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COSEWIC assessment and update status report on the swift fox (Vulpes velox) in Canada (2000)
- Assessment Summary
- Executive Summary: from the 1998 Status Report
- Population Size and Trends
- General Biology
- Limiting Factors
- Special Significance of the Species
- Evaluation and Proposed Status
- Literature Cited
- Project Notes and Reports
- The Author
Three fossil teeth belonging to a very "small" fox were found among early Blancan (late Pliocene) mammal remains in Texas (Dalquest 1978). Vulpes velox finds in Texas were from the Pleistocene period and from late Wisconsinan to Holocene cave deposits in eastern Missouri (Kurten and Anderson 1980 and Parmalee et al., 1969). Those areas are outside of the current range of the swift fox and are indications of long term changes in swift fox distribution.
The Alberta Provincial Museum, Edmonton, Alberta has a number of specimens, some of which appear to be those of swift fox, although verification is still required. These were obtained from Exshaw, Stettler, Highwood area (Calgary); Balzac and Calgary (J. Burns pers. comm.). Published information for Alberta is available from specimens found at January cave, Alberta. There is some question as to the dates, however, material recovered ranged in age between about 23,000 to 33,500 BP (Burns, 1991).
North American distribution
The swift fox is native to the North American short/mixed grassland prairies of the Great Plains region. Suitable swift fox range in Canada is restricted to the southern portions of the prairies, namely Alberta, Saskatchewan and possibly Manitoba. This region coincides with the northern edge of the continental range of the species.
It is difficult to reconstruct the size of the historical range of swift foxes on the continent. One estimate (Scott-Brown et al., 1987) places it at 1.6 million km2 (624,000 mi2). This would include the area from central Texas, north to central Alberta and from the Rocky Mountains to about 95o west longitude, or further east to west between western Iowa and the eastern half of Colorado (Fig. 1). Historical range maps include western Minnesota and Iowa (Hall 1981, Scott-Brown et al., 1987, Samuel and Nelson 1992, Fauna West 1991) but specimens were never (as far as is known) obtained from these areas for verification (Swanson et al., 1945; Allen 1870; Bowles 1975 and Kahn et al., 1997). A rough estimate, based on vegetation mapping, (Kahn 1997 et al.) is that the species currently can be found in about 40% of its former U.S. range.
The ability by management agencies to accurately assess numbers is still open to wide interpretation. In a status evaluation of swift foxes in the United States, the United States Fish and Wildlife Service initially upheld a 1992 drafted petition to list the species as a candidate endangered species. After the 90 day finding, the USFWS initiated a 12-month finding to further review the status. That review resulted in the conclusion that the swift fox was deemed extirpated in most of its original historic range and found only in isolated pockets in remaining grassland areas. The official designation of the swift fox was that it was indeed a valid endangered species candidate and, listing was "warranted but precluded" by the need to address other, higher priority species at risk.
The distribution was probably always patchy and disjunct in some areas and continuous in others (Hoffman et al., 1969; Pfeiffer and Hibbard 1970; Moore and Martin 1980; Fitzgerald et al., 1983; Giddings and Knowles 1995; Kruse et al., 1996; Allen, 1996). In general, the U.S. range included Colorado, Wyoming and Montana, Kansas, Nebraska, North and South Dakota and western Oklahoma and Texas. After major declines up to the turn of the century, and in some areas (e.g. South Dakota) as recently as the 1960's and 1970's, the species has made a slight comeback.
Current knowledge of continent-wide abundance and distribution is incomplete. The potential short grass/mixed grass prairie ecoregion currently mapped in North America (Figures 2 and 3) is possibly 20% less than the most "optimistic" historic swift fox range as one could expect from the literature. The original distribution of the species was primarily influenced by the extent of native prairies. This is still the case for most areas but exceptions do occur.
Human activities in the late 1800's and first quarter of the 1900's changed the prairie landscape (Coupland 1950 - see also section on habitat degradation). Loss of prairie habitat, predator control, unregulated trapping/hunting, rodent control, road construction, widespread use of pesticides/herbicides, loss of other grassland faunal components (e.g. bison, wolves) and long term climatic changes have all been implicated in the reduction of swift fox numbers in the United States and complete extirpation in Canada. The above list represents suppositions, about which there are no empirical data to define precise reasons for reduction in swift fox populations on the continent.
Figure 1. Rough approximation of the possible maximum range of swift foxes on the North American continent during the 19th century and approximate distribution in 1997.
Figure 2. A map showing approximately the extent of short/mid grass prairie areas on the North American continent, based on a modified interpretation by Lauenroth (1966) and the Canadian Prairie Conservation Action Plan.
Figure 3. A map indicating distribution of potential swift fox range in the United States. Dispersal barriers, that could isolate populations and prevent gene flow, are shown stippled. Also indicated are trapping sites from which swift foxes were obtained for the Canadian re-introduction program.
Historical - to the 1930's
Historically, swift fox were present in southern Alberta (north to the 53rd parallel - Soper 1964), southern Saskatchewan and possibly in south-western Manitoba (Pattimore, 1985). The last confirmed specimen in Canada was taken in 1928, near Govenlock, Saskatchewan, 14 km east of the Alberta/Saskatchewan border and 28 km north of the U.S. border. An unconfirmed record was reported by Looman in 1972.
Current - 1983 to 1997
Since introductions began in 1983, the swift fox range in Canada has been delineated by Carbyn (1996) and was updated by Cotterill (1997b). None of the previous maps included areas of dispersal. Figure 4 incorporates information on suitable and unsuitable habitat dispersal locations and core areas, respectively. This map incorporates information available to date, on an approximation of swift fox habitat as determined from GIS mapping on a pixel of 1 km by 1 km. Core areas are identified as Core area 1 (Lost River Ranch - Border area) and Core area 2 (Grasslands National Park - Wood Mountain area). The land-cover information used in Figure 4 is based on National Oceanic and Atmospheric Administration (NOAA), Advanced Very High Resolution Radiometer (AVHRR) satellite imagery that was taken during the summers from 1988 and 1991. The imagery was classified by the Manitoba Remote Sensing Centre into broad landcover types at a resolution of 1 kilometre. The classified land-cover map was imported into Arcview software and converted into polygon format. The Arcview files were used to calculate the area of interest in this report and for illustration purposes.
It would be a misconception, and a misrepresentation of facts, if the current "potential range" is accepted as the "present range" of swift foxes in Canada and in the United States. There are vast spaces outlined in Figures 3 and 4 that likely do not have swift foxes at the present time. The challenge in future, is to evaluate the suitability of these areas for swift foxes and, if warranted, continue releases at these sites. Alternatively, abilities of foxes to disperse to these sites from core population areas, could be investigated.
The current population distribution in Canada and adjacent Montana is the result of an ambitious 14 year re-introduction program (Schroeder 1982; Russell 1983; Reynolds 1983, a, b; Russell et al., 1984; Russell and Scotter 1984; Scott-Brown and Reynolds 1984; Scott-Brown and Herrero 1985; Herrero and Mamo 1987; Herrero et al., 1989; Mamo 1987; Mamo 1988; Mamo 1994, a, b, c; Mamo 1995; Mamo et al., 1990; Mamo and Herrero 1987; Mamo and Sturgess 1991; Carbyn 1986; Carbyn and Schroeder 1987; Carbyn 1990; Carbyn 1996; Carbyn and Killaby 1989; Carbyn et al., 1993; Carbyn et al., 1994; Brechtel et al., 1993; Brechtel et al., 1994; Brechtel et al., 1996; Hjertaas 1994; Fisher 1993; Harris and McAdam 1994; Cotterill 1997 a, b; Taggart 1994; Moehrenschlager 1994; Smeeton 1994; Smeeton 1996).
Figure 4. Map showing approximate distribution of swift foxes inCanada. It includes information from surveys and from records of animals that have dispersed from the core reintroduction sites along the Alberta/Saskatchewan border and the Grasslands National Park areas.
The suspected swift fox range for 1997 was defined by information obtained from sites of releases, dispersal, telemetry locations, casual observations, road kills and monitoring of collared animals during a number of studies (Mamo 1994; Pruss 1994; Carbyn et al., 1994). The core areas under consideration in Canada extends west of Manyberries, Alberta to east of Grasslands National Park in Saskatchewan and includes all or part of 108 townships.
A summary of the areas illustrated in Figure 4 is shown below. This is a first approximation of native prairie habitat found in core areas 1 and 2 and in peripheral areas in Alberta and Saskatchewan. Data requires further investigation.
|Total land Area||Total native prairie||%|
|Core 1 -||5,400 km2||5,100 km2||94%|
|Core 2-||4,200 km2||3,400 km2||81%|
|Periphery-||45,400 km2||24,200 km2||53%|
The areas outlined in white (Fig. 4) contain some lands that are likely suitable habitat for swift fox while areas in gray are cultivated lands. The map does indicate the potential range in which subpopulations could exist within a larger metapopulation. The extent to which movements between sub-populations will occur depends on the ability of swift foxes to disperse, the nature of the areas in between sub-populations and the distances between suitable areas.
Canadian reintroduction program
The repatriation of the swift fox was due solely to the reintroduction program. It is inconceivable that foxes could have survived previous to the reintroductions in "pockets" without detection. Rumours did abound of the possible survivors, but such reports remained unsubstantiated, despite the fact that as recently as 1970 it was still believed that swift foxes occurred in very low numbers in their former ranges on the Canadian prairies (Novakowski 1970).
Foxes are vulnerable to trapping. It is a virtual impossibility that from 1928 (year of last official record) to 1983 (year of first official releases) - a span of 55 years - they could have remained undetected where trapping occurred. Clearly the reintroduction program carried out from 1983 to 1997 brought back this small carnivore to some areas of former abundance in southern Alberta, southern Saskatchewan and northern Montana. In 1983 the first official releases took place, however, this was not the first release. Prior to any formal activities, one private zoo from Edmonton had released 4 foxes into the Grasslands National Park area in 1976. Although highly publicized through a television program, this release was an unofficial one (Al Oeming pers. comm.) It is unlikely that a release of these 4 animals resulted in the establishment of a population.
The subsequent process of returning the species to its former range was a lengthy one. The first initiatives for captive breeding were at Calgary Zoo and Alberta Game Park (Polar Park), Edmonton, during the 1960’s. The Alberta Game Farm foxes originated from Utah and were first bred in Alberta in 1961 (Al Oeming pers. comm.). Much of the leadership in captive breeding subsequently was through the Cochrane Wildlife Reserve (previously known as the Wildlife Reserve of Western Canada). A vixen (possibly two, the record is not clear ) from the Alberta Game Park was given to the Cochrane Wildlife Reserve in 1976 (Smeeton 1984). Cochrane imported two pairs of foxes in 1972. These beginnings grew into a major program involving four federal/provincial agencies and six non-government organizations. The Canadian Wildlife Service (CWS) officially became involved in 1978, when COSEWIC (Committee on the Status of Endangered Wildlife in Canada) classified the species as "extirpated" (Russell and Zendran 1983).
From 1984 to 1989 the project was guided by a Technical Committee. In April 1989 the Technical Committee was replaced by the National Swift fox Recovery Team under RENEW (Recovery of Nationally Endangered Wildlife). The team initially consisted of representation from Alberta, CWS, Saskatchewan and University of Calgary, Faculty of Environmental Design. In 1993 the Calgary Zoo was also represented on the Recovery Team and in 1994 the Cochrane Wildlife Reserve, Edmonton Valley Zoo, Swift Fox Conservation Society and Parks Canada were added to the team, while the involvement of the University of Calgary and Calgary Zoo was terminated. Through very effective programs, the Cochrane facility has been able to generate impressive financial backing for captive breeding of foxes. The swift fox stud book was initially kept by the Calgary Zoo and reverted to the management of the Cochrane Wildlife Reserve in 1994. By 1997 the Cochrane Wildlife Reserve had changed its name to the Cochrane Ecological Institute, and ownership of the foxes was transferred from CWS to that facility. Prior to 1985 (from 1973-1985) the Smeeton family owned the captive foxes held on their ranch.
Because of the unique history and evolution of the program through different stages, the project, from its inception, was not based on an approved recovery plan. It developed from private initiatives (1961 and 1973), to a university project (1977) with some governmental support, to an interagency co-operative program (1984). Letters of agreement between provincial and federal governments had expired by 1989 and were renewed to 31 March 1994 and March 1997 respectively. Documents which initially placed the program into perspective, were a student thesis and reports of CWS projects done through the University of Calgary (Carlington 1978; Carlington 1980; Russell and Zendran 1983; Reynolds 1983; Schroeder 1985; Carbyn and Schroeder 1987).
A considerable amount of field work had been carried out by 1989. However, a general framework for operation was still lacking. The newly appointed Recovery Team set out to develop options and a management strategy. Without the lengthy trial and error period, none of the information we had on the responses of the foxes to different release techniques and to different environmental conditions, would have been available. When the Recovery Team was established in April 1989, it had available to it a wealth of information upon which to build a program. A schedule was set and maintained throughout. In a series of meetings in 1989, the then newly formed Recovery Team presented management authorities with three options. After reviews by the Director, CWS, Western and Northern Region, the Director, Wildlife Branch, Alberta Fish and Wildlife, and the Director, Wildlife Branch Saskatchewan, a program was approved in 1992, and the appropriate funds allocated for extension of the program.
The overall objective was to first determine if reintroduction of the species into the Canadian prairies was feasible and, if so, to recommend whether or not a full scale recovery program was possible. The renewed efforts (beginning in 1989) outlined 3 initiatives: 1) using more wild captured foxes for hard releases; 2) releasing foxes in spring and comparing results with fall releases; 3) diversify locations, choosing wetter sites as a hedge against drought.
The measures of success for the 3 year program were identified. These were set by establishing minimum criteria, namely that on one release area, 15% or more of the animals released survive for at least one year in two out of three years; and that the annual recruitment of the surviving population should offset annual mortality in each year on at least one of four release sites.
By 1992, it was obvious that it was feasible to reintroduce the species (Brechtel et al., 1993) and in order to maintain the momentum a further 5-year program (to 1997) was to be carried out. Specific directions were for the Recovery Team to prepare a 5‑year Recovery Plan which was to include several key elements:
1. Continuation of releases of swift foxes for a further 5 years (1992 to 1997).
2. Monitoring of the wild population to guide future releases and assess program success.
3. Importation of swift foxes from Wyoming for release to the wild in Canada.
4. Continuation of captive-breeding, provided that breeding facilities can finance their own operation without direct government agency support.
5. Minimizing the number of captive foxes requiring long-term care after the program ends. All breeding foxes were to be released before they reached five years of age.
6. Provincial agencies to lead the release and monitoring programs, the Canadian Wildlife Service to lead sourceing of swift foxes from Wyoming and from captive-breeding facilities.
7. The Canadian Wildlife Service was to be the lead agency in developing research projects designed to evaluate the habitat requirements, survival and ecology of swift foxes in the northern extremity of their range.
Releases using both wild-captured (U.S. foxes) and captive-raised foxes continued from 1993 to 1997 with the exceptions of 1992 and 1993, when only captive-raised foxes were released. Three significant events dominated this period of time. Starting in 1994, research programs involving the Canadian Wildlife Service, the University of Oxford (Oxford, England) and the University of Alberta (Department of Renewable Resources) were carried out in the core areas of the current range. Prior to 1994, feasibility plans and research were also conducted through the Faculty of Environmental Design, University of Calgary (Carlington 1980, Reynolds 1983a, Schroeder 1985, Pruss 1994). The Canadian Wildlife Service continued to provide major portions of funding from A-base sources and provided vehicles, equipment and accommodation in the field for all studies. Secondly, a detailed multi-agency survey of the numbers of foxes was carried out in the winter of 1996/97 (Cotterill, 1997a). This survey involved all government agencies and others and was very much a co-operative effort. Thirdly, the ownership of the captive colony of foxes at Cochrane was passed on from the Canadian Wildlife Service to the Cochrane Ecological Institute in June 1997. Several significant research efforts were carried out on captive foxes at the Cochrane Ecological Institute. These resulted in a study by E. Teeling (M.Sc., 1996, University of Edinburgh) and a study by S. Bremner (M.Sc., 1997, University of Edinburgh).
Soft and hard releases
The soft release method emphasized placing paired foxes into pens in the field during the fall, wintering them at these locations and releasing family groups in the following spring/summer. In the hard release program, foxes were transported from the captive facilities and released into the wild without prior conditioning in field pens (Carbyn et al., 1994). From 1983 to the fall of 1987 all releases of captive bred foxes had involved the "soft release" method. The number of pairs of foxes released in the soft release program are summarized in Table 1. The total number of foxes released (adults plus offspring) was 137 foxes. In a sample of 200 foxes (45 soft released and 155 hard released foxes), survival to 6 months was 55% and 34% respectively; to 12 months it was 31% and 17% and by 24 months it evened out to 13% and 12% respectively.
The soft release program was discontinued because it was labour intensive, costly and provided fewer foxes than the hard release program. Fall releases were carried out from late August to October, when the young were thought to normally disperse, although more recent evidence (A. Moehrenschlager et al. in prep.) seems to indicate that dispersal may be less prevalent than previously thought at this time.
After 1987, all releases of captive-raised and wild-caught foxes used the hard release technique (Table 2). A breakdown as to foxes released in the West Block and the East Block within Grasslands National Park is summarized in Table 3.
1"Collared" foxes lists those which had radio transmitter collars attached in order to track survival anddistribution.
1Four of these foxes were held in captivity after capture in the U.S.A. in 1988 and designated as captive foxes in this table, as they had been conditioned to confinement.
The Canadian re-introduction program depended on both captive-raised and wild‑born foxes. It was necessary to import foxes from the U.S. in order to have breeding foxes in captive facilities. The Alberta Game Farm, near Edmonton was the first Canadian facility to raise swift foxes during the early to late 1960's.
Since 1983, the Wildlife Reserve of Western Canada, near Cochrane, Alberta, was the main source of captive-raised foxes. A steady supply of captive-raised foxes provided the nucleus for the reintroduction program. Other facilities involved at a later stage were the Calgary Zoo (1983-1994), Moose Jaw Wild Animal Park (1984-1995), and Valley Zoo in Edmonton (1989-1997). There are two other Canadian facilities (Kamloops Zoo and Forestry Farm Zoo in Saskatoon) that hold swift foxes for display purposes. In 1996 there were 16 Canadian zoos listed as accredited by the Canadian Association of Zoological Parks and Aquariums (Dave Leeb pers. comm.), which increases the potential for future display of captive swift foxes for public education programs.
The total number of foxes imported for the official program, from the United States is shown in Table 4. Over the years, there was a lively debate over the merits of releasing captive-raised foxes versus wild-caught foxes. Initial hard release efforts (1983 to 1989) used wild-caught foxes in smaller proportion (18 out of 344) than in later years (66 out of 535). Overall ratio was 84 wild-captured to 795 captive-raised or 1:10. These figures do not include foxes born in soft release pens.
One component of the debate has centred on the negative aspects of removing animals from the wild, thus reducing numbers world-wide. This is relevant, if overall numbers are low, but less relevant if the species still is widely distributed and existing at high densities in portions of its range. Releasing captive-bred stock adds to the world’s population while translocation does not. Capturing was carried out in the wild, without the benefit of population estimates to determine the impacts of removal of foxes from established populations. This may become an important consideration, if the wild capture of foxes is to continue for re-introduction purposes.
- Date Modified: