Swift fox (Vulpes velox) COSEWIC assessment and status report 2009: chapter 11


Technical Summary

Vulpes velox

Swift Fox – Renard véloce

Range of occurrence in Canada (province/territory/ocean):
Alberta, Saskatchewan

Demographic Information

Generation time
At least 3 yrs
Is there an [observed, inferred, or projected]
continuing decline in number of mature individuals?
No
Estimated percent of continuing decline in total
number of mature individuals within [5 years
or 2 generations]
The number has remained stable over the last 5 yrs
[Observed, estimated, inferred, or suspected]
percent [reduction or increase] in total number
of mature individuals over the last [10 years,
or 3 generations].
There has been a 126% increase over the last 10 yrs
[Projected or suspected] percent [reduction
or increase] in total number of mature individuals
over the next [10 years, or 3 generations].
Unknown
[Observed, estimated, inferred, or suspected] percent
[reduction or increase] in total number of mature individuals over any [10 years, or 3 generations]
period, over a time period including both the past and the future.
Stable-increase
Are the causes of the decline clearly reversible and
understood and ceased?
No
Are there extreme fluctuations in number of mature
individuals?
No

Extent and Occupancy Information

Estimated extent of occurrence
21 544 km²
Index of area of occupancy (IAO)
Moehrenschlager and Moehrenschlager (2006) used townships rather than 2x2 grid to calculate AO.
6 343 km²
Is the total population severely fragmented?
No
Number of “locations*
For Swift Fox in Canada, disease is a “single threatening event” that can rapidly affect all individuals of the taxon present. This threat is real for Swift fox because: 1) high recorded seroprevalence of several viruses in the current population, 2) documented evidence of unpredictable disease outbreaks driving the near extirpation of many endangered canid populations worldwide, and 3) Swift Fox in Canada exist as one meta–population with evidence of long–range dispersal between sub–populations, and therefore one epidemiological unit. This meets the IUCN definition of 1 location.
1
Is there an [observed, inferred, or projected]
continuing decline in extent of occurrence?
No
Is there an [observed, inferred, or projected]
continuing decline in index of area of occupancy?
No
Is there an [observed, inferred, or projected]
continuing decline in number of populations?
No
Is there an [observed, inferred, or projected]
continuing decline in number of locations?
No
Is there an [observed, inferred, or projected]
continuing decline in [area, extent and/or quality]
of habitat?
Yes, although extent of impact is unknown
Are there extreme fluctuations in number of
populations?
No
Are there extreme fluctuations in number of
locations*?
No
Are there extreme fluctuations in extent of
occurrence?
No
Are there extreme fluctuations in index of area of occupancy?
No

*  See definition of location.

Number of Mature Individuals (in each population)

Population
N Mature Individuals
Border (Alberta, Saskatchewan) (general approximation – mature proportion unknown)
513 (estimated)
GNP (Saskatchewan) (general approximation – mature proportion unknown)
134 (estimated)
Total
647

Quantitative Analysis

Probability of extinction in the wild is at least [20% within 20 years or 5 generations, or 10% within 100 years].
N/A

Threats (actual or imminent, to populations or habitats)

  • Predation (Coyotes)
  • Habitat alteration (conversion to agriculture, energy development, roads, climate change)
  • Disease
  • Poisoning
  • Trapping
  • Road mortality
  • Interspecific competition (Coyotes, Red Foxes)

Rescue Effect (immigration from an outside source)

Montana (USA):
Vulnerable; population is increasing
Is immigration known or possible?
Yes
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
Rescue is likely from Montana only, but not from core Swift Fox range in the U.S.
to a limited extent

Current Status

COSEWIC:
Threatened (November 2009)
Alberta:
Endangered
Saskatchewan:
Endangered
IUCN Red List of Threatened Species:
Least Concern

Status and Reasons for Designation

Status:
Threatened
Alpha-numeric code:
D1+2

Reasons 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 COSEWICassessment 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.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals):
Not applicable. The current Canadian population(s) increased after reintroductions. There is no indication that the total number of mature individuals has declined over the last 10 years/3 generations, or might do so in the next 10 years/3 generations.

Criterion B (Small Distribution Range and Decline or Fluctuation):
Not applicable. While the extent of occurrence hovers at about the threshold for Threatened under criterion B1 (21 544 km²), there is no clear fit for the accompanying conditions that must be met. Swift Fox population(s) in Canada do not undergo extreme fluctuations and although there is continued habitat decline in the region, the extent to which this is having or will have an impact on current Swift Fox range and population status is unknown.

Criterion C (Small and Declining Number of Mature Individuals):
Not applicable. There is no indication of a declining number of mature individuals

Criterion D (Very Small Population or Restricted Distribution):
Meets Threatened D1+2. D1: current population estimate for mature individuals for Swift Fox is 647, which places it well above 250 (Endangered) but below the 1000 threshold for Threatened. D2: Swift Fox in Canada are in one connected location, and subject to the possibility of one threatening event, disease, affecting all members of the species. They therefore qualify as Threatened under this criterion.

Criterion E (Quantitative Analysis):
Not applicable. There is no population projection suggesting that the probability of extinction of the species in the wild is > 10% (100 yrs) or > 20% (20 years/5 generations).

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