Swift fox (Vulpes velox) COSEWIC assessment and status report 2009: chapter 2

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COSEWIC Executive Summary

Swift Fox Vulpes velox

Species Information

Standing 30–32 cm at the shoulder with a body mass of 1.6–3.0 kg, the Swift Fox (Vulpes velox) is North America’s smallest canid. Males are slightly larger than females. The fur is long and dense in winter. The upper parts are generally dark buffy–grey, the sides, legs, and beneath the tail are orange–tan, and the undersides are buff to pure white. In summer, the fur is shorter and more rufous. Swift Foxes have black patches on either side of their muzzles and black–tipped tails.

Distribution

The historic range of Swift Foxes extended from central Alberta, south to central Texas, and from North Dakota, west to central Colorado. In Canada, they originally occurred from the Pembina Hills in Manitoba, across southern Saskatchewan, and west to the foothills of the Rocky Mountains in Alberta. Having disappeared from Canada by the 1930s their current presence on the Canadian prairies is a result of a reintroduction program initiated in 1983. Most Swift Foxes currently occur in the southernmost portion of the prairies near the Alberta–Saskatchewan border, in and around Grasslands National Park in south–central Saskatchewan.

Habitat

Swift Foxes generally inhabit short– or mixed–grass prairie on level terrain or gently rolling hills. They usually select areas with short, sparse vegetation and topographic features like canyons, steep hills, or coulees. The quality of Swift Fox habitat is related to prey availability (particularly fossorial mammals) and predator abundance. They prefer relatively dry areas, and avoid cropland, fragmented habitats, and those with large elevation changes. Swift Fox range encompasses some of the most modified landscapes in North America, and conversion of native prairie to agriculture has been implicated as a primary reason for the historical range contraction of this species. Current estimates indicate that only 25–30% of original Canadian grassland habitat remains, and that at least 70% of native Canadian prairie has been converted for agricultural use. Energy development and associated road networks are currently the dominant agent of land use change.

Biology

Swift Foxes are opportunistic foragers that eat mammals, birds, insects, plants, and carrion, as well as bird eggs. Diet reflects the diversity and abundance of local prey species, and is highly seasonal. Swift Foxes either dig their own dens or modify those of other species. They are one of the most burrow–dependent canids, using dens throughout the year as refugia from predators, protection from extreme weather, shelter to prevent excess water loss, periodic resting cover, and as places to raise young. In Canada, Swift Foxes begin breeding in mid–February, and after a 51–day gestation, females have litters of 2–6 kits. Kits disperse between 9.5 and 18 months of age over distances typically less than 15 km from the natal area. Swift Foxes that survive their first year usually live for 3–7 years. They are territorial, with home ranges averaging 32 km² in size – larger than they are within core Swift Fox range, reflecting the more marginal habitat at the range periphery. Coyotes (Canis latrans) are the primary predator, followed by Golden Eagles (Aquila chrysaetos), and American Badgers (Taxidea taxus).

Population Sizes and Trends

The most recent population estimates in Canada indicate there are approximately 647 Swift Foxes in Canada, divided between the Alberta–Saskatchewan border (Border) population (513) and the Grasslands National Park (GNP) population (134). Over time, the populations from these two original reintroduction sites have become one meta–population, together with northern Montana, with evidence of long–distance dispersal throughout. Overall, Swift Fox populations in Canada increased by 130% between 1996 to 2006, although these estimates are overly precise because there are no confidence limits associated with these data. Swift Fox population density in Canada (Border and GNP populations only) is about 5.5 foxes/100 km², and the sex ratio is 52 males:48 females.

Limiting Factors and Threats

The primary well–documented natural factor limiting Swift Fox abundance and distribution in Canada is predation by Coyotes and Golden Eagles. Habitat loss, degradation and disturbance from development activities is a growing concern within Swift Fox range. Although there is no evidence to date that disease has caused significant Swift Fox mortality, the potential exists, in light of high seroprevalence to several diseases, the small and connected population, and the well–recorded incidence of disease having suddenly decimated other endangered canid populations. Competition with Coyotes and Red Foxes (Vulpes vulpes) are an additional potential limiting factor. Other threats to Swift Foxes in Canada include poisoning, trapping, and vehicle collisions.

Special Significance of the Species

Able to run at speeds of up to 60 km/h, Swift Foxes are one of the fastest animals in North America. As meso–predators, they are important to the biodiversity of the Canadian prairies. Swift Foxes also play a vital role in the spirituality of some of Canada’s First Nation cultures.

Existing Protection

Globally, the Swift Fox is ranked as Least Concern by the International Union for Conservation of Nature [IUCN] Red List of Threatened Species. In May 2000, COSEWIC assessed the Swift Fox as Endangered. Currently, the Swift Fox is listed on Schedule 1 of the Species at Risk Act. Provincially, Swift Foxes are listed as Endangered under the Alberta Wildlife Act and Regulation and the Saskatchewan Wildlife Habitat Protection Act. About 45% of Swift Fox captures during the 2005–2006 census were located within one Swift Fox home range on federal lands under various levels of protection.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal–Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non–government science members and the co–chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions
(2009)

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)*

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)***

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.