by Lu Carbyn *
The swift fox was extirpated in Canada, largely as a
result
of human activities. A major reintroduction programme seeks to
restore
them to their former range.
[Ed. - we plan to post the figures on-line soon!]
When the first European explorers penetrated westward on the North American continent they encountered a faunal complex quite different from what it is today. Bison herds (Bison bison) dominated the landscape. Wolves (Canis lupus) and grizzly bears (Ursus horibilis) shared the plains with the numerous Indian tribes. Other predators benefited from the mix of faunal elements on this landscape. The smallest of the canids, the swift fox, was considered common by those naturalists and explorers who kept notes of what they saw (FaunaWest 1991).
Sometime in the late 1800s and 1900s this delightful, cat-sized carnivore declined in range and numbers in the northern prairie areas and major reductions were recorded for more southerly prairie regions. In Canada the last officially recorded swift fox in a museum collection was obtained in 1928. Obviously, stragglers probably persisted here and there but the Canadian population vanished within a period of only a few decades. Swift foxes in the states of Montana and North Dakota were also reduced to the point of virtual extinction. South Dakota was an interesting special case. The last record of swift foxes in that state was reported by Visher (1914-citation from FaunaWest 1914) and the species remained unrecorded until 1966 (McDaniel 1976-citation from FaunaWest). Within the next 15 years numbers in South Dakota increased somewhat (Hillman and Sharps 1978) and populations were noted in two different counties. Foxes were not reported in Wyoming for many years until they seemed to reappear in the late 1950s (Long 1965). Swift foxes were not apparent In Nebraska between 1901-1953. In the 1960s and 1970s the little fox appeared to make modest comeback, but numbers were again reduced in the 1990s (FaunaWest 1991).
The demise of the species in Canada went largely unnoticed at first. Old-timers still talked about those ·leather eating kit foxesº, but beyond that no one payed much attention until a greater awareness of the environment penetrated the consciousness of North American society in the latter part of the 1960s and 1970s. By chance, an eccentric, globe trotting couple were looking for new adventures and decided to set up a game farm. Among an eclectic collection of wildlife species they included swift foxes as part of their menagerie. This was a stroke of good fortune, as the captive founder foxes eventually became the core of a major re-introduction project. A University professor with graduate students forged links with the private initiative and began a process that continues today, namely a long term reintroduction programme. Government agencies, slower to respond to specific needs, became involved as well. In 1978 an official committee (COSEWIC: Committee on the Status of Endangered Wildlife in Canada), comprised of many agencies and charged with the responsibilities of reviewing the status of rare, threatened or endangered species, officially declared the swift fox as "extirpated" (meaning once a native species, existing in Canada, but currently extinct although still existing elsewhere on the continent).
The decline of the swift fox and its demise in Canada are unlikely to have been caused by just one factor. Possible explanations include: (1) habitat loss through conversion of native prairies to agriculture; (2) species' vulnerability to human activities such as trapping, predator control, shooting, collisions with vehicles; (3) use of rodenticides to control prey populations; (4) introduction of diseases from domestic farm dogs; (5) weather and winter severity; (6) interspecific competition from a mix of competing carnivores, including other canids such as wolves, coyotes (Canis latrans) and red foxes (Vulpes vulpes).
Swift foxes often tend to be docile, unafraid, curious and inquisitive which renders them vulnerable to a number of mortality agents. They are small, and therefore exposed to a host of potential avian and mammalian predators. Attributing the demise solely to direct human interference (persecution of predators and habitat destruction) is probably unjustified. European influences on predator control were much more severe and appeared earlier in the south than in the northern portions of the species' range. The same could be said in general for habitat destruction, yet swift foxes survived in remnant pockets in the south whilst northern populations vanished. However, indirect results of human pressures are likely to have had an unfavourable impact on the species. Coyotes can more effectively access a range of resources from mice to deer and in the scheme of evolutionary processes benefited from European settlers, while swift foxes were being squeezed out of the ecosystem.
In an evolutionary context we have experienced major shifts within the canid guild on the North American Great Plains (Sargeant 1982). The red fox expanded its range from 1801-1900 but remained scarce between 1901-1930. Numbers then increased rapidly between 1931-1980. Human persecution of grey wolves on the Great Plains was followed by increased coyote populations. Coyotes in turn have impacted red foxes (Sargeant and Allen 1989 and others). Competition may be food related or exploitive (where one species kills another). The outcome of coexistence and competition may be influenced in subtle ways by topography, snow cover, seasonality, food abundance, population characteristics, niche overlap and the overriding influence of humans, which can impact in a multitude of direct and indirect ways. By changing the environment for swift foxes (i.e. eliminating wolves, creating an environmental mosaic enhancing the survival of competitors such as coyotes/red foxes) man's hand may well have dealt the "little fox on the prairie" a double blow, firstly through direct elimination (shooting, trapping, poisoning) and secondly by giving competitors a "leg up". The question therefore, that faced both academia and government administrators in the mid 1970s was "does the swift fox niche still exist in an altered prairie landscape?" The social climate was such that an expenditure on experimental release programmes was warranted.
Miles and Beryl Smeeton imported the first two pairs of swift fox from the United States in 1972 and obtained another pair from a game park (provenance unknown). The Smeeton estate, first called the Wildlife Reserve of Western Canada and now the Cochrane Wildlife Reserve (a change brought about by their daughter, Clio Smeeton) became the important centre at which captive foxes were raised. This facility also served the purpose of raising the public profile of the project as it provided a ready supply of animals for media attention. Steven Herrero (University of Calgary), Richard Russel (Canadian Wildlife Service) and a number of graduate students developed ideas concerning reintroduction of the species to the wild. The first foxes were released in Alberta in 1983 using a "soft release programme": paired foxes were held in release pens (3.7m x 7.3m) constructed in prairie habitats and fenced for protection from disturbance by free-ranging cattle. The foxes were placed in the pens in October and held during the mating season. If they had produced young, the adults and the offspring were released from these pens during the summer. This release method was expensive, time consuming and there was no evidence that it was more effective than hard releases. Soft release pens in fact attracted coyotes and potentially rendered swift foxes more vulnerable to coyote predation. From 1987 hard releases were used, in which swift foxes were transported from the captive facilities and released directly into the wild without prior conditioning in release pens (see adjacent photo).
From 1989 to 1994 the programme was directed through a Recovery Team, with representation of federal and provincial agencies, University Institutes and Zoological gardens. An experimental programme from 1989 to 1992 (Brechtel et al., 1993) tested the efficacy of different techniques and was designed to determine if the niche for swift foxes does still exist in the Canadian prairies. About 30% of the foxes released were monitored for survival, using techniques to evaluate relative survival rates of wild-captured versus captive-raised foxes, survival of spring-released versus autumn-released foxes, and assess releases into areas with moister habitats.
Throughout the initial period it was questionable whether conditions for the re-establishment of a fox population were still present on the prairies. More conclusive proof came in 1990 when trapping was carried out from 3rd November to 7th December. Forty one foxes were caught of which 14 were marked (of known origin) and 27 unmarked (born in the wild). Most revealing was that three of the marked swift foxes had survived 3.5 years, two had survived 2.5 years and one had survived 1.5 years. Survival of released animals and young born in the field was proof that the niche for foxes was still present. Further confirmation of success emerged during another trapping effort in March, 1994. Mamo reported the capture of 13 foxes of which longest survivor, a fox named "Bert" (captured in the wild in Colorado in September 1988) had survived for six years after the release (Mamo, 1994).The current estimate is that there are about 150 foxes in the Canadian prairies.
Survival and successful denning is not proof that the population is self-sustaining over time. The goal for the programme, as defined in the Recovery Plan, is to "establish a viable, self-sustaining population of swift foxes, well distributed across suitable habitats on the Canadian prairies, which would result in the removal of the species from the endangered category by the year 2000."
The medium sized coyote (intermediate between wolves and red foxes) has extended its range following settlement of North America by Europeans. In nearly all areas where swift fox ecology has been studied it was established that coyotes kill and often do not consume swift foxes. Table1 lists the source of mortality of foxes studied in the Canadian release programme, showing the importance of competition with coyotes.
Similar figures have been obtained for Colorado, California (kit foxes) and Kansas. In the latter case, of 30 collared foxes 19 were found dead of which 17 were killed by coyotes and two killed on highways (L. Fox, pers. com.). If man's presence has encouraged coyote abundance, then the plight of swift foxes may have been indirectly affected by large scale landscape changes that influenced predator guild combinations. This may mean that swift foxes in future will survive in areas of lowest coyote densities, thus evolving to exploit different niches in the prairie mosaic. In the first swift fox vocalization surveys conducted in Canada, Wayne Harris of Saskatchewan found the greatest number of responses in farm/grassland interphase zones and not in core grassland areas. The suggestion is that in severe winters stockyards could provide conditions more conducive to survival than open grassland areas.
To date the Canadian project has depended heavily on access to American swift foxes, particularly from the state of Wyoming. A petition to declare swift foxes in the United States an endangered species was made in February 1992. The petition was upheld and a 90 day finding on the petition announced on May 23, 1994. The fact that swift foxes occur in highly disjunct populations in a much reduced portion of their range within the United States is cause for alarm. In many areas foxes are currently trapped and otherwise killed by man. Granting the species endangered species protection brings into play a new scenario. Killing of foxes will be illegal. This is likely to result in much lower human caused mortality, but it may also mean the loss of a supply of live-caught foxes for the Canadian Conservation programme. Prior to the announcement of the petition, the state of Wyoming had granted permission for the Canadian authorities to capture 150 foxes for the next five years. Twenty five foxes probably represents only a small fraction of the foxes currently killed by humans annually throughout its American range, and the capture of up to 25 foxes per annum from the wild American population could be considered an investment for the future of the species. However, American endangered species legislation carries with it a powerful impact; future access to foxes for the Canadian programme has not yet been determined. Clearly, a Canadian Recovery programme may need to be expanded into a North American Recovery plan. A hallmark of such an effort would be co-operation, where agencies from different federal, state and provincial jurisdictions can interact with other public and private interests in the conservation of the species. It may be that a major supply of foxes for future re-introductions, throughout the range, may depend exclusively on captive raised foxes. Such decisions can only be made if the true status of the species has been determined. This calls for the development of new survey techniques. In the Canadian projects we have experimented with scent post surveys, winter track counts, night lighting and breeding call surveys.
Studies thus far indicate that wild-captured foxes are more effective in a reintroduction programme than captive-born ones (Brechtel et al., 1993). Such wild-conditioned animals have greater experience in both avoiding enemies and capturing prey. In one comparison (1987-1990) the actual breeding population in the spring of 1991 indicated a roughly 1:1 ratio of residency as defined by den establishment, despite a 5:1 release ratio of captive-released to translocated foxes. The ratio of productive captive-raised foxes was 6/108 or 6%, versus productive translocated foxes of 6/19 or 32%. These statistics led Mamo to question the continued need for captive raised foxes on the programme (Mamo, 1994). On the other side of the debate is the effectiveness of supplying captive raised foxes to release sites not only in Canada, but possibly also to other areas in the United States from which foxes have disappeared, without manipulating already low established populations in the limited and reduced ranges where they now exist. The dilemma is "should we subject more captive raised foxes to trauma or death than would be the case had we used wild caught foxes instead (C. Mamo, op cit)" or should we disrupt already small populations in the wild instead? In the past the Canadian programme used both sources of foxes (Brechtel et al., 1993).
If wild established populations are our main concern then only captive foxes should be considered. In the modern world the concerns are also for individual animals; the loss of a larger number of captive raised foxes thus becomes a moral issue.
The Canadian Recovery effort is currently guided by a Recovery Plan, which calls for continued management and research. One outgrowth of the research programme concerns two student projects involving a coyote/fox home range study and a swift fox habitat/cattle grazing ecosystem study. Other initiatives to enhance survival of foxes during post release phases are being considered. One such initiative was mentioned by Smeeton in issue 2 of Canid News. The technique involved the use of protective shelters for captive released foxes. Funding for these projects has to come from both governmental and non-governmental sources. One problem to be overcome is that funding of student projects should not compete with captive breeding programmes. Priorities set by a Recovery Team thus need to take precedence over narrowly defined agendas of specific projects or other self-serving endeavours of specific agencies associated with a high profile conservation programme.
Clearly in the future a continental approach to swift fox conservation is needed. Several initiatives are already in place. In March 1993 the Canadian Wildlife Service initiated the first international workshop on the subject in Medicine Hat, Alberta. Plans are currently underway to organize a second such workshop for March 1996, at the same location.
Another recent initiative is a graduate student exchange programme in field research technology and methodology between Canada and Mexico. Two graduate students from Oxford University (Rurik List and Axel Moehrenschlager, under the direction of Dr. David Macdonald) will be working together. Other initiatives involving private institutions and public agencies are under way. In this age of globalization it is increasingly important to reach across borders and encourage cooperation between countries and among agencies. The Canadian experience can be useful in other parts of North America.
* Lu Carbyn is a senior biologist working with the Canadian Wildlife Service and is a member of the Swift Fox Recovery Team. He has years of experience working with canids, including wolves and coyotes.
© 1995 International Union for the Conservation of Nature and Natural Resources
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