Description of residence for Swift Fox (Vulpes velox) in Canada

Section 33 of the Species at Risk Act (SARA) prohibits damaging or destroying the residence of a listed threatened, endangered, or extirpated species. SARA defines residence as: "a dwelling-place, such as a den, nest or other similar area or place, that is occupied or habitually occupied by one or more individuals during all or part of their life cycles, including breeding, rearing, staging, wintering, feeding or hibernating" [s.2(1)].

The prohibition comes into effect in different ways depending on the jurisdiction responsible for the species. Because the Swift Fox is not under pre-existing federal jurisdiction, the residence prohibition is only automatically in effect on federal lands on which the species occurs. SARA also contains a provision to prohibit the destruction of non-federal species' residences on provincial, territorial, and private lands by way of an Order by the Governor in Council (GIC), if the Minister of the Environment recommends it necessary to do so [s.34(2), 35(2)]. Unless such an Order is made, responsibility for this species remains with Provinces and Territories.

The following is a description of residence for the Swift Fox (Vulpes velox), created for the purposes of increasing public awareness and aiding enforcement of the above prohibition. Swift Foxes are known to have two types of residences - natal dens and shelter dens.

Assessment summary - November 2009

Common name - Swift fox

Scientific name - Vulpes velox

Status - Threatened

Reason for designation - This species was extirpated from Canada in the 1930s. Following reintroduction programs in Alberta and Saskatchewan initiated in 1983, they have re-established populations in these areas and in northern Montana. Population numbers and distribution have increased since that time, with the current estimate in Canada having doubled to 647 since the last COSEWIC assessment in 2000. Connectivity between populations has also improved during this time, particularly through northern Montana. Since 2001, population numbers and distribution have remained stable and habitat for this species within Canada appears to be saturated. Most improvement in overall population status can be attributed to populations in Montana, which are still demonstrating increasing trends in numbers and distribution. Deteriorating habitat in Canada and the threat of disease (as seen in other canids) could threaten the continued recovery of this species.

Occurrence - Alberta, Saskatchewan

Status history - Last seen in Saskatchewan in 1928. Designated Extirpated in April 1978. Status re-examined and designated Endangered in April 1998 after successful re-introductions. Status re-examined and confirmed in May 2000. Status re-examined and designated Threatened in November 2009.

Figure 1. Distribution of Swift Fox (Vulpes velox) in Canada (Environment Canada)

Figure 1. Distribution of Swift Fox (Vulpes velox) in Canada (Environment Canada)
Long description of Figure 1

Map of Southern Saskatchewan and Alberta showing the distribution range of Swift Fox (Vulpes velox) in Canada. The map was produced by Environment Canada. 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.

1) Natal den

Any tunnel and connected chambers used by a Swift Fox to give birth and rear kits is considered a residence.

Physical appearance and context

Swift Foxes are primarily prairie specialists and occur in short and mixed grass prairie in southern Alberta and Saskatchewan1. Swift Foxes often modify prairie burrows such as, but not limited to, badger (Taxidea taxus), black-tailed prairie dog, and Richardson's ground squirrel holes and use them as natal den sites2,3. In the spring and summer (circa April - August), den complexes typically having one or more central chambers connected to the surface by tunnels4,5 are used to rear young. Pairs in Canada have been documented to use up to eight different multiple entrance den sites during the kit birthing/rearing period9,10. The use of 13 different dens has been reported throughout one year6. The maximum number of dens used on the Canadian prairie may be greater if Swift Foxes are similar to Kit Foxes where the use of up to 50 dens per fox has been documented10.

Adult Swift Foxes are thought to choose dens based on their location and physical characteristics, particularly for the selection of natal den sites that usually have more entrances compared to temporary escape or shelter dens3,6,7,8. Additionally, at Swift Fox natal den entrances there are typically distinctive long, narrow dirt trailings compared to the mound of dirt at badger diggings.

On the Canadian prairie, the location and physical characteristics of Swift Fox natal den sites were compared to prairie burrows (typically badger)3. The model identified five variables (position on hill, distance from water, distance from roads/trails, new grass height, and slope of hills) that discriminated occupied dens from unoccupied sites with an overall classification success of 83%. Essentially, occupied natal dens (compared to unoccupied sites) used for rearing kits were not located randomly but were found on hilltops with gradual slopes, with relatively higher grass, further from water, and closer to roads and/or trails3.

Function

Natal dens provide a safe place for giving birth and rearing kits.

Damage and destruction of residence

Any alteration that destroys the function of single or multiple entrance natal dens would constitute damage or destruction of the residence. This would include, but is not limited to, habitat change near the den, including ploughing or disturbing native short or mixed grassland communities, particularly when such changes lead to the blocking or abandonment of a den.

In a report created for Environment Canada, setback distances were recommended for petroleum industry activities that affect species at risk12. In Saskatchewan, these recommended distances are 500m from a Swift Fox den for most activities during the February 15 to August 31, except for high-level disturbances (eg. permanent structures, roads) for which a setback distance of 2000m from a den is recommended. From September 1 until February 14 the recommended setback distances are 100m, 500m, and 2000m for low, medium, and high-level disturbances, respectively12. These setback distances were adopted by Saskatchewan Environment and Resource Management to be used as activity restriction guidelines for sensitive species in natural habitats13 Setback distances for Alberta in the Environment Canada report reflect the provincial guidelines.

Alberta Fish and Wildlife Division recommend setback distances from Swift Fox dens of 500m for all activities between February 15th and July 31st (breeding season)11. These setback distances change between August 1st and February 14th, to 50m for low-level disturbances such as surveying and monitoring, 100m for short-term vegetation disturbance (eg. low footprint seismic activities), and 500m for the creation of human structures, disturbance of soils or long-term vegetation disturbance (e.g., wellsite, powerline, pipeline, battery, road) 11.

Period and frequency of occupancy

Swift foxes are among the most den dependent of all canids and use natal and shelter dens throughout the year. Repeated use of dens by canids has been described for many North American canid species including the closely related kit foxes10, although each den is not necessarily used every year5,6,14. This repeated use of natal and shelter dens has also been observed for wild Swift Foxes in Canada7,9,10.

Dens used by parents and young between April 1 and August 31 are natal dens and should be considered as such for 5 years since the last known occupancy. Burrows > 11 cm with a clear tunnel within 800 m of occupied natal rearing dens should be protected from April 1 to August 31.

2) Shelter den

Any tunnel and connected chambers used by a Swift Fox for shelter from weather or escape from predators is considered a residence.

Physical appearance and context

Swift foxes often modify prairie burrows such as badger holes for use as shelter dens throughout the year2,3. However, they may use unmodified badger or similar sized holes as shelter dens as well7. Entrance holes for shelter dens may be smaller (≥ 11 cm diameter with a clear tunnel) than entrance holes for natal dens and typically shelter dens have fewer entrances than natal dens7,9. Opportunistic use of appropriate sized holes may occur during predator avoidance.

Function

Shelter dens serve as shelter from weather extremes and as escape refugia from predators. They are particularly important as refugia from predators during spring and fall dispersal and from weather extremes during the winter.

Damage and destruction of residence

Any alteration that destroys the function of shelter dens would constitute damage or destruction of the residence. This would include, but is not limited to, habitat change near the den, including ploughing or disturbing native short or mixed grassland communities, particularly when such changes lead to the blocking or abandonment of a den.

Period and frequency of occupancy

Any shelter den should be protected for 5 months from the time of last known occupancy. Occupancy can be determined from fox sightings, tracks, scats, prey remains, fresh digging or hair around the entrance.

Additional information

For more information on the Swift Fox

For more information on SARA

Recommended citation

Please cite this document as:

Government of Canada. Species at Risk Act Public Registry. Residence Descriptions. Description of residence for Swift Foxes (Vulpes velox) in Canada.

References

1 Allardyce, D., and M. A. Sovada. 2003. A review: ecology, historical distribution and status of Swift Foxes in North America. In M. Sovada and L. Carbyn, eds. Swift fox conservation in a changing world. Canadian Plains Research Center, University of Regina

2 Herrero S, Schroeder C, Scott-Brown M. 1986. Are Canadian foxes swift enough? Biological Conservation 36:159-167.

3 Pruss S.D. 1999. Selection of natal dens by the Swift Fox (Vulpes velox) on the Canadian prairies. Canadian Journal of Zoology 77:646-652.

4 Cutter, W.L. 1958. Denning of the Swift Fox in northern Texas. Journal of Mammalogy 39(1): 70 74.

5 Kilgore, D.L. Jr. 1969. An ecological study of the Swift Fox (Vulpes velox) in the Oklahoma panhandle. The American Midland Naturalist 81(2): 512 533.

6 Hillman, C.N., and J.C. Sharps. 1978. Return of Swift Fox to northern Great Plains. Proceedings of the South Dakota Academy of Science 57: 154 162.

7 Moehrenschlager, A. 2000. Effects of ecological and human factors on the behaviour and population dynamics of reintroduced Canadian Swift Foxes (Vulpes velox). Dissertation, University of Oxford, Oxford, United Kingdom.

8 Olson, T. L. 2000. Population characteristics, habitat selection patterns, and diet of Swift Foxes in southeast Wyoming. M. Sc. Thesis. University of Wyoming, Laramie. 139pp.

9 Pruss S.D. 1994. An observational natal den study of wild Swift Fox (Vulpes velox) on the Canadian Prairie. M.E.Des. Alberta, Canada. University of Calgary.

10 Tannerfeldt, M., Moehrenschlager, A., and A. Angerbjörn. 2003. Den ecology of swift, kit and arctic foxes: a review. In M. Sovada and L. Carbyn, eds. Swift fox conservation in a changing world. Canadian Plains Research Center, University of Regina.

11 Alberta Fish & Wildlife Division. 2001. Recommended Land Use Guidelines for Protection of Selected Wildlife Species and Habitat Within Grassland And Parkland Natural Regions of Alberta.

12 Environment Canada. 2009. Petroleum Industry Activity Guidelines for Wildlife Species at Risk in the Prairie and Northern Region. Canadian Wildlife Service, Environment Canada, Prairie and Northern Region, Edmonton Alberta. 64p.

13 Saskatchewan Environment and Resource Management. 2003. Saskatchewan Activity Restriction Guidelines for sensitive species in natural habitats.

14 Egoscue, H.J. 1962. Ecology and life history of the kit fox in Toole County, Utah. Ecology 43(3): 481 497.