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Recovery Strategy for the Black-footed Ferret (Mustela nigripes) in Canada

2. Recovery

2.1 Recovery feasibility

The recovery of black-footed ferrets in Canada is considered feasible because the species meets the four necessary conditions (Environment Canada 2005) described below:

  1. Are individuals capable of reproduction currently available to improve the population growth rate or population abundance? Answer: Yes

    A very successful black-footed ferret conservation breeding program currently exists based on founder stock collected in the mid 1980s from the last remaining population of wild black-footed ferrets in Meeteetse, Wyoming. This conservation breeding program balances the goal of maximizing genetic diversity with the goal of maximizing kit production (IUCN/SSC Conservation Breeding Specialist Group (CBSG) 2004). The breeding program is spread across seven facilities in the U.S. and Canada to prevent genetic loss due to a catastrophic event. Since 1987, approximately 5800 black-footed ferrets have been born in captivity (Marinari pers. comm.). This includes a Canadian black-footed ferret breeding program at the Toronto Zoo which extends back to 1992 and produces ferrets for the Association of Zoos and Aquariums (AZA) Black-footed Ferret Species Survival Plan (SSP) and reintroduction efforts in the U.S. and Mexico.

    Although the allocation of ferrets must be balanced across recovery efforts throughout North America, BFFRIT strongly supports the recovery of ferrets in Canada and will strive to ensure sufficient ferrets are available (Lockhart pers. comm.).

    The black-footed ferret conservation breeding program is based on only seven founder animals, raising some concerns about the genetic viability of the population. However, the expression of inbreeding depression is highly species and population specific. The North American regional black-footed ferret studbook database is currently being modified to allow a systematic evaluation of the relationship between inbreeding coefficients and population viability rates (Miller et al. 2005). Despite a moderate level of inbreeding (the average inbreeding coefficient approaches F=0.12), there is no anecdotal evidence suggesting the occurrence of inbreeding depression in the captive population (Miller et al. 2005).

    Ferret recovery efforts in the U.S. show that captive bred ferrets do successfully reproduce in the wild (CBSG 2004). Nearly every captive bred female breeds in the first breeding season after release and their litter sizes are similar to those of more experienced wild ferrets (Livieri pers. comm.). Despite the loss of genetic diversity associated with the small founder population and more than a decade of subsequent captive breeding, neither female fecundity nor juvenile survival appears affected (Wisely et al. 2002). Several U.S. ferret reintroductions that utilized captive bred ferrets are now self-sustaining including Conata Basin and Cheyenne River Sioux Tribe, South Dakota; Shirley Basin, Wyoming and Aubrey Valley, Arizona (Livieri pers. comm.).


  2. Is sufficient suitable habitat available to support the species, or could it be made available through habitat management or restoration? Answer: Yes

    The primary limiting factor to black-footed ferret recovery in the U.S. is lack of sufficient habitat of adequate size and configuration. Influences that negatively affect the size of prairie dog colonies and the density of prairie dogs within colonies reduce the suitability of black-footed ferret habitat (Rodger et al. 2004). Habitat fragmentation can render remaining prairie dog colonies unsuitable for black-footed ferrets if the distance between the colonies becomes too great to create sufficient ferret habitat across the greater prairie dog complex or if ferret movement between colonies is impeded. As prairie dog colonies become smaller or more widely separated, successful ferret movement between colonies is less likely and the total ferret population that can be supported is reduced (Bevers et al. 1997). That being said, relatively limited amounts of black-footed ferret habitat do not always hinder recovery efforts. Experiences in the U.S. show that reintroduction efforts on smaller prairie dog colonies can be successful. For example, 36 ferrets were released at Heck Table, a subcomplex within Conata Basin, South Dakota measuring less than 1000 ha. No additional supplementation of ferrets occurred after the initial release in 1999. Yearly monitoring shows this population has been self-sustaining for seven years (Livieri pers. comm.).

    Population viability analysis (PVA) modeling of black-footed ferrets in the Conata Basin, South Dakota shows that approximately 4,047 ha of prairie dog colonies connected by a maximum distance of 1.5 km are required to sustain a ferret population with greater than 90 percent probability of persistence over 100 years (CBSG 2004). Though PVA modeling provides a useful tool, many unknowns around ferret behaviour and demographics in Canada make it difficult to accurately predict the number of ferrets the habitat will support before ferrets are released. For example, the 'island' arrangement of Canadian prairie dog colonies may be beneficial in supporting higher numbers of ferrets than the larger blocks of more uniform habitat. Biggins et al. (2006b) suggest that 'island' arrangements of prairie dog colonies with high enough density to support just one female and her litter reduce the limiting effect of female territoriality and, thereby, support more ferrets overall than large blocks of uniform habitat. Five of nine ferret litters in Mellette County, South Dakota were raised on colonies less than 16 ha in size (Hillman et al. 1979). Ferrets may also utilize alternative prey sources more extensively as the historical range map in Canada suggests. Post-release monitoring of ferrets will provide the best assessment of habitat requirements. Should strategic increases in prairie dog colony numbers or size be required to meet the recovery goal, effective techniques exist to expand the prairie dog colonies in a directed manner (Bly-Honness et al. 2004; Hof et al. 2002; Johnson & Collinge 2004; Merriman et al. 2004; Milne-Laux & Sweitzer 2006).

    Currently, approximately 1000 ha of black-tailed prairie dogs exist in Grasslands National Park and the surrounding area. Though it is difficult to predict, preliminary estimates suggest that current prairie dog colonies within Grasslands National Park may support approximately 30 ferrets, a population size that would be highly vulnerable to extinction and would likely require on-going supplementation (Miller et al. 2005). Based on knowledge gained through black-footed ferret recovery efforts in the U.S. and Mexico, the long-term target of a carrying capacity of 50 ferrets is suggested for Canada (Miller et al. 2005).

    The limited habitat available in Canada should not preclude reintroductions of ferrets in Canada. However, intensive monitoring of ferrets, prairie dogs, and other species at risk will be necessary to ensure that subsequent recovery actions can proceed adaptively with detailed information regarding successes, challenges and effects on other species.



  3. Can significant threats to the species or its habitat be avoided or mitigated through recovery actions? Answer: Yes

    Significant threats to black-footed ferrets have been identified as: sylvatic plague, natural diseases, Great-Horned Owl predation, poisoning of Richardson's ground squirrels and black-tailed prairie dogs, climate change and reduced genetic diversity. All threats, except sylvatic plague, can be effectively addressed with the actions outlined below.

    Mitigations for Threat 1 - Sylvatic plague

    There are currently no effective prevention or control strategies for sylvatic plague, although insecticide dusting of prairie dog burrow systems can aid in halting the spread of plague in the early stages of an outbreak (Hoogland et al. 2004; Karhu & Anderson 2000; Seery et al. 2003). Managing prairie dog colonies in such a way that some colonies remain isolated from the larger complexes may offer some protection in the event of a plague outbreak.

    Although sylvatic plague is prevalent in the ecosystem and has the ability to dramatically reduce both prairie dog numbers and black-footed ferret viability if a disease outbreak occurs, the potential impacts of this disease should not deter the reintroduction of ferrets to Canada. A sylvatic plague outbreak has not been documented in Canadian prairie dogs and may not occur despite its presence in the environment. For example, coyotes consistently test positive for plague in some ferret reintroduction sites in the U.S., such as Aubrey Valley, Arizona, but a plague outbreak has not occurred (Livieri pers. comm.). In addition, the previously accepted belief that the ferret's main prey, prairie dogs, could not survive in the presence of even low levels of plague may not hold true. Recent evidence suggests that plague can exist in prairie dog colonies without causing widespread prairie dog mortality (Hanson et al. 2007).

    American ferret recovery efforts also yield differing outcomes for plague outbreaks post-ferret release. In many cases, a plague outbreak results in the demise of the ferret population and the discontinuation of the site for further reintroductions. However, in the case of Shirley Basin, Wyoming, the effects of a plague outbreak appear to have been overcome. Two hundred thirty-eight ferrets were released at Shirley Basin between 1991 and 1993. A plague outbreak subsequently occurred and it was assumed that no ferrets survived. The site was not managed or monitored until 1997 when five ferrets were found; this number increased to 12 in 2000 and to 196 in 2006 (Livieri pers. comm.). Although plague is a serious threat and the risk to the population is unknown, recovery efforts should not be stalled due to lack of knowledge. Even a failed reintroduction attempt will increase knowledge and contribute to North American ferret conservation.

    Mitigation for Threat 2 - Natural diseases

    Natural disease threats can be effectively addressed through proper quarantine and vaccination protocols. Black-footed ferret reintroductions in the U.S. have shown that canine distemper virus can be addressed by vaccinating all released and wild-born ferrets with Purevax Ferret® (Merial, Athens, Georgia, 30601, U.S.A). A vaccine booster should be administered. A single vaccination with Imrab 3® (Merial, Athens, Georgia, 30601, U.S.A.) provides ferrets with sufficient protection against rabies infection. Working with local residents to ensure that all domestic dogs maintain a current rabies and canine distemper virus vaccination status will also reduce this threat. All other natural diseases present only low level threats.

    Mitigation for Threat 3 - Predation

    Pre-release conditioning of captive-born black-footed ferrets significantly reduces mortality (Biggins et al. 1999). Therefore, releasing only pre-conditioned captive-born or wild translocated ferrets will minimize the predation threat. Should an individual predator, such as a Great-Horned Owl, begin to specialize on preying upon ferrets to the extent that an entire ferret release group is threatened, that particular individual will be removed from the ferret reintroduction area.

    Mitigation for Threats 4 through 7

    In Canada, existing legislation that prohibits the unlicensed killing of black-tailed prairie dogs provides a legal tool to protect ferret habitat. Black-footed ferrets are listed as 'Extirpated' under the Species at Risk Act and The Wildlife Act of Saskatchewan, making killing, harming, harassing or capturing black-footed ferrets, as well as destroying their residence or critical habitat illegal (Government of Canada 2002; Government of Saskatchewan 1998, 1981). The remaining threats can be effectively avoided or mitigated through:

    • supplementation of the ferret population at key points to reduce extinction risks from genetic loss,
    • education, research and monitoring to support conservation and management decisions,
    • implementation and enforcement of existing legislation (Species at Risk Act, Canada National Parks Act, The Wildlife Act of Saskatchewan and Saskatchewan Wildlife Regulations), and
    • landowner agreements and inter-agency cooperation.


  4. Do the necessary recovery techniques exist and are they demonstrated to be effective? Answer: Yes

    The first releases of black-footed ferrets occurred in the U.S. in 1991. Since then, the techniques required to recover black-footed ferrets have been developed and demonstrated to be effective. These include, but are not limited to: captive breeding, pre-release conditioning, release and wild translocation techniques, monitoring and census methodology, and disease management protocols. Canada will benefit greatly from the BFFRIT's many years of experience in reintroducing ferrets.

2.2 Recovery goal

The recovery goal is to establish a wild population of black-footed ferrets in Canada that has at least an 80 percent probability of persisting for 20 years (i.e. less than 20 percent probability of extinction in 20 years). This level of viability is a significant milestone because it is commonly used as a quantitative indicator of endangerment (Committee on the Status of Endangered Wildlife in Canada (COSEWIC) 2004; International Union for Conservation of Nature (IUCN) 2006b).

2.3 Recovery objectives

These objectives are for the 5-year time period following the final posting of this document on the SAR Registry:

  1. Develop and maintain broad sector support for black-footed ferret recovery and conservation, with emphasis on key stakeholders.
  2. Reintroduce black-footed ferrets in Canada.
  3. Ensure that other species at risk populations are not adversely affected by black-footed ferret recovery.
  4. Determine the factors affecting carrying capacity of ferret habitat in Canada in order to establish short-term and long-term population goals.
  5. Integrate black-footed ferret recovery efforts into larger conservation planning and actions for co-existing prairie species.

An accurate understanding of the maximum number of ferrets for which there is theoretically enough habitat (i.e. carrying capacity) is a prerequisite for estimating the viability of the black-footed ferret population. Unfortunately, current estimates of carrying capacity for ferrets in Canada are imprecise, although expert opinion suggests that additional habitat will be required. Studies of released ferrets and the characteristics and dynamics of the prairie dog population will be necessary to improve estimates of carrying capacity and consequently, the amount of habitat required to achieve the recovery goal.

Once the current carrying capacity for ferrets has been estimated, a strategic long-term plan for developing sufficient habitat to achieve the recovery goal can be developed. This may encompass lands outside Grasslands National Park and potentially beyond the current distribution of prairie dog colonies. Preliminary population models based on expert opinion indicate that achieving the recovery goal may necessitate an increase of 500 to1100 ha of prairie dog colonies in order to achieve a carrying capacity of at least 40 ferrets, assuming female ferrets each require 55 to 80 ha of habitat (Miller et al. 2005; Rodger et al. 2004). This model will be refined using the results of future research projects. The engagement of stakeholders and conservation partners is necessary to assist in the development and implementation of a program to increase the number and size of prairie dog colonies through voluntary habitat stewardship and land securement programs. If additional habitat is required, this will be addressed in conjunction with the development of revised recovery strategy/action planning documents that includes cooperation and consultation with the relevant parties.

Black-footed ferret populations will require monitoring as the population may need periodic supplementation to prevent extirpation. Infrequent supplementation may be required even after achieving the recovery goal. The recovery of a Canadian population of black-footed ferrets will contribute to the North American conservation of ferrets by re-establishing a wild-functioning ferret population at the northern edge of the species' distribution. This population would be primarily affected by natural factors, thus providing opportunities for natural selection to occur.

Stakeholder considerations

Focus group surveys of regional stakeholders showed that there is broad support for black-footed ferret reintroduction and recovery (Bowman 2006). However, landowners and the Rural Municipality of Val Marie have expressed significant concerns about the implications of a ferret reintroduction on the management of black-tailed prairie dog populations and Richardson's ground squirrels. Most of the concern is due to the uncertainty of how these issues will be handled. These concerns have been satisfactorily addressed in the black-footed ferret action plan and black-tailed prairie dog management plan.

2.4 Approaches recommended to meet recovery objectives

Table 2. Summary of recovery objectives and strategies for recovery (Critical = without which the population will decline; Necessary = needed to evaluate and guide recovery; Beneficial = beneficial to recovery)
ObjectivePriorityBroad StrategyThreat addressedSpecific Steps
1. Develop and maintain broad sector support for black-footed ferret recovery and conservation, with emphasis on key stakeholdersNecessaryConsultation, education, visitor experience and community outreachAll threats
  • Assess the initial attitude of potentially affected stakeholders, key agencies and the local community towards black-footed ferret recovery and measure the attitude changes over time.
  • Finalize and implement a communication plan to effectively inform/involve local, regional and national audiences about black-footed ferret recovery and conservation as well as prairie dog management. As part of this communication strategy develop visitor experience opportunities for park visitors, volunteers, and regional stakeholders to assist research and monitoring activities and receive educational opportunities from ferret and prairie dog management specialists.
  • Develop a stewardship program to reduce risk of accidental ferret mortality due to poisoning and to encourage landowner acceptance of prairie dogs and their habitat.
  • Work with local residents to ensure that domestic dogs obtain a current rabies and canine distemper virus vaccination status to reduce the threat of disease to the ferrets.
  • When appropriate, hire persons from local communities to assist in research, monitoring or education activities.
  • Provide timely feedback to landowners and potentially affected stakeholders on black-footed ferret related research.
2. Release black-footed ferrets in CanadaCriticalResearch; PlanningAll threats
  • Complete an action plan and submit a ferret allocation request to the U.S. Black-footed Ferret Implementation Team to obtain ferrets for release.
  • Release black-footed ferrets on well-connected prairie dog colonies along the Frenchman River, Saskatchewan. The number of ferrets allocated for release in Canada will determine the number and location (possibility of release outside of the park) of reintroduction sites. The first ferret releases will take place in the fall of 2009.
  • Monitor black-footed ferret population size, demographics and genetics.
  • Support the US Fish & Wildlife Service and the AZA Black-footed Ferret Species Recovery Plan
3. Ensure that other species of at risk populations are not adversely affected by black-footed ferret recoveryNecessaryResearch; Monitoring 
  • Conduct pre and post-ferret reintroduction surveys of species at risk populations occurring in the ferret release area.
  • Mitigate adverse affects of ferret recovery on other species at risk in conjunction with relevant recovery teams.
4. Determine the factors affecting carrying capacity of ferret habitat in Canada in order to establish short-term and long-term population goalsNecessaryResearchSylvatic plague; Natural diseases; Climate change.
  • Map prairie dog colonies at least every 2 years.
  • Monitor density of prairie dogs on a sub-sample of colonies each year.
  • Estimate the number of ferrets that the current habitat can support.
  • Quantify demographic rates for prairie dogs and how these are affected by seasonal weather patterns (such as drought) and predation.
  • Improve population viability analysis as new information becomes available.
  • Evaluate the extent of predation on the ferrets and methods to manage such predation if necessary.
  • Evaluate ferret prey selection and habitat selection in Canada.
5. Integrate black-footed ferret recovery efforts into larger conservation planning and actions for co-existing prairie speciesNecessaryCommunication and collaborationAll threats
  • Integrate black-footed ferret recovery into more comprehensive prairie conservation/species planning initiatives and collaborate with other Canadian recovery teams to explore landscape scale conservation initiatives that may benefit all species concerned.
  • Integrate ferret recovery into prairie conservation education programming.
  • Hold a meeting of prairie SAR recovery teams annually to coordinate recovery approaches and action planning.
  • Work in partnership with black-footed ferret recovery committees in the U.S. and Mexico to coordinate black-footed ferret recovery on a continental basis.

2.5 Performance measures

An adaptive management approach should be used whereby new information feeds back into the recovery process on a regular basis in order to take advantage of new tools, knowledge, challenges and opportunities. A five-year evaluation of our progress in achieving the recovery objectives will be based on the performance measures listed below, using 2008 as the benchmark year.

  • The Management Plan for Black-tailed Prairie Dogs in Canada has been written, and broad sector support, especially in key stakeholders, for black-footed ferret recovery has been developed and maintained.
  • An approved black-footed ferret action plan that successfully addresses stakeholder concerns has been completed.
  • Black-footed ferrets have been reintroduced to Canada.
  • The number of ferrets that can currently be supported by existing habitat has been estimated.
  • The short and long-term recovery goals have been developed and refined.
  • Populations of prairie dogs and Burrowing Owls on prairie dog colonies have been monitored within the ferret release region and any necessary mitigations implemented.

2.6 Critical habitat

2.6.1 Identification of the black-footed ferrets' critical habitat

An initial step in achieving the recovery goal will be to establish a population of black-footed ferrets in the prairie dog colonies along the Frenchman River in Saskatchewan. The critical habitat needed to support this phase of ferret recovery in Canada is defined by the boundaries of the prairie dog colonies in Canada as of 2007 (Figure 2), but excludes all existing roads and their ditches within these boundaries. This includes prairie dog colonies within the current boundary of Grasslands National Park, the Masefield Community Pasture (Agri-Environment Services Branch, Agriculture and Agri-Food Canada), the Dixon Community Pasture (Province of Saskatchewan), on provincially leased land and privately deeded land. The colonies that occur on lands managed by two landowners, which are on a combination of private and provincially leased lands, are within the boundary of the proposed Grasslands National Park. As part of the 1988 Parks Canada - Province of Saskatchewan Grasslands National Park establishment agreement, section 12.1 specifies that "Saskatchewan agrees to manage the proposed national park in a manner that recognizes the need to maintain the lands in their existing natural state for park purposes prior to the transfer of administration and control of such lands to Canada." This implies that those lands and prairie dog colonies within the proposed park boundary are afforded some protection. The management of the black-tailed prairie dog colonies is specified in a Species at Risk Act compliant black-tailed prairie dog management plan.

Ferret populations will be monitored for five years post-release and the number of ferrets that the existing habitat can support will be estimated, as well as their usage of additional habitats. This information will be used to determine whether existing critical habitat can support the recovery goal. If additional habitat is required, this will be addressed in conjunction with the development of revised recovery strategy/action planning documents that includes cooperation and consultation with the relevant parties.


Figure 2. Critical habitat for the black-footed ferret in Canada

Critical habitat for the black-footed ferret in Canada (see long description below).

Livieri, pers. comm.

Description of Figure 2

Figure 2 is a map that displays the critical habitat for the black-footed ferret in Canada. It also displays the Frenchman River, Roads, the Grassland National Park, Dixon Community Pasture, Masefield Community Pasture and the location of privately managed ranches.

Because the identification of additional habitat may be needed to achieve the long-term ferret recovery goal, several of the recovery actions outlined in Table 3 are prerequisite activities to determine the location of potential habitat. Parks Canada may also conduct research on the techniques to expand existing prairie dog colonies or establish new prairie dog colonies.


2.6.2 Examples of activities likely to result in destruction of critical habitat

Critical habitat for black-footed ferrets is destroyed when ferrets can no longer use any portion of a prairie dog colony for feeding, obtaining shelter and raising young. This happens when burrows collapse, fill in with soil or water or are excavated or otherwise blocked. Critical habitat is also destroyed if the vegetation community is changed dramatically and becomes too tall or obstructive, causing difficulty for ferrets in movement between burrow holes to obtain shelter, or increasing potential cover and perching opportunities for predators. The prairie dogs maintain this vegetation at levels suitable for the ferrets. Destruction of the critical habitat could happen due to physical alteration of the land or if the prairie dogs on a colony are destroyed and the colony is therefore no longer maintained. The fact that some pastures contribute to ferret habitat is evidence of the importance of large-scale grazing ecosystems. Proper grazing management and associated activities are compatible with critical habitat. Creation of new shallow pipelines may be compatible with critical habitat. Management practices that do not constitute destruction of critical habitat include the use and maintenance of:

  • existing fence lines;
  • existing shallow water pipelines and dugouts;
  • salting locations;
  • existing prairie tracks for vehicles including two-track trails; and
  • existing and emergency fire guards.

Some examples of activities that may result in destruction of critical habitat, include, but are not limited to:

  • cultivation;
  • gravel extraction;
  • industrial exploration, development and infrastructure;
  • construction of new permanent fire guards;
  • deliberate flooding or filling;
  • anthropogenic development (including roads or buildings); and
  • destruction of enough prairie dogs (ie. shooting, poisoning or other killing activity) to destroy the function of the prairie dog town for a ferret (ie. ability to obtain food and maintain habitat)

In contrast, pre-existing agricultural activities, like sustainable livestock grazing, are compatible with critical habitat for ferrets. Existing roads are not included in the description of critical habitat and therefore road maintenance activities are not likely to result in destruction of critical habitat.

Only some of these activities alone, such as cultivation and flooding, are likely to destroy critical habitat. However, there are probably thresholds or threshold zones of habitat loss, habitat fragmentation, and changes to habitat conditions beyond which their cumulative effects would jeopardize the ability to achieve the recovery population and distribution objectives (Huggett 2005, Lindenmayer & Luck 2005, Jager et al. 2006, Bets et al. 2007, Rhodes et al. 2008). The cumulative effects of some combination of these activities could alter the habitat attributes and functions beyond a threshold necessary to achieve the population and distribution objectives for the species' recovery. Unfortunately these threshold values are unknown for ferret critical habitat at the time of writing of this document.


2.6.3 Schedule of studies for identification of critical habitat

 

Table 3. Studies linked to identification of critical habitat of black-footed ferrets in Canada
ActionCompletion date
Complete the Action Plan for the Black-footed Ferret in Canada and reintroduce ferrets.September 2009
Monitor ferrets post-release and estimate carrying capacity of current prairie dog colonies.August 2011
Monitor success of reintroduction and determine necessity of increasing prairie dog colonies inside and outside Grasslands National Park.March 2011
Incorporate black-footed ferrets into a multi-species action plan and identify ferret critical habitat in conjunction with other species that share the same habitat.June 2011

2.7 Effects on other species

The impact of black-footed ferret recovery activities on co-existing species in Canada is largely unknown (see Knowledge Gaps section 1.7). A brief summary of the potential effects of ferret recovery on non-target species, natural communities and ecological processes is provided in Table 4.

Working cooperatively with the affected species' recovery teams can mitigate many of the identified negative effects of black-footed ferret recovery on co-existing species. The effects on other species will be closely monitored and a meeting of all prairie recovery teams will be proposed each year to discuss issues that impact multiple species. Conducting proper pre-release quarantine procedures on all black-footed ferrets, and maintaining current Canine distemper virus (CDV) and rabies vaccination status for all released and wild-born ferrets can reduce the potential for negative disease effects.

Minimizing the effects of increasing prairie dog colonies as much as possible can mitigate negative impacts on the habitat of other species. This can be accomplished by avoiding the expansion of prairie dog colonies in areas where rare plants or sagebrush communities occur. Insecticidal dusting of prairie dog burrows may be conducted as part of a plague response plan if the onset of sylvatic plague is detected in a prairie dog colony. This can have a positive effect on the prairie dogs and ferrets but a negative effect on the invertebrate fauna.

Ferrets, prairie dogs and other potentially affected species will be monitored closely post-release and any significant effects on other species at risk will be mitigated in conjunction with the relevant species at risk recovery teams. These mitigation measures will be outlined in the ferret action plan. Although not anticipated, if a species at risk becomes clearly imperilled due to the effects of ferrets, the ferrets may have to be removed from the area. If this is found to be the case, the decision to remove ferrets will be made on recommendation by the jurisdictions on the Saskatchewan Species at Risk Coordinating Committee with advice from the relevant recovery teams.

 

Table 4. Potential effects of black-footed ferret recovery actions on co-existing non-target species and natural communities
Species or communityAnticipated effectImpact of effectLikelihood of occurrenceImportance of effect
Black-tailed prairie dogs (Special Concern)Direct predation by black-footed ferretsUnknown, may be negativeCertainUnknown
(May be negligible, but could affect population levels if combined with stressful conditions such as drought and hibernation.)
Black-tailed prairie dogs (Special Concern)Increase in habitatPositiveProbableModerate
Black-tailed prairie dogs (Special Concern)Increased disease riskNegativePossibleUnknown
(See section 1.7)
Burrowing Owls (Endangered)Direct predation on adults, young and eggs by ferretsNegativePossibleUnknown
[See section 1.7. Burrowing owls occur on almost every current ferret reintroduction site in the U.S. with no apparent impact of ferret predation on the owls at the population level (Livieri pers. comm.).]
Burrowing Owls (Endangered)Increased nesting habitat with expansion of prairie dog coloniesPositiveProbableUnknown
Burrowing Owls (Endangered)Increased disease potential with expansion of prairie dog coloniesNegativePossibleUnknown
(See section 1.7)
Swift foxes (Endangered)Increased habitat through prairie dog colony expansionPositivePossibleLow
[Other habitat elements and predation may be greater limiting factors (Moehrenschlager et al. 2004).]
Greater Sage- Grouse (Endangered)Predation of eggs and young by ferretsNegativePossibleUnknown
(Not thought to be important in the U.S. ferret recovery program. See section 1.7.)
Greater Sage- Grouse (Endangered)Habitat loss through prairie dog colony expansionNegativePossibleNegligible.
(The prairie dog expansion being considered in this strategy is limited in scope and will occur away from sage grouse nesting habitat.)
Mountain Plovers (Endangered)Predation on adults, young and eggs by ferretsNegativeUnlikelyNegligible
(No recent nests found in the Grassland National Park region.)
Mountain Plovers (Endangered)Increase habitat availability through prairie dog colony expansionPositivePossibleLow
(No recent nests found in the Grassland National Park region despite the existence of prairie dog colonies.)
Plains bisonDecreased grazing capacity with prairie dog colony expansionNegativePossibleNegligible
(Very low grazing levels planned for Grasslands National Park.)
Prairie rattlesnakesIncreased prey availability through predation on ferretsPositiveProbableUnknown
Prairie rattlesnakesIncreased habitat availability through increases in prairie dog coloniesPositiveProbableUnknown
Golden Eagles and Ferruginous Hawks (Special Concern)Increased prey availability with increased prairie dog populationsPositiveProbableLow
Richardson's ground squirrelsDirect predation by ferretsNegativeProbableUnknown
(Although black-footed ferrets prey almost exclusively on prairie dogs in the U.S., historical data suggests ferrets may have exploited alternative prey sources more extensively in Canada. See sections sectionsection 1.3 and sectionsection 1.4.1.)
InvertebratesIncreased mortality through insecticidal dusting for sylvatic plague controlNegativePossibleUnknown
(Dusting also affects non-target endemic and beneficial invertebrates that provide prey for insectivorous species. See section 1.7.)
HerptilesDirect predation by ferretsNegativeUnlikelyNegligible
(Black-footed ferrets feed almost exclusively on prairie dogs. See section 1.4.1.)
HerptilesIncrease habitat availability through prairie dog colony expansionPositivePossibleLow
(Herptiles in Grasslands National Park do not appear to rely extensively on prairie dog colonies for habitat.)
Rare plantsHabitat loss through prairie dog colony expansionNegativePossibleLow
(Prairie dog colony expansion can be conducted in a manner that avoids areas with rare plants.)
Rare plantsIncrease habitat availabilityPositivePossibleLow
(Rare plants in Grasslands National Park do not appear to rely extensively on prairie dog colonies.)
Late successional native prairieDecreased biodiversity of endemic or unknown species through prairie dog colony expansionNegativePossibleLow
(Prairie dog colony expansion can be conducted in a manner that avoids areas with rare plants.)
Sagebrush communitiesReduction of sagebrush habitatNegativeProbableModerate
(Prairie dog colony expansion can be conducted in a manner that avoids areas with rare plants.)
Other native predatorsIncreased mortality or displacement for common ferret predatorsNegativePossibleLow
(Predation mortality will be primarily reduced by preconditioning release ferrets. See section 2.1.)
Other native predatorsIncreased risk of disease (sylvatic plague, CDV and/or rabies)NegativePossibleLow
(The presence of sylvatic plague, CDV and rabies has already been documented in southern Saskatchewan. All released ferrets will undergo appropriate quarantine procedures and be vaccinated for CDV and rabies. See section 2.1.)
Other native predatorsIncrease prey availability through prairie dog colony expansion and ferret themselvesPositiveProbableLow

2.8 Statement on action plans

The Action Plan for Black-footed Ferrets in Canada will be completed by September 2009.