Red Crossbill, percna subspecies
This recovery strategy for percna in Canada sets goals and objectives that will respond to knowledge gaps and contribute to the knowledge base of percna in Newfoundland to guide appropriate actions to facilitate recovery.
4.1 Feasibility of Species Recovery
Recovery of percna is considered to be technically and biologically feasible at this time. However, the threats that led to the species’ decline, along with current threats, limiting factors, and assessment of existence, must be better understood before the feasibility of recovery can be reconfirmed.
The success of Red Crossbill recovery in Newfoundland will depend primarily on how the threats to the species are mitigated and the maintenance of viable habitat within insular Newfoundland. Red Crossbills were observed breeding in Newfoundland in 2005 and again in 2006; although it was not known if these individuals were the percna subspecies, it does indicate that Red Crossbill breeding activity is still ongoing within Newfoundland. Forest inventory maps of Newfoundland indicate that there are a minimum of 1.6 million hectares of softwood-dominated forest of cone-bearing age on the island of Newfoundland (see Appendix 2). A properly designed survey effort will offer insight into the status of the population and provide information on the limiting factors that need to be mitigated to promote the recovery of the percna subspecies of Red Crossbill.
4.2 Recommended Approach/Scale for Recovery
Recovery actions for the Red Crossbill, percna subspecies, may occur in the context of a multispecies or ecosystem approach encompassing other species at risk in the boreal forest of insular Newfoundland in the future, if similar threats are found to apply to these other species or if their critical habitats overlap. At this time, however, recovery efforts for the percna will follow a single-species approach.
4.3 Recovery Goal and Objectives
The limited information available for this species makes the establishment of quantitative goals and objectives difficult. The vision for the Red Crossbill, percna subspecies, is to restore the species to a self-sustaining population level whereby it is able to withstand stochastic events. To achieve this vision, three goals will need to be met:
- Prevent extirpation of the percna subspecies from the island of Newfoundland.
- Reduce more complex and root causes of threats to the species, such that the population size can be enhanced to a self-sustaining level.
- Manage sufficient Red Crossbill, percna subspecies, habitat to support a self-sustaining population.
Objectives for 2006–2010 that will contribute to meeting these goals are to:
- Develop the tools needed to confirm the presence of percna in Newfoundland by developing appropriate identification criteria based on surveys, genetic analysis/sampling, vocalizations, and comparative analysis of morphological information.
- Determine the distribution and abundance of Red Crossbills in Newfoundland by applying these tools and using targeted survey and monitoring programs.
- Initiate studies of the movements of Red Crossbills across the landscape, including to and from mainland Canada. This could potentially include immigration/emigration of additional subspecies that may be present.
- Determine habitat associations, and begin to assess life history parameters.
- Begin assessment of potential threats and limiting factors.
- Reconfirm technical and biological feasibility of recovery by assessing the following:
a. Are individuals capable of reproduction currently available to improve the population growth rate or population abundance?
b. Is sufficient suitable habitat available to support the species, or could it be made available through habitat management or restoration?
c. Can significant threats to the species or its habitat be avoided or mitigated through recovery actions?
d. Do the necessary recovery techniques exist, and are they demonstrated to be effective?
- Determine specific population and habitat goals.
- Identify critical habitat as defined by the Species at Risk Act and critical and recovery habitat as defined by the Newfoundland and Labrador Endangered Species Act.
- Begin development of procedures to mitigate threats.
- Develop and implement stewardship and education programs, and promote public awareness of Red Crossbills.
4.4 Approaches to Meet Recovery Objectives
The following recovery approaches are premised largely on three points:
1. The presence of the percna subspecies as reported by COSEWIC (2004) is still unconfirmed at this time.
2. Red Crossbill populations have drastically declined since the mid-1900s, and reasons for the decline are unclear (although major threats associated with food and habitat availability and/or quality have been suggested).
3. Red Crossbills change their locations based on cone availability, but very little is understood about their distribution and movements in Newfoundland.
Recovery approaches are summarized in Table 1.
4.4.1 Presence of percna Subspecies
The percna subspecies is a large-billed Red Crossbill with a unique call. Call matching combined with bill measurements is considered the most accurate method to distinguish if a Red Crossbill is the percna subspecies in the field (note: capture and measurement protocols are not yet developed for percna). Few audio recordings of percna exist, but these can be used to match call with bill size to assist with identification. Additionally, responses of the percna subspecies to playback of other Red Crossbill types need to be determined. Further effort should be made to collect recordings of Red Crossbills in Newfoundland for comparative analysis. In addition, genetic analysis is necessary to determine the degree of gene flow between Red Crossbills on the island of Newfoundland as well as between populations on Newfoundland and the mainland.
4.4.2 Determine Survey Areas
Red Crossbills have been observed across the entire island of Newfoundland, and this distribution is probably based on locally irruptive behaviour, with movements largely reflecting cone crops in an area (COSEWIC 2004). Large-billed Red Crossbills (like percna) tend to be sedentary (Marquiss and Rae 2002), and it is believed that percna nests only within insular Newfoundland (COSEWIC 2004). Observations of Red Crossbills within the last 10 years have been concentrated on the east coast of Newfoundland, likely a reflection of the distribution of the birding community. The historical range of percna is believed to have included the entire island (COSEWIC 2004).
When determining survey areas, it will be important to target cone-producing conifer habitat. The six conifer tree species native to Newfoundland (black spruce, white spruce, tamarack, red pine, eastern white pine, balsam fir) all begin cone production by 15–25 years of age, with good cone-bearing years usually beginning around age 40 (Burns and Honkala 1990; B. English, pers. comm. 2005). Primary focus areas will likely shift with time, but can be predicted using standard forest inventory maps (i.e., conifer species distribution and stand age-class maps). As Red Crossbill declines in Newfoundland may be linked to loss and fragmentation of native pine, sites with concentrations of sexually mature pine are considered priority target areas, despite Benkman (1993c) having discounted the link between disappearing pine and the decline of percna.
A spatially explicit predictive model of potential percna habitat in Newfoundland should be created using standard land cover inventories and geographic information system (GIS) technology. Such a model could be useful in developing the survey program.
4.4.3 Develop Survey Protocols to Initiate Long-term Monitoring
Survey protocols need to be targeted to confirm the presence of the percna subspecies and to determine the distribution, movements, habitats, and population status of Red Crossbills in Newfoundland.
4.4.4 Habitat Enhancement
If it is determined that there is a relationship between pine and Red Crossbill habitat requirements, forest management activities can be directed towards the increase of pine across the landscape. This would include the protection of existing pine, the planting of pine, and the encouragement of natural pine regeneration. Within a mixed conifer plantation, seasonal changes in crossbill diet that may have been related to seed weight, cone toughness, and seedfall phenology of predominant conifers have been documented, indicating the importance of mixed conifer habitat (Marquiss and Rae 1994; Wren 2001).
4.4.5 Promote Public Awareness
Aside from the birding community and those directly involved with species at risk and/or boreal forest management, it is unlikely that many people are even aware that the percna subspecies exists or that it is at risk. Public support for percna conservation should be enhanced, especially among people most likely to encounter the subspecies (e.g., birders, foresters, hikers). This support is necessary not only to encourage compliance with protective measures, but also to engage the public in stewardship. Additionally, public awareness may increase occurrence data, as the species is sometimes observed at feeders.
4.5 Potential Management Impacts on Other Species
Management strategies must be developed such that they do not entail significant adverse effects on other species, particularly native ones. Although specific habitat associations are not yet known for percna, any strategies that increase the extent and/or quality of Red Crossbill habitat (which at this time is considered to be a mosaic of cone-producing conifers) will likely be beneficial for other species with similar habitat requirements.
Management of non-native, interspecific competitors and predators in Red Crossbill habitat may be deemed necessary for recovery only if food competition and/or nest predation are confirmed as limiting factors. Such management efforts must ensure that other species, particularly native ones, are not negatively impacted. Indirect management through environmental modifications to make areas unattractive or unproductive to food competitors will not likely be considered an option, as such a strategy would be expected to negatively impact crossbills and/or other species.
Regeneration of pine is also suggested as a possible method of recovery, pending further studies. Given that red and eastern white pine are native to the island, regeneration of these species may be beneficial to a host of other native species. Modifying current habitat may in turn negatively impact species that rely on predominantly black spruce and balsam fir stands. However, this would likely be at a very small scale.
4.6 Actions Already Completed or Under Way
In an effort to encourage greater awareness of Red Crossbills among a widely distributed population of stakeholders and to initiate the steps towards developing a large-scale, island-wide monitoring program, Red Crossbill brochures and sighting cards were developed and distributed in May 2005 by the Canadian Wildlife Service in partnership with Bird Studies Canada. These products were developed to increase awareness and volunteer participation, in addition to centralizing the sightings from volunteers from forestry companies, Parks Canada, and the bird-watching community with Bird Studies Canada and Environment Canada. Project FeederWatch in Newfoundland was targeted for this project, since participants are already participating in a preexisting bird monitoring project. Because of their nomadic/irruptive nature, Red Crossbills do not show up at feeders every year; in fact, FeederWatchers may go for many years without seeing any Red Crossbills. However, FeederWatchers are ideally situated for reporting this species, and information from these sightings will assist in tracking local irruptions and new percna records to the centralized database for use in mapping percna distribution and habitat in Newfoundland. Forest inventory crews of the Newfoundland and Labrador Department of Natural Resources have also been involved in the collection of bird data for a number of years and will be particularly on the lookout for percna. Copies of the brochure have been sent to Department of Natural Resources District offices.
The mapping of habitat use areas has also been initiated. Red Crossbill sighting information is being compiled and known nesting areas are being mapped to determine forest cover type and any other available information on habitat. These maps will lay the foundation for future survey and habitat assessment efforts.
Table 1. Summary of recovery approachesa
|Recovery approach||Priority||Objective No.||Specific steps||Effect|
- Obtain audio recordings of percna, other Red Crossbill types, and other boreal bird species
- Match bill size to call in the field
- Conduct genetic analysis
|Identifies feasibility of recovery|
|Determine survey areas.||Necessary||1|
- Map areas of conifer trees by species and age class
- Determine cone productivity across the island by species
- Map areas of Red Crossbill sightings and nesting records
- Communicate with local birding community
- Assess relationship between pine and percna
|Guides recovery actions|
|Develop survey methods and protocols.||Necessary||2 and 3|
- Develop survey techniques and protocols as outlined in the literature
- Obtain and make copies of audio recordings of percna
- Evaluate incorporation of established survey techniques (such as Christmas Bird Counts and Breeding Bird Survey)
|Guides recovery actions|
|Survey to assess presence of Red Crossbills, including a focus on potential nesting habitat.||Urgent||2 and 3||- Count adults, juveniles, and nests||Enhances knowledge base, identifies knowledge gaps, determines feasibility of recovery.|
|Identify critical habitat.||Necessary||4|
- Identify breeding, foraging, and roosting habitat
- Identify nesting habitat for productivity assessment
- Design models to identify and designate critical habitat
|Guides habitat protection|
|Monitor population size, distribution, movement, and productivity.||Urgent||All|
- Continue previous steps
- Establish permanent and mobile survey routes
- Begin banding study
- When nests are located, measure productivity
|Enhances knowledge base, identifies knowledge gaps, determines feasibility of recovery; continued monitoring evaluates success of recovery efforts|
|Protecting habitat.||Necessary||All||- Encourage forest management policies that maintain forest stand type and age structure until there is a better understanding of specific habitat requirements||Maintains potential for food availability|
|Identifying threats and limiting factors.||Urgent||All||- Conduct research in Red Crossbill habitat to assess potential threats described in section 2 and Appendix 1||Identifies and guides recovery actions|
|Monitoring threats, and mitigating negative impacts.||Urgent||All|
- Monitor severity, extent, frequency, and timing of recognized threats
- Develop action plans to determine mitigation techniques
- Promote stewardship
- Develop educational material
|Motivates and coordinates recovery actions|
a Each strategy addresses all objectives except as noted. Priorities are defined as follows: Urgent = top priority action, without which population will decline; Necessary = needed to evaluate and guide recovery actions; Beneficial = beneficial if urgent actions are already under way.
4.7 Implementation Schedule
The schedule of actions for the Red Crossbill, percna subspecies, recovery program is outlined in Table 2.
Table 2. Schedule of actions for the Red Crossbill, percna subspecies, recovery programa
|Determine survey areas|
|Identification of percna|
|Develop survey protocols|
|Surveys to assess presence; monitor population size, distribution, and movements||CWS|
|Protocols for morphological, vocalization, banding, and genetic studies|
|Assess population viability|
|NLWD||Develop PVA model||Data collection – ongoing|
|Identify critical habitat|
|Identify and monitor limiting factors and threats|
a BW – bird-watching community; CWS – Canadian Wildlife Service; For Ind – forest industries;MUN – Memorial University of Newfoundland; NLDNR – Newfoundland and Labrador Department of Natural Resources; NLWD – Newfoundland and Labrador Wildlife Division; PVA – population viability analysis
- Date Modified: