a value for annual fruiting success for the Pinhorn population of soapweed of at least 5% of flowers, and maintain annual fruiting success for the soapweed population at Onefour of at least 7-10% of flowers as per Hurlburt 2004.
- Eliminate loss of habitat quantity or quality due to human-caused disturbances.
- Ensure no loss of soapweed plants due to harvesting for horticultural or medicinal purposes.
7.5 Recovery strategies
The goals and objectives of the Alberta Soapweed and Yucca Moth Recovery Plan 2012-2022 will be achieved through the implementation of six distinct strategies listed below, which will be pursued concurrently over the ten-year period.
7.5.1 Population conservation and management
In order to conserve and manage the population, the Soapweed/Yucca Moth Recovery Team recommends monitoring Alberta soapweed and yucca moth populations for population size, distribution, and reproductive success. As ungulates pose a threat to the Pinhorn population, management measures will continue to be explored.
7.5.2 Habitat conservation and management
Enhancing protection measures and means of limiting human disturbance in the area will be necessary to conserve habitat. This should be done in a cooperative fashion with land users.
7.5.3 Information and outreach
Measures will be taken to increase public awareness of soapweed and yucca moths and the need for, and importance, to conserve these species in Alberta.
Research will be focused on collecting information necessary for the conservation of soapweed and yucca moths. There will be agency support for researchers in their efforts to secure funding to undertake these investigations.
It is important to secure logistical, financial, and in-kind support to implement the recovery plan.
7.5.6 Plan Management and Administration
Throughout the life of the plan, members of the initial soapweed/yucca moth recovery team may be asked for advice on an as-needed basis. The plan will be updated at the end of term, or at any time during the term.
8.0 Action plan
8.1 Population conservation and management
- Government agencies, non-government organizations, or universities will conduct annual surveys of soapweed and yucca moth populations to monitor distribution, abundance, and trends of these species. When a sufficient amount of data has been collected, it should be used to undertake a population viability analysis for yucca moth.
- Government agencies, non-government organizations, or universities will establish a protocol for the translocation of yucca moth larvae and/or adults from the Onefour or Etzikom Museum site to the Pinhorn site and for monitoring the success of translocations. The number of individuals that are translocated each year will be dependent on the annual population size of soapweed (e.g., fruiting success) and yucca moths at the donor site and should not compromise the sustainability of these populations.
- When the translocation protocol is complete, and if it is deemed necessary, government agencies, non-government organizations, or universities will translocate yucca moth larvae and/or adults from the Onefour or alternate sites to the Pinhorn site following the protocol and will monitor moth numbers and soapweed fruiting success in subsequent years.
- AESRD will ensure appropriate management of native ungulates in WMU 102 where soapweed and yucca moths occur, including the use of population management techniques such as harvesting goals, ungulate repellents, or fencing, as required.
8.2 Habitat conservation and management
- Maps denoting critical habitat for soapweed and yucca moth will be maintained and used as the basis for permitting/mitigating land use.
- A variety of agencies and organizations, including AESRD, Agriculture and Agri-Food Canada, and universities, in coordination with land users, will cooperate to develop and deliver best management practices (BMPs) for livestock grazing within habitat supporting soapweed and yucca moths. BMPs will be updated/revised as new information becomes available.
- Government agencies or non-government conservation organizations will assist lessees and land managers to manage their land in a manner that sustains soapweed and yucca moths through the provision of various improvements.
- Agriculture and Agri-Food Canada (Onefour Research Substation) and Pinhorn Grazing Reserve, in association with AESRD and Alberta Tourism, Parks and Recreation, will develop access management plans to ensure that vehicles are not used within or immediately adjacent to habitat supporting soapweed and yucca moths.
- The boundaries of critical habitat will be reassessed periodically to account for population expansion over time.
8.3 Information and outreach
- AESRD will update the current fact sheet on soapweed and the yucca moth, as necessary. Fact sheets will be made available to the public, including lessees and land managers, on the Alberta Species at Risk website.
- Government agencies or non-government organizations will continue to work with the Etzikom Windmill Museum to promote conservation of soapweed and yucca moths to the public.
- AESRD will make the recovery plan available to the public and interested stakeholders on the Alberta Species at Risk website.
The following research is recommended, in order of priority, to provide information necessary to help conserve and maintain soapweed and yucca moths in Alberta.
- Researchers from government agencies, non-government organizations, or universities should monitor currently marked individual soapweed plants across seasons and years to understand the life history of soapweed and yucca moths, including the effects of variation in flowering levels, moth emergence, and fruit production on population dynamics of soapweed and yucca moths.
- Researchers from government agencies, non-government organizations, or universities should investigate the factors influencing larval survival of yucca moths to understand how larval survival impacts population dynamics and to help develop and refine a translocation protocol for this species.
- Researchers from government agencies, non-government organizations, or universities should investigate the direct and indirect effects of the moths, T. corruptrix and P. quinquepunctellus, on the soapweed-yucca moth mutualism.
- Government agencies, non-government organizations, and researchers, will periodically approach government, non-government, industry, land managers, leaseholders, universities, and private conservation organizations to participate in, or fund, recovery initiatives for soapweed and yucca moths.
8.6 Plan management and administration
- AESRD may convene previous members of the Alberta soapweed and yucca moth recovery team on as-needed basis.
- The Alberta Conservation Information Management System (ACIMS) centre staff, in cooperation with other agencies and researchers, will enter all soapweed and yucca moth data into the ACIMS database following each survey season.
- Research activities will be properly permitted and coordinated each year, in order to maximize benefits from research.
9.0 Timetable for implementation and schedule of costs
The following table provides a timeline for implementation and estimate of costs of activities identified as being important to the conservation of soapweed and yucca moths. It is anticipated that a variety of agencies will participate in the funding and implementation of these activities. Costs are not provided for activities that are part of the daily operations of the identified organizations.
|Plan Section||Action||Lead Agencya||2012-13||2013-14||2014-15||2015-16||2016-17||2017-18||2018-19||2019-20||2020-21||2021-22||Total|
|2||Best management practices||AESRD||-||5||-||-||-||-||-||-||-||-||5|
|4||Access management||AAFC, PGR||-||5||-||-||-||-||-||-||-||5||10|
|8.3||Information and Outreach||-||-||-||-||-||-||-||-||-||-||-||-|
|3||Publish and promote plan||AESRD||1||-||-||-||-||-||-||-||-||-||1|
|2||Moth larvae survival||-||15||15||15||-||-||-||-||-||-||-||45|
|3||Influence of other moths||-||15||15||15||-||-||-||-||-||-||-||45|
|1||Periodic team meetings||AESRD||1||-||-||-||1||-||-||-||-||1||3|
|4||Liaise with other recovery teams||AESRD||0.5||-||-||-||0.5||-||-||-||-||0.5||1.5|
a Lead agencies: AESRD - Alberta Environment and Sustainable Resource Development, ACIMS - Alberta Conservation Information Management System, AAFC - Agriculture and Agri-Food Canada, PGR - Pinhorn Grazing Reserve
10.0 Socio-economic considerations
The approximately 189 ha over which soapweed and yucca moths occur is a small enough area to limit potential socio-economic costs of implementation of the recovery plan. It is a guiding principle of the recovery plan that landowners and leaseholders should not be unduly affected by costs associated with implementation of the plan. Potential economic costs may include minor changes to grazing management that could involve decreased productivity or increased costs for livestock production. Potential costs associated with industrial development may include restrictions on resource extraction or increased costs for extraction or development resulting from mitigation measures. Other potential costs to recreational users and naturalists in the area may include reduced accessibility to view populations of soapweed and yucca moths and prohibition on their collection. The current management regime at Onefour has allowed the population to exist and expand, thus no significant changes to operations at Onefour should be anticipated.
There are several benefits that may be realized from implementation of the recovery plan. There is the potential for leaseholders to obtain improvements that increase the quality and productivity of their rangelands. The need to manage native ungulates in habitat supporting soapweed and yucca moths may increase recreational hunting opportunities in WMU 102. Soapweed and yucca moths are unique prairie species and there is considerable public interest in these species. Information and living displays of soapweed/yucca moth in local towns in Alberta (e.g., Etzikom Windmill Museum) may enhance tourism in these centres and reduce visits and disruption to natural sites.
11.0 Plan evaluation and amendment
The life of this plan is 10 years. Periodic reviews will be carried out to monitor the implementation of the plan and to determine the effectiveness of recovery actions. Recovery plans are considered “living” documents and can be amended during these reviews or at any time it is deemed necessary within the 10-year period. At the end of 10 years, an assessment will be done of any amendments that may be required prior to the plan being renewed for another 10 years. This may involve consultation with previous members of the recovery team or additional experts, management agencies, and stakeholders.
12.0 Literature cited
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Addicott, J. F., J. Bronstein, and F. Kjellberg. 1990. Evolution of mutualistic life-cycles: yucca moths and fig wasps. Pp 143-161 In Insect Life Cycles: Genetics, Evolution and Co-ordination (Gilbert, F. ed.). Springer, London. 258 pp.
Aker, C. L. and D. Udovic. 1981. Oviposition and pollination behaviour of the yucca moth, Tegeticula maculata (Lepidoptera: Prodoxidae), and its relation to the reproductive biology of Yucca whipplei (Agavaceae). Oecologia 49: 96-101.
Alberta Conservation Information Management System (ACIMS). 2005 natural regions and subregions of Alberta.
Alberta Sustainable Resource Development. 2002. Status of the yucca moth (Tegeticula yuccasella) in Alberta. Alberta Sustainable Resource Development, Fish and Wildlife Division, and Alberta Conservation Association, Wildlife Status Report No. 44, Edmonton, AB. 21 pp.
Baker, H. G. 1986. Yucca and yucca moths – a historical commentary. Annals of the Missouri Botanical Garden 73: 556-564.
COSEWIC. 2000. 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.
COSEWIC. 2002. Assessment and status report on the yucca moth Tegeticula yuccasella in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 24 pp.
COSEWIC. 2006. COSEWIC assessment and status report on the non-pollinating yucca moth Tegeticula corruptrix in Canada (PDF; 541 KB). Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 24 pp.
COSEWIC. 2006a. COSEWIC assessment and status report on the five-spotted bogus yucca moth Prodoxus quinquepunctellus in Canada (PDF; 491 KB). Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 31 pp.
Csotonyi, J. T. and D. Hurlburt. 2000. Update COSEWIC status report on the soapweed, Yucca glauca, in Canada, In COSEWIC assessment and update COSEWIC 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. United States National Museum Bulletin 255: 1-170.
Dodd, R. J. and Y. B. 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. Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada (PDF; 950 KB)
Fairbarns, M. 1985. COSEWIC status report on the soapweed, Yucca glauca, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 16 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, AB. 18 pp.
Hurlburt, D. 2004. Persistence of the moth-yucca mutualism at the northern edge of range. Ph. D. Thesis, Univ. of Alberta. Edmonton. 179 pp.
Hurlburt, 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. 42 pp.
Kershaw, L., J. Gould, D. Johnson, and J. Lancaster (Eds.). 2001. Rare Vascular Plants of Alberta. The University of Alberta Press and the Canadian Forest Service, Edmonton, Alberta. 484 pp.
Kingsolver, R. W. 1984. Population biology of a mutualistic association: Yucca glauca and Tegeticula yuccasella. Unpubl. Ph.D. Thesis, University of Kansas, Lawrence, KS. 130 pp.
Milner, B. J. 1977. Habitat of Yucca glauca in southern Alberta. Unpubl. M.Sc. Thesis, University of Alberta. 72 pp.
Pellmyr, O. 1999. Systematic revision of the Tegeticula yuccasella complex (Lepidoptera: Prodoxidae) north of Mexico. Systematic Entomology 24:243-271.
Riley, C. V. 1892. The yucca moth and yucca pollination. Missouri Botanical Garden Annual Report 3: 99-158.
Webber, J. M. 1953. Yuccas of the southwest. United States Department of Agriculture, Agriculture Monographs 17. 97 pp.
Wershler, C. and C. Wallis. 1986. Lost River significant features assessment. Alberta Forestry, Lands and Wildlife – AESRD, Edmonton, AB. 54 pp.
Hurlburt, D. Independent Biological Consultant. Annapolis Royal, NS.
Johnson, D. Professor of Environmental Science, Department of Geography, University of Lethbridge. Lethbridge, AB.
Linowski, C. Program Coordinator, Environmental Land Reclamation, Medicine Hat College. Medicine Hat, AB.
Nicholson, J., Senior Species at Risk Biologist, AESRD. Medicine Hat, AB.
Walker, I. Manager, AAFC Onefour Research Substation. Onefour, AB.
- Date Modified: