August 2021 - 42

Swift fox observations in
Wyoming before and after 2010
NEW HOMES
By tapping into Game and Fish's Wildlife
Observation System, managed by the Wyoming
Natural Diversity Database, biologists can further
explore this novel expansion. The Wildlife Observation
System, or WOS, includes observation
records for all wildlife species in Wyoming. These
observations are submitted from wildlife and land
management agencies as well as wildlife researchers.
The WOS currently contains more than 1,400
observations of swift foxes, including detailed
information on location and date of observation.
Although swift foxes have been documented
outside their predicted historic range in Wyoming
as early as 1983, looking at a map of these
observations over time shows the population really
started expanding within the last decade. In fact,
swift foxes have now been documented in nearly
all grassland and sagebrush basins statewide. Game
and Fish has even confirmed swift foxes in some
unique areas, including one fox, likely a young
fox dispersing to a new location, at roughly 8,000
feet in the Absaroka Mountains just south of the
Montana line.
Historic Swift Fox Range
Swift fox photo locations
Swift fox observations before 2010
Swift fox observations after 2010
Swift fox observations have been increasing in western Wyoming with most occurring after 2010. (Map information provided
by Nyssa Whitford/WGFD)
swift foxes were never thought to be present in the
area, even historically. In the summer of 2016,
Game and Fish reintroduced ferrets to Meeteetse.
That first fall, biologists conducted multiple nights
of spotlight surveys. Although the survey teams
found many of the ferrets released earlier in the
year, they did not observe any swift foxes. However,
surveys in the fall of 2017 were a different
story when a few swift foxes were observed. By the
fall of 2018, swift fox sightings were a common
occurrence during the annual spotlighting efforts.
Reports of swift foxes outside their typical habitats
in western Wyoming have continued to roll
in from locations including Powell, Thermopolis,
Lander, Big Piney and Evanston. Thanks to the
increasing popularity and use of remote cameras
and always-available cell phone cameras, many
of these reports came with photographs. These
photographs were critical because they allowed
biologists to verify reports and, in some cases,
document kits. These kits confirmed swift foxes
were not only present in the western part of the
state, but they were successfully reproducing.
42 | August 2021
Although biologists are starting to tease out
when swift foxes started expanding into the western
part of the state, it is still a mystery why. Swift
foxes were once thought to be prairie specialists.
Throughout the rest of their range this still holds
true, but the Wyoming population has broken the
norm. Although research in the Shirley Basin area
in the late 1990s demonstrated swift foxes were
able to thrive in areas with at least some shrubs,
the sagebrush habitats in the western half of the
state are a far cry from the prairie habitats of the
Great Plains. If swift foxes were somehow unable
to survive in these sagebrush systems historically, it
seems plausible that some recent change has now
allowed them to overcome that barrier.
Common causes of death for swift foxes are
predation by coyotes and collisions with vehicles.
Although coyote control efforts do occur
throughout Wyoming, potentially benefiting swift
fox populations at a local level, efforts are usually
targeted and at a small scale. Therefore, it seems
unlikely they would have statewide effects on
swift foxes. Similarly, roadways and traffic have
likely not decreased in the past decade. Traffic has
likely increased, especially in the tourist-heavy
western part of the state. Many of the verified
observations of swift foxes throughout the state
are of road-killed animals.
One hypothesis is that perhaps swift foxes
were limited by other resources that may have
prevented expansion, such as food. Swift fox
observations throughout the western part of the
state overlapped with anecdotal observations

August 2021

Table of Contents for the Digital Edition of August 2021