Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada - 2011

Species at Risk Act
Recovery Strategy Series
Adopted under Section 44 of SARA

Document Information


Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada - 2011

Cover of the publication: Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada – 2011.

Soapweed and Yucca Moth

Photo: Soapweed and Yucca Moth.

Recommended citation:

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.

Additional copies:

Additional copies can be downloaded from the Species at Risk (SAR) Public Registry.

Cover illustrations:

Soapweed - Geoffrey Holroyd © and Yucca Moth - Olaf Pellmyr ©

Également disponible en français sous le titre
« Programme de rétablissement du yucca glauque et de la teigne du yucca, au Canada »

© Her Majesty the Queen in Right of Canada, represented by the Minister of the Environment, 2011. All rights reserved.
ISBN 978-1-100-18540-8
Catalogue No. En3-4/104-2011E-PDF

Content (excluding the illustrations) may be used without permission, with appropriate credit to the source.

Recovery Strategy for the Soapweed (Yucca glauca) and Yucca Moth (Tegeticula yuccasella) in Canada - 2011

Under the Accord for the Protection of Species at Risk (1996), the federal, provincial, and territorial governments agreed to work together on legislation, programs, and policies to protect wildlife species at risk throughout Canada.

In the spirit of cooperation of the Accord, the Government of Alberta has given permission to the Government of Canada to adopt the Recovery Plan for the Soapweed and Yucca Moth in Alberta 2006-2011 (Appendix 1) as a recovery strategy under Section 44 of the Species at Risk Act (SARA).

Environment Canada has included an addition which completes the SARA requirements for this recovery strategy, and excludes the following sections of the Alberta Recovery Plan, which are not required by the Act: 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.

2011

This recovery strategy for the Soapweed and Yucca Moth in Canada consists of two parts:

  1. The federal addition to the Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011 prepared by Environment Canada; and
  2. The Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011 prepared by the Alberta Soapweed and Yucca Moth Recovery Team for Alberta Sustainable Resource Development found in Appendix 1.

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 within five years.

The Minister of the Environment is the competent minister for the recovery of the Soapweed and Yucca Moth. The SARA (section 37) requires the competent minister to prepare recovery strategies for listed extirpated, endangered, or threatened species. The 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 of recovery strategies (section 41).

Alberta Sustainable Resource Development led the development of the Recovery Plan for Soapweed and Yucca Moth in Alberta (2006-2011). Environment Canada led the development of the addition to this plan, to meet SARA requirements.

Success in the recovery of the Soapweed and Yucca Moth will depend 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 Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Soapweed and 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 Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this recovery strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

Soapweed has been listed as Threatened under SARA since June 2003. Yucca Moth has been listed as Endangered under SARA since January 2005. In February 2003, based on recommendations made by the Alberta Endangered Species Conservation Committee, the Minister of Sustainable Resource Development approved the listing of Soapweed and Yucca Moth as endangered under Alberta’s Wildlife Act;however only Soapweed is currently listed provincially.

Soapweed occurs in abundance throughout most of its range (COSEWIC 2000) and globally has been assessed as secure (G5; NatureServe 2009). In Canada, Soapweed has a conservation status of critically imperiled (N1) while in the United States it is considered secure (N5; NatureServe 2009). Soapweed is ranked as critically imperiled (S1) in Alberta, vulnerable (S3) in Iowa, and imperiled (S2) in Missouri, but has not been assessed in many of the states in which it occurs (NatureServe 2009).

Yucca Moth is known to utilize several different species of the genus Yucca and as such has a much wider North American distribution than Soapweed (COSEWIC 2002). The species has a rounded global status of apparently secure (G4), however the conservation status for this species has not been assessed in Canada or United States, or in the states in which it occurs (NatureServe 2009). In Alberta, the moth has received a ranking of critically imperiled (S1; NatureServe 2009). The percentage of global range in Canada has not been assessed but is most likely less that 1%.

The Alberta Soapweed and Yucca Moth Recovery Team have prepared the Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011 (thereof refer to Alberta’s 2006 Soapweed and Yucca Moth Recovery Plan) for Alberta Sustainable Resources; this document can be found in Appendix 1.

The following sections include key summary information and additional SARA recovery strategy requirements that have not been addressed in the provincial recovery plan.

Date of Assessment: May 2000

Common Name (population): Soapweed

Scientific Name: Yucca glauca

COSEWIC Status: Threatened

Reason for designation: Long-lived woody perennial found only in a few sites in southeastern Alberta where it reproduces mainly asexually, in large part due to very low numbers of a specialized moth on which it depends for the pollination of its flowers.

Canadian Occurrence: Alberta

COSEWIC Status History: Designated Special Concern in April 1985. Status re-examined and designated Threatened in May 2000.

Date of Assessment: May 2002

Common Name (population): Yucca Moth

Scientific Name: Tegeticula yuccasella

COSEWIC Status: Endangered

Reason for designation: Only one viable population of the moth persists in an extremely small and restricted area; another small population has been lost recently. The moth has an obligate mutualism relationship with its host plant, the soapweed, which is threatened by ungulate herbivory and loss of plants to human activities.

Canadian Occurrence: Alberta

COSEWIC Status History: Designated Endangered in May 2002.

There are only two naturally occurring[1] Soapweed and Yucca Moth populations in Canada; one population is found at Agriculture and Agri-Food Canada’s (AAFC) Onefour Research Station along the Lost River, Alberta, and the second population is found at Pinhorn Grazing Reserve near Manyberries, Alberta (Alberta Soapweed and Yucca Moth (ASYM) Recovery Team 2006). 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). However, effective habitat management practices, by means of fencing off three sections of the Soapweed population to reduce ungulate herbivory, resulted in approximately 10 Soapweed plants producing fruit in 2008 at the Pinhorn site (J. Nicholson pers. comm. 2009) indicating that the moths are still occurring and reproducing at the site, although it is not yet clear if these reproductive rates indicate a viable Yucca Moth population (D. Hurlburt pers. comm. 2009).

Numerous Soapweed plants, outside the AAFC Onefour Research Station and Pinhorn sites, occur in horticultural settings throughout southern Saskatchewan and Alberta; evidence of fruit and seed production at some locations suggests that Yucca Moths might also be present (ASYM Recovery Team 2006, D. Johnson pers. comm. 2008). The mode by which these extra-limital Soapweed plants are sexually reproducing is currently unknown. It is possible that some moths were transported as larvae 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 toremain in extended diapause in the soil for up to 30 years (Powell 2001). Another explanation to the observed soapweed fruit production is that the moths are dispersing from other occupied locations and expanding their range (D. Johnson pers. comm. 2008). Further research into Yucca Moth dispersal, persistence in horticultural settings, and the uncoupling of interactions among Soapweed and all other yucca moth species is required. Dan Johnson at University of Lethbridge is examining Yucca Moth dispersal potential and Soapweed fruit production in horticultural settings (D. Johnson pers. comm. 2008).

In 2006, the Alberta provincial Soapweed and Yucca Moth Recovery Team speculated that a third Soapweed population, located in Rockglen, Saskatchewan, might be native (ASYM Recovery Team 2006). Visits and consultations with local landowners have indicated that this population was introduced to the Rockglen area 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). At this time, Saskatchewan Environment considers all Soapweed plants found throughout Saskatchewan to be introduced and as such, Soapweed has a conservation status of "not applicable" (SNA) (Saskatchewan Conservation Data Center 2008).

Consequently, Soapweed and Yucca Moth populations found throughout Saskatchewan and Alberta in horticultural settings are considered accessory to meeting the goals and recovery objectives of this strategy. As more information becomes available, the status of Soapweed and Yucca Moths found in horticultural settings will be reassessed by Environment Canada as needed.

As stated in Alberta’s 2006 Recovery Plan, Soapweed and Yucca Moth have an obligate mutualistic relationship such that neither species can survive on a long-term basis and /or reproduce sexually without the other. Furthermore, the Canadian Soapweed and Yucca Moth populations are small, have a small area of occupancy, and are extremely isolated.

The greatest threats to the recovery of both species are in order of importance: ungulate and insect herbivory, plant collection for horticultural or medicinal uses, habitat destruction or alteration, uncoupling interactions among Soapweed and Yucca Moths, pollen limitation, and climatic conditions (ASYM Recovery Team 2006).

Under the Species at Risk Act (Section 40), the competent minister is required to determine whether the recovery of the listed species is technically and biologically feasible. Based on the following criteria outlined in the Species at Risk Act Policies (Government of Canada 2009) for recovering species at risk, the recovery of the Soapweed and Yucca Moth is considered biologically and technically 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 Soapweed and Yucca Moth populations in Canada. Although it is not yet clear if the Yucca Moth population at the Pinhorn Grazing Reserve is viable due to low moth reproductive rates, recovery efforts such as erecting exclosures to reduce ungulate herbivory on Soapweed as well as Yucca Moth translocation initiatives have the potential to increase moth reproductive rates.

2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

Yes. Suitable Soapweed and Yucca Moth habitat is presently available at both Pinhorn Grazing Reserve and AAFC Onefour Research Station in Alberta.

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 Yucca Moth recovery are ungulate and insect herbivory, habitat destruction or alteration, collection of Soapweed for horticultural purposes, and uncoupling interactions among Soapweed and Yucca Moth (ASYM Recovery Team 2006). These threats can be mitigated through beneficial management practices, protection of species and their habitat, and research into the biology and ecology of Soapweed and Yucca Moth and other species of yucca moths.

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 herbivory on Soapweed through building exclosures, Yucca Moth translocations, and the conservation of suitable habitat. These techniques are thought to be effective for Soapweed and Yucca Moth.

Environment Canada endorses the long-term recovery goal presented in section 7.3 and the specific population and distribution objectives presented in section 7.4 of the provincial recovery plan, and adopts them as the population and distribution objectives for the federal recovery strategy.

Population and distribution objectives

The long-term recovery goal of the recovery plan is to maintain the existing habitat and distribution of soapweed in Alberta and to enhance yucca moth population at the Pinhorn site. This will require the maintenance of naturally self-sustaining populations of soapweed and yucca moth at the AAFC Onefour Research Station site and an increase in the reproductive capacity at the Pinhorn site.

The specific population and distribution objectives that will lead to the long-term conservation of the soapweed and yucca moth in Alberta are:

  1. Reduce herbivory by ungulates on soapweed populations, primarily the Pinhorn population over the life of the recovery plan.
  2. Re-establish a reproducing population of yucca moths at the Pinhorn site by 2011.
  3. By 2011, 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 AAFC Onefour Research Station of at least 7-10% of flowers (as per Hurlburt 2004).
  4. Eliminate loss of habitat quantity or quality due to human-caused disturbances.
  5. Ensure no loss of soapweed plants due to harvesting for horticultural or medicinal purposes.

Recovery efforts for Soapweed and Yucca Moth that are underway or have been completed by Alberta Sustainable Resource Development’s Fish and Wildlife Division (FWD), Alberta Conservation Association (ACA), Agriculture and Agri-Food Canada, Environment Canada, University of Alberta, University of Calgary, or University of Lethbridge include:

Research and monitoring

Habitat Conservation and Management

Information and Outreach

Critical habitat is defined in the Species at Risk Act (Subsection 2(1)) 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”.

Identification of Soapweed and Yucca Moth critical habitat is based on best available information and was described in Alberta’s 2006 Soapweed and Yucca Moth Recovery Plan (Appendix 1). Critical habitat is identified as the area occupied by the two known naturally occurring populations as of 2006. Soapweed and Yucca Moth critical habitat consists of approximately 2 km² (182 ha at the AAFC Onefour Research Station site and the 2.65 ha at the Pinhorn site outlined by the polygonal maps on Figure 2 and 3 in the Alberta’s 2006 Soapweed and Yucca Moth Recovery Plan). The AAFC Onefour Research Station (under long-term lease from the province of Alberta, and managed by Agriculture and Agri-Food Canada), is treated as federal land under SARA while the Pinhorn site is on provincial public land.

Since 2006 when Soapweed and Yucca Moth critical habitat was described by the Recovery Team, several Soapweed plants have been found at the AAFC Onefour Research Station outside the boundaries of designated critical habitat (Hurlburt 2007). Although these were mature plants missed during the original inventory rather than being new recruits (Hurlburt 2007), the Alberta Soapweed and Yucca Moth Recovery Team acknowledges that Soapweed populations could expand their range in the near future and the established critical habitat boundaries may have to be revised accordingly (ASYM Recovery Team 2006). As such, the Recovery Team will continue monitoring the Soapweed and Yucca Moth populations, and when the provincial recovery plan is reviewed, the Recovery Team will reassess critical habitat boundaries to account for any range expansion (see Section 4.6, Schedule of studies of the Alberta’s 2006 Soapweed and Yucca Moth Recovery Plan). At that time, if new information about critical habitat boundaries becomes available, the Minister of the Environment may amend this recovery strategy accordingly or identify the additional critical habitat in an action plan.

Progress towards recovery for Soapweed and Yucca Moth will be measured against the following performance indicators:

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.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that plans 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 plan itself, but are also summarized below in this statement.

This recovery strategy will benefit biodiversity by promoting the recovery of the Soapweed and 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 2006-2011 for more information (Appendix 1).

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. Specifically, two other moth species, the Five-spotted Bogus Yucca Moth (Prodoxus quinquepunctellus) and the Non-pollinating Yucca Moth (Tegeticula corruptrix), require Soapweed flowers and fruit to complete their life cycle (COSEWIC 2006 a, b). Both species of yucca moths have been assessed by COSEWIC and were officially listed as Endangered under SARA in December 2007. Additionally, Soapweed is an obligate host for the Streckers Giant Skipper (Megathymus streckeri), a rare butterfly known to occur in Canada only at the AAFC Onefour Research Station (Hurlburt 2007). Efforts should be coordinated with the recovery teams working on all yucca moth species to ensure the most efficient use of resources, and to prevent duplication of effort and research. The creation of a multiple-species action plan may be beneficial for species that depend on Soapweed.

In addition to the yucca moth species, 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. Management and research activities would have a positive effect on federally-listed species including the Swift Fox (Vulpes velox, endangered), 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 (Phrynsoma hernandesi, endangered), Tiny Cryptanthe (Cryptantha minima, endangered), Small-flowered Sand Verbena (Tripterocalyx micranthus, endangered) and Smooth Goosefoot (Chenopodium subglabrum, threatened). Consequently, the promotion of Soapweed and Yucca Moth recovery will certainly assist the conservation of these endangered and rare species as well as a wide range of native plant species that occur in the area.

Environment Canada cooperated with the Government of Alberta and Agriculture and Agri-Foods Canada in adopting the Provincial recovery plan as a federal species at risk recovery strategy.

The individuals in Canada who are considered experts on the biology of the species were members of the Alberta recovery team. Additional opportunities for consultation were afforded through posting on the SAR Public Registry.

An action plan for the Soapweed and Yucca Moth may be adopted from the next update of the Province of Alberta’s Recovery Plan for these species. A federal action plan for these species will be completed by 2014.

Alberta Soapweed and Yucca Moth (ASYM) 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.

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.

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. 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. 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 2006 a. 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 2006 b. 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.

Government of Canada. 2009. Species at Risk Act Policies, Overarching Policy Framework [Draft]. Environment Canada, Ottawa. 38 pp.

Floate, K.D. 2002. Entomologists swarm to Onefour in 2001 (PDF; 183 Kb). Lethbridge Research Center, Agriculture and Agri-Food Canada. Accessed: 24 September 2008.

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.

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

Hurlburt, D. D. 2005. Monitoring protocol for Soapweed (Yucca glauca) and Yucca Moths (Tegeticula yuccasella) in Alberta (Draft). Submitted to the Alberta Soapweed and Yucca Moth Recovery Team. 21 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.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available at: . (Accessed: August 20, 2009).

Perry, J.C. 2001. Indirect mutualism: how ants affect the yucca-yucca moth relationship. B.Sc. thesis, University of Alberta, Edmonton, Alberta.

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

Saskatchewan Conservation Data Center (PDF ; 410 Kb). 2008. Saskatchewan Ministry of Environment, Saskatchewan Conservation Data Center.
(Accessed December 12, 2008).

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

Personal Communications

Bill Richards, Tourism, Parks & Recreation, Parks Division, Edmonton, Alberta.

Darcy Henderson, Grassland Ecologist, Environment Canada, Prairie and Northern Wildlife Research Centre, Regina, Saskatchewan.

Dan Johnson, Professor of Environmental Science, Canada Research Chair in Sustainable Grassland Ecosystems, University of Lethbridge, Lethbridge, Alberta.

Dean Hystad, Rangeland Agrologist, Sustainable Resources Development, Prairies Area, Medicine Hat, Alberta.

Donna Hurlburt, Species at Risk Biologist (Consultant) and Technical Advisor - Alberta Soapweed and Yucca Moth Recovery Team, Annapolis Royal, Nova Scotia.

Erl Svendsen, Biodiversity Analyst, Range and Biodiversity Division, Prairie Farm Administration, Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan.

Joel Nicholson, Senior Species at Risk Biologist, Alberta Fish and Wildlife, Medicine Hat, Alberta.

Tara Sample, Previously: Coordinator, Rare Plant Rescue and PlantWatch, Nature Saskatchewan, Regina, Saskatchewan.

Will Stryker, Director of Pinhorn Grazing Reserve and Member of Alberta Soapweed and Yucca Moth Recovery Team, Manyberries, Alberta.

Alberta Species at Risk Recovery Plan No. 11

Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2011

Prepared by:

The Alberta Soapweed and Yucca Moth Recovery Team

Joel Nicholson (Team Leader and Chair), Alberta Fish and Wildlife Division
Joyce Gould, Alberta Parks and Protected Areas Division
Joanne Golden, Alberta Native Plant Council
Terry Hood, Alberta Public Lands and Forests Division
Dan Johnson, Agriculture and Agri-Food Canada and University of Lethbridge
Kelley Kissner, Alberta Fish and Wildlife Division
Will Stryker, Pinhorn Grazing Association

Recovery Team Technical Advisor

Dr. Donna Hurlburt

July 2006

Publication No.: I/247
ISBN: 0-7785-4791-4 (Printed Edition)
ISBN: 0-7785-4792-2 (On-line Edition)
ISSN: 1702-4897 (Printed Edition)
ISSNz: 1702-4900 (On-line Edition)

Cover photos:
Yucca Moths on Soapweed Plant – Dan L. Johnson
Soapweed Habitat – Joyce Gould
Soapweed in Bloom – Joyce Gould

For copies of this report, contact:

Information Centre – Publications
Alberta Sustainable Resource Development
Main Floor, Great West Life Building
9920 – 108 Street
Edmonton, Alberta, Canada T5K 2M4
Telephone: (780) 422-2079

OR

Visit the Alberta Species at Risk Program web site at:

http://www.srd.gov.ab.ca/fw/speciesatrisk/

This publication may be cited as:

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


List of Figures


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 imperilled 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.

Alberta species at risk recovery plans are prepared under the supervision of the Fish and Wildlife Division, Alberta Sustainable Resource Development. These recovery plans are prepared by recovery teams 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 includes 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.

These plans are provided by the recovery team as advice to the Minister responsible for fish and wildlife management (the Minister) and to all Albertans. Alberta’s Endangered Species Conservation Committee reviews draft recovery plans, and provides recommendations to the Minister. In addition, an opportunity for review by the public is 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. These plans are “living” documents and are revised as conditions change or circumstances warrant. Each approved recovery plan undergoes an annual 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.

The Alberta Soapweed and Yucca Moth Recovery Team would like to thank Donna Hurlburt (University of Alberta) for providing invaluable technical information and advice to the team during the preparation of this plan.

Support for the development of this recovery plan was provided by all member organizations and individuals and the Species at Risk Program of Alberta Sustainable Resource Development.

Soapweed (Yucca glauca Nuttall), 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 Riley) 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.

In February 2003, the Minister of Sustainable Resource Development approved the listing of soapweed and yucca moth as Endangered in Alberta. These designations were based on the Alberta population of soapweed occurring at only two sites and occurring over a small area. In addition, both sites are isolated from soapweed populations in the United States (United States). Yucca moths appear to be near extirpation in one of the two Alberta populations (Pinhorn population) and both populations are isolated from moth populations in the United States. A number of factors, including ungulate herbivory, collection of soapweed for horticultural or medicinal uses, habitat destruction or alteration, uncoupling of interactions among soapweed and yucca moths, pollen limitation, insect herbivory, and intense winds may threaten the persistence of these species in Alberta. The goals of the recovery plan are to: (1) maintain the existing habitat and distribution of soapweed and yucca moth in Alberta; (2) maintain naturally self-sustaining populations of soapweed and yucca moth at the Onefour site; (3) increase the reproductive capacity of soapweed and yucca moth populations at the Pinhorn site.

The specific strategies used to attain these goals are: (1) conservation and management of soapweed and yucca moths populations and management of native ungulate populations to reduce losses due to herbivory; (2) conservation and management of habitat in order to maintain the quality and quantity of habitat used by soapweed and yucca moth; (3) provision of information and educational materials to the public and stakeholders to promote the conservation requirements of soapweed and yucca moth; (4) research to elucidate aspects of the life history of soapweed and yucca moths to better understand how to conserve these species; (5) acquisition of resources needed to implement the recovery plan, and (6) 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 moth, combined with stakeholder cooperation and commitment, will allow for the long-term persistence of soapweed and yucca moths in Alberta.

In February 2003, the Minister of Sustainable Resource Development approved the listing of soapweed (Yucca glauca Nuttall) and yucca moth (Tegeticula yuccasella Riley) as Endangered under the Wildlife Act in Alberta on the recommendation of the Alberta Endangered Species Conservation Committee (ESCC). 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. The yucca moth appears to be declining in one of the two Alberta populations (Pinhorn population) and both populations are isolated from moth populations in the United States (Hurlburt 2001). Recommendations from the ESCC, and approved by the Minister, specified that a recovery plan should be developed in order to set goals, objectives, strategies and management actions necessary to guide the management of these two species during the next five years. The ESCC also recommended that management of these species should focus on the identification and conservation of existing populations. The initial conservation action statement for soapweed/yucca moth further stated that pending development and implementation of the plan, 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 is both practical and appropriate.

In May 2000 and 2002, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated soapweed and 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). Until recently, native populations of soapweed and yucca moth were known only to occur in Alberta. However, one native population of soapweed, and also possibly of yucca moths, may occur at one site in Saskatchewan (D. Hurlburt, pers. comm.). However this is still under investigation and debate.

At the direction of the Minister of 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 is to facilitate, monitor and evaluate the conservation and recovery of these species in Alberta. It provides expert advice to the Minister (or his delegate) on all matters relating to the management of soapweed and yucca moth in Alberta, through the development of a provincial recovery plan. The recovery team typically does not implement recovery actions directly, although team members and the organizations they represent generally participate in the planned recovery actions. The team will encourage and facilitate the involvement of all interested parties in the recovery of soapweed and yucca moth in Alberta, whenever possible, and will periodically report on the progress of the recovery program.

Membership of the recovery team attempts to include the best representation of parties likely to affect or to be affected by recovery actions and consists of the following member organizations: Alberta Sustainable Resource Development (Fish and Wildlife Division and Public Lands and Forests Division), Alberta Community Development (Parks and Protected Areas Division--Alberta Natural Heritage Information Centre), Agriculture and Agri-Food Canada, University of Lethbridge, Alberta Native Plant Council, and the Pinhorn Grazing Association.

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 seedbank that cannot ensure the persistence of the species (Alberta Sustainable Resource Development 2002).

Yucca moths are small night-flying moths. Forewings are generally white with a wingspan of 18 to 28 mm (Pellmyr 1999). Hindwings 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 (Alberta Sustainable Resource Development 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 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 significant numbers 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 1982). 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 pupate, up to 50% die in the cocoon (D. Hurlburt, unpubl. data).

Soapweed is restricted to the Dry Mixed Grass Subregion (ANHIC 2002). 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.).

Soapweed and yucca moths occur naturally at two locations in southeastern Alberta. One location is near Onefour along the Lost River drainage within the boundaries of the Agriculture and Agri-Food Canada Onefour Research Station. The second 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 Community Development (Parks and Protected Areas 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.). Additionally, approximately 50 non-reproducing plants occur in Fox Valley, Saskatchewan (Fairbarns 1985, Hurlburt 2001). Six clones also occur near Rockglen, Saskatchewan (D. Henderson, pers. obs., D. Hurlburt, pers. comm.). In 2003, one flowering stalk (inflorescence) was observed at this site indicating that flowering had occurred in the past. Enlarged pedicels observed on the stalk suggest that flowers may have been pollinated and thus, that yucca moths may have been present in the past.

Soapweed occurs along a 2 km stretch of slope at the Onefour location and along a 200 m stretch of slope at the Pinhorn site (Hurlburt 2001, Alberta Sustainable Resource Development 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). Fruit has not been produced at the Pinhorn site in recent years (at least since 1997 or earlier), suggesting that this population is only reproducing asexually (Hurlburt 2004).

Population trends of soapweed are difficult to determine. A total of 59,450 plants were counted in 1977 (Milner 1977). The large decrease between this count and the 1998 census (29,577 plants) appears to be due to differences in survey techniques rather than a decline in population size (Csotonyi and Hurlburt 2000).

Figure 1. The distribution of soapweed and yucca moths in Alberta. Site 1 is the Onefour population and site 2 is the Pinhorn Population. Map modified from Hurlburt (2001).

Figure 1 contains a reference map of Alberta and southern Saskatchewan and an enlarged area focussing on the southern part of the shared border between the two provinces.  In the enlarged map, two locations of Soapweed and Yucca Moth are shown, both in the extreme southeast part of Alberta.

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 moths 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.

The greatest threat to soapweed and yucca moths is the loss of their partner species. Several natural and human-caused factors 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. Several of the natural limiting factors, such as insect herbivory or wind, are unlikely to be mitigated or managed by actions outlined in this recovery plan.

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, particularly when cattle are present during the flowering season. 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). Although cattle are present at the Pinhorn site, there is no evidence of cattle browsing on soapweed possibly because native ungulates graze plants early during flowering.

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.

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 consent from the Minister of Community Development, given this site’s 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).

There is also considerable public interest in these species. Both sites are accessible by road and are often visited daily during the summer (Hurlburt 2001, COSEWIC 2002). Plants and moths may be threatened by off-road traffic through direct trampling of plants (Hurlburt 2001). 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.). 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.

Alberta populations of soapweed show little or no fruit production in some years (< 1% of flowers bear fruit), low pollination, and low emergence of moth larvae from fruit (Hurlburt 2001). These characteristics are atypical of the species compared to 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 no recent fruit production at the Pinhorn may suggest that this population is also pollen limited.

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).

Another moth, (Tegeticula corruptrix), lays its eggs in soapweed fruit but does not pollinate the plant. These non-pollinating moths may impact soapweed and yucca moths by depositing enough eggs that many seeds are consumed by the larvae. In Alberta, T. corruptrix larvae can consume up to 40% of seeds (Hurlburt 2001). Another moth, Prodoxus quinquepunctellus (‘five spotted bogus yucca moth’), lays its eggs in the flowering stalks of soapweed but does not appear to impact the plant (D. Hurlburt, pers. comm.).

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. Hulburt (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).

Critical habitat is a legal designation under the SARA. Recovery Teams define critical habitat in the recovery plan. The emphasis is on defining habitat that is “necessary for survival or recovery of a listed wildlife species” (Species at Risk Act 2002 s 2). In defining critical habitat, recovery teams must also specify activities that may result in destruction of critical habitat. These parameters afford protections for critical habitat as destruction of critical habitat is illegal on lands where the SARA applies.

Soapweed is restricted to the Dry Mixed Grass Subregion (ANHIC 2002). This is a region characterized by extremes with a low annual precipitation, usually between 260 mm - 280 mm (Hurlburt 2001). 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).

Soapweed exists naturally in two locations in Alberta; the Onefour and Pinhorn locations (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 accomodate population expansion. 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 3 below). The boundaries will be reassessed in a period of five years to allow for more critical habitat designation if the population expands.

Because yucca moth has 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.

Figure 2. Range of soapweed at the Onefour Site.

Figure 2 is a topographical map showing the range of Soapweed at the Onefour site, which includes a total area of 182 hectares.

Figure 3. Range of soapweed at the Pinhorn Site.

Figure 3 is a topographical map showing the range of Soapweed at the Pinhorn site, which includes a total area of 2.65 hectares.

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.

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).

Both soapweed/yucca moth sites in Canada have some protections in place from threats to the species. The Onefour site falls within a Heritage Rangeland Natural Area, which is afforded the some protections under Wilderness Areas, Ecological Reserves and Natural Areas 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, however, oil and gas activity could pose a threat if the site does not have protective notations (PNT) placed on it. A PNT will ensure that industrial users are not allowed to develop within the boundary of critical habitat. Additionally, Alberta Public Lands and Forests and Fish and Wildlife must be contacted prior to development to ask for recommendations and conditions about access and development to be submitted. The recovery team recommends PNTs be placed on the critical habitat designated for this species. As part of experimental treatments for moth translocation, parts of the Pinhorn site may be fenced, thus eliminating the possibility of vehicle access. It is recommended that an access management plan for the site is developed. See section 8.0 for further clarification of recovery actions for protecting critical habitat.

At this time, no further studies are needed to identify critical habitat for soapweed and yucca moth. The entire known populations of both species in Alberta are located within critical habitat areas outlined above. However, at the time of recovery plan review in 2011, it would be worthwhile to determine whether the boundaries of soapweed and yucca moth have expanded and if the boundaries of critical habitat also need to be expanded to support a larger population.

Translocation is one management option for increasing fruit production at the Pinhorn site (see Section 8.0). However, it is unclear how a translocation should proceed and 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. Finally, research is also needed to determine how other moth species (T. corruptrix and P. quinquepunctellus) that exploit soapweed influence the soapweed-yucca moth mutualism. This information will be particularly important if upcoming national status evaluations of these moth species result in federal listing of these species. If so, recovery actions for soapweed and yucca moths will need to consider the requirements to conserve these other moth species.

Recent conservation and recovery efforts for soapweed and yucca moth include a survey of the Pinhorn population in 2004 to determine the size of the population, evidence of fruit production and the extent of herbivory occurring at the site (Nicholson, J. pers. comm.). The results of this survey are expected to be published in 2006.

Alberta Fish and Wildlife has initiated a project to erect interpretive signage at the Etzikom museum near a living display of soapweed plants to promote conservation of endangered species and increase awareness of soapweed and yuccamoth and other endangered species in Alberta.

Work is being completed by the University of Lethbridge to complete a translocation protocol for yucca moths to the Pinhorn site, and fencing options for experimental treatments are being considered.

Initiation of other recovery and conservation efforts is pending completion and approval of this recovery plan.

It is the belief of this recovery team that conservation of soapweed and yucca moth is possible and is compatible with a variety of land use activities. It is also a belief of the recovery team that 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 most immediate threat to the Alberta populations of soapweed and yucca moth is extirpation of either of these species at the Pinhorn site. The most recent survey of yucca moths at the Pinhorn site (2002) located no yucca moth. One female moth was observed in 1999. These surveys show there has been no recent sexual reproduction of soapweed, or likely of yucca moths, at this site at least since 1997. It is also likely that there are no or few remaining dormant moth larvae in the soil at this site, since larvae generally remain viable in a dormant stage for one to four years. Recovery of soapweed and yucca moths at the Pinhorn site should be possible if attempts to reintroduce yucca moths and to manage grazing of soapweed by native ungulates are successful. The development of regulations under the Wildlife Act that protect Endangered and Threatened plants and invertebrates will also help ensure that losses of these species do not occur from horticultural, pharmaceutical, recreational, industrial and agricultural activities.

There are also several limiting factors affecting the recovery and conservation of soapweed and yucca moths that are beyond the control of the Alberta Soapweed and Yucca Moth Recovery Team and this recovery plan. These include the uncoupling of interactions between soapweed and yucca moths, exploitation by non-pollinators, pollen limitation, insect herbivory, and the effects of wind.

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:

The long-term goal of the recovery plan is to maintain the existing habitat and distribution of soapweed in Alberta and to enhance 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.

The specific population and distribution objectives that will lead to the long-term conservation of the soapweed and yucca moth in Alberta are:

  1. Reduce herbivory by ungulates on soapweed populations, primarily the Pinhorn population over the life of the recovery plan.
  2. Re-establish a reproducing population of yucca moths at the Pinhorn site by 2011.
  3. By 2011, 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.
  4. Eliminate loss of habitat quantity or quality due to human-caused disturbances.
  5. Ensure no loss of soapweed plants due to harvesting for horticultural or medicinal purposes.

The Alberta Soapweed and Yucca Moth Recovery Plan will serve for an initial period of five years (2006-2011), and consists of the following strategies that will be pursued concurrently:

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 be explored.

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.

Measures will be taken to increase public awareness and understanding of the need for and requirements to conserve soapweed and yucca moths in Alberta.

Research will be focussed on providing 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.

Agencies will work to review provincial government policy or legislation necessary to ensure the long-term conservation and maintenance of soapweed and yucca moths in Alberta.

Throughout the life of the plan, the Soapweed/Yucca Moth Recovery Team will convene to ensure that actions are being completed and are contributing to the recovery of the species.

  1. 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. Data should be used to undertake a population viability analysis for yucca moth before year 3.
  2. Government agencies, non-government organizations or universities will establish a protocol and program for translocation of yucca moth larvae and/or adults from the Onefour 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 sizes of soapweed (e.g., fruiting success) and yucca moths at the Onefour site and should not compromise the sustainability of these populations. The Soapweed and Yucca Moth Recovery Team recommends that the feasibility analysis and protocol be developed in year 2.
  3. When the translocation protocol is complete, government agencies, non-government organizations or universities will translocate yucca moth larvae and/or adults from the Onefour site to the Pinhorn sites following the translocation protocol and will monitor moth numbers and soapweed fruiting success in subsequent years. The Soapweed and Yucca Moth Recovery Team recommends that translocations be conducted in years 3 to 5.
  4. Alberta Fish and Wildlife Division will ensure appropriate management of native ungulates in WMU 102 where soapweed and yucca moths occur, including ungulate population management (e.g., harvesting goals) and ungulate repellents and fencing, as required.
  1. Alberta Fish and Wildlife Division, with the assistance of other government agencies, or non-government organizations will develop and deliver maps denoting critical habitat for soapweed and yucca moths this area to resource managers (e.g., Alberta Fish and Wildlife Division, Alberta Community Development, Alberta Public Lands and Forests Division, Alberta Energy). These maps should be used as the basis for permitting/mitigating land use. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 2.
  2. Alberta Fish and Wildlife Division will make application to the Alberta Public Lands and Forests Division to place protective notations, consultative notations, or other protective designations on all quarter sections with naturally occurring populations of soapweed and/or yucca moths. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 1 and be updated as necessary.
  3. A variety of agencies and organizations, including Alberta Fish and Wildlife Division, Alberta Public Lands and Forests Division, Agriculture and Agri-Food Canada, and universities, in coordination with land users, will cooperate to develop and deliver best management practices (BMP) for livestock grazing within habitat supporting soapweed and yucca moths. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 2 and will be updated in years 3 to 5 as new information becomes available.
  4. When necessary, 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. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in years 1 to 5.
  5. Agriculture and Agri-Food Canada (Onefour Research Station) and Pinhorn Grazing Reserve, in association with Alberta Fish and Wildlife Division, Alberta Public Lands and Forests Division, and Alberta Community Development, will develop access management plans to ensure that vehicles are not used within or immediately adjacent to habitat supporting soapweed and yucca moths. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 2.
  6. The recovery team will reconvene to reassess the boundaries of critical habitat to allow for population expansion over time. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 5.
  1. Alberta Fish and Wildlife Division will update the current fact sheet on soapweed and 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 and in hardcopy through the Alberta Sustainable Resource Development Information Centre.
  2. Government agencies or non-government organizations will develop displays at the Onefour site and at the Etzikom Windmill Museum to promote conservation of soapweed and yucca moth to the public. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 2.
  3. Alberta Fish and Wildlife Division will make the recovery plan available to the public and interested stakeholders on the Alberta Species at Risk Program web site and in hardcopy through the Alberta Sustainable Resource Development Information Centre. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in year 1.

The Alberta Soapweed and Yucca Moth Recovery Team recommends the following research, in order of priority, that will provide information necessary to help conserve and maintain soapweed and yucca moths in Alberta.

  1. Researchers from government agencies, non-government organizations, or universities will monitor currently marked individual soapweed plants across seasons and years to understand 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. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in years 2 to 5.
  2. Researchers from government agencies, non-government organizations, or universities will 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. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in years 3 to 5.

Researchers from government agencies, non-government organizations, or universities will investigate the direct and indirect effects of the moths, T. corruptrix and P. quinquepunctellus, on the soapweed-yucca moth mutualism. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in years 3 to 5.

  1. Government agencies, non-government organizations, and researchers, will 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. The Soapweed and Yucca Moth Recovery Team recommends that this initiative be undertaken in years 1 to 5.
  1. The Alberta Soapweed and Yucca Moth Recovery Team supports the development of regulations under the Wildlife Act for the protection of Endangered and Threatened plants and invertebrates, and their habitat. The Recovery Team has expressed a desire to review the draft regulations after their development to ensure they adequately protect soapweed and yucca moths and their habitat while allowing for compatible landuse activities, such as livestock grazing.
  1. Alberta Fish and Wildlife Division will convene the Alberta Soapweed and Yucca Moth Recovery Team a minimum of once annually. At these meetings, the team will review progress on implementation of the plan, review the effectiveness of recovery actions, and will develop new recovery actions, as required. The Chair of the recovery team will provide an annual report to the Director of Wildlife Management that details progress on implementation of the plan and any recommended changes to the plan.
  2. The Alberta Natural Heritage Information Centre (ANHIC), in cooperation with other agencies and researchers, will enter all accumulated soapweed and yucca moth data into the ANHIC database following each survey season.
  3. The Chair of the Alberta Soapweed and Yucca Moth Recovery Team, in association with Alberta Fish and Wildlife Division (Medicine Hat office) and Alberta Community Development, will ensure that all research activities are properly permitted and coordinated each year, in order to maximize benefits from research and to keep the recovery team informed of ongoing research.
  4. The Chair of the Alberta Soapweed and Yucca Moth Recovery Team will liaise with other recovery teams to ensure that recovery actions for soapweed and yucca moths complement, where possible, the recovery of any other provincially or federally listed species.

The following table provides a timeline for implementation and estimate of costs of activities identified by the Alberta Soapweed and Yucca Moth Recovery Team 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. Costs associated with team members’ expenses to attend recovery team meetings are not included, but represent valued and necessary contributions associated with implementation of the recovery plan.


Recovery Plan Section
Activity Lead Agency Cost (thousands/year) Total
2006-07 2007-08 2008-09 2009-10 2010-11
7.1 Population Management
1 Surveys Various 15 15 15 15 15 75
2 Translocation protocol FWD 5 5
3 Translocations FWD 5 5 5 5 20
4 Ungulate management FW 5 5 5 5 20
15 30 25 25 25 120
7.2 Habitat Management
1 Maps FWD 2 2
2 Protective notations FWD, PL 0
3 Best mgt practices FWD, PL 2 2 2 2 8
4 Habitat improvements FWD 2 2 2 2 8
5 Access management AAFC, PGR 5 5
0 11 4 4 4 23
7.3 Education / Information
1 Fact sheets FWD 1 1 2
2 Displays FWD 10 10
3 Publish and promote plan FWD 0.5 0.5
1.5 10 0 0 1 12.5
7.4 Research
1 Life history FWD 20 20 20 20 80
2 Moth larvae survival FWD 20 20 20 60
3 Influence of other moths FWD 20 20 20 60
20 60 60 60 200
7.5 Resource Acquisition
1 Secure funding FWD 2 2 2 2 2 10
2 2 2 2 2 10
7.6 Legislation
1 Review legislation FWD 0
0 0 0 0 0 0
7.7 Plan Management
1 Annual meeting/report FWD 1 1 1 1 1 5
2 Database management ANHIC 0
3 Research coordination FWD 0
4 Liason with other RT’s FWD 0.5 0.5 0.5 0.5 0.5 2.5
1.5 1.5 1.5 1.5 1.5 7.5
TOTAL 24.5 75 92.5 92.5 93.5 373

Lead agencies: Alberta Fish and Wildlife Division (FWD), Alberta Public Lands and Forests Division (PL), Alberta Natural Heritage Information Centre (ANHIC), Agriculture and Agri-food Canada (AAFC), Pinhorn Grazing Reserve (PGR), Recovery Team (RT).

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 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 siginificant 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.

The life of this plan is 5 years. The Alberta Soapweed and Yucca Moth Recovery Team will conduct an annual review of the plan. The purpose of these annual reviews is to monitor the implementation of the plan and to determine the effectiveness of recovery actions. The Chair of the recovery team will provide an annual report to the Director of Wildlife Management that details progress on implementation of the plan. Recovery plans are considered “living” documents and can be amended during these reviews. At the end of 5 years, the recovery team will meet again to determine whether any other amendments are required, prior to the plan being renewed for another five years. The team may determine that the existing recovery plan is suitable, in need of minor edits, or in need of a major revision.

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.

Addicott, J. F. and A. J. Tyre. 1995. Cheating in an obligate mutualism: how often do yucca moths benefit yuccas? Oikos 72: 382-394.

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 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.

ANHIC. 2002. Dry Mixedgrass Subregion. Alberta. Natural Heritage Information Centre. URL: http://www.cd.gov.ab.ca/preserving/parks/anhic/drymixedgrass.asp.

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. 2003. COSEWIC Assessment Results, November 2003. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 44 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.

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.

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.

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. 1982. The yucca moth and Yucca pollination. Missouri Botanical Garden Annual Report 3: 99-158.

Species at Risk Act. 2002. (Canada) s 2.

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 – Public Lands Division, Edmonton, AB. 54 pp.

Personal Communication Contacts

Hurlburt, D., Ph. D. Student, University of Alberta. Edmonton, Alberta

Nicholson, J., Endangered Species Biologist, Alberta Fish and Wildlife Division. Medicine Hat, Alberta.

Johnson, D., Professor of Environmental Science, Department of Geography, University of Lethbridge, Lethbridge, Alberta.

List of Titles in the Alberta Species at Risk Recovery Plan Series (as of July 2006)

No. 1 Maintenance and Recovery Plan for Western Blue Flag (Iris missouriensis) in Canada. (2002)

No. 2 Alberta Piping Plover Recovery Plan 2002-2004. (2002)

No. 3 Alberta Peregrine Falcon Recovery Plan 2004-2010. (2005)

No. 4 Alberta Woodland Caribou Recovery Plan 2004/05-2013/14. (2005)

No. 5. Recovery Plan for Ord’s Kangaroo Rat in Alberta. (2005)

No. 6 Recovery Plan for Burrowing Owl in Alberta. (2005)

No. 7 Alberta Northern Leopard Frog Recovery Plan 2005-2010. (2005)

No. 8 Alberta Greater Sage-Grouse Recovery Plan. (2005)

No. 9 Maintenance and Recovery Plan for Western Spiderwort in Alberta 2005-2010. (2005)

No. 10. Alberta Piping Plover Recovery Plan 2005-2010. (2006)

No. 11. Recovery Plan for Soapweed and Yucca Moth in Alberta 2006-2010.


1 Naturally occurring populations 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.

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