March 2021 - 23

Swift fox

Swift foxes prey on small mammals and
birds. In the summer they also eat insects
and bird eggs. (Photo by Greg Bergquist)

The swift fox is Wyoming's smallest member of
the dog family. Adults weigh only 4 to 6 pounds. It is
easily distinguished from the red fox by its black tip of
the tail. It occupies shrub-steppe, but especially shortgrass prairie habitats. Forty years ago, the species was
thought to be uncommon and limited in distribution in
Wyoming, but reports from the public combined with
surveys by Game and Fish biologists have completely
changed understanding of the conservation status of
this species.
In the early 2000s, reports arrived of swift foxes from
wider areas of Wyoming than had been known. Animals
were found dead on highways in the western part of
the state, and game cameras captured their images in
far-flung locales. Nichole Bjornlie, Game and Fish
nongame mammal biologist based in Lander, described
her program's efforts to track the spread of swift foxes.
" Our first statewide survey in 2010 involved setting
remote cameras at 95 locations, with five cameras at
each location, and each camera aimed at a scent lure
for five nights. We found swift foxes across the eastern
two-thirds of the state, " she said.
Then something remarkable happened. Reports
from the public started coming from the western third
of the state.
" We had credible observations or carcasses from near
Big Piney, Worland and a pair of foxes from Evanston.
And these were not just lone dispersers; we received
reports of active dens near Lovell, Farson and Wamsutter. The most remarkable one was from alpine tundra
on Beartooth Pass, " Bjornlie said.
For some reason, a fox species thought to be a shortgrass prairie specialist was traversing long stretches
of big sagebrush, and climbing mountains through
coniferous forest.
What would cause such an abrupt and major change
in the distribution of swift foxes? Bjornlie explained
the major sources of swift fox deaths are attacks by
coyotes and vehicle collisions. Neither of these factors
are likely to have changed over a period of a few years.
She suspects bottom-up factors are more likely. Small
mammal numbers seemed to spike in the state over
the period of the range expansion, which could have
allowed the foxes to survive in more kinds of habitat
than before, although why swift foxes were absent from
these areas before European settlement is not clear.
The similar kit fox occurs in Colorado not far from
the southern border of Wyoming. With continued
climatic warming, it could extend its range northward
to the Cowboy State. Kit foxes are similar enough to
swift foxes that only an experienced eye or a DNA test
can distinguish them, and hybrids are known to occur.
The recent geographic range expansion of the swift fox
is great news for conservation and illustrates the value
of the public reporting unusual wildlife observations
to wildlife agencies.

Wyoming Wildlife | 23


March 2021

Table of Contents for the Digital Edition of March 2021

From the Director
In this issue
A couple pennies
Opening shot
Ask Game and Fish
Project profiles
Case files
In the field
Tracking the rarest carnivores
Seeking the slam
A family matter
Getting kids outside
Wild country dispatch
March 2021 - Cover
March 2021 - From the Director
March 2021 - In this issue
March 2021 - A couple pennies
March 2021 - Mailbag
March 2021 - Opening shot
March 2021 - 7
March 2021 - News
March 2021 - 9
March 2021 - 10
March 2021 - 11
March 2021 - Ask Game and Fish
March 2021 - Project profiles
March 2021 - Case files
March 2021 - 15
March 2021 - In the field
March 2021 - 17
March 2021 - Tracking the rarest carnivores
March 2021 - 19
March 2021 - 20
March 2021 - 21
March 2021 - 22
March 2021 - 23
March 2021 - 24
March 2021 - 25
March 2021 - Seeking the slam
March 2021 - 27
March 2021 - 28
March 2021 - 29
March 2021 - 30
March 2021 - 31
March 2021 - A family matter
March 2021 - 33
March 2021 - 34
March 2021 - 35
March 2021 - 36
March 2021 - 37
March 2021 - Getting kids outside
March 2021 - 39
March 2021 - 40
March 2021 - 41
March 2021 - 42
March 2021 - 43
March 2021 - 44
March 2021 - 45
March 2021 - Wild country dispatch
March 2021 - 47
March 2021 - Backpage