EMERGING FACTORS ASSOCIATED WITH THE DECLINE OF A GRAY FOX
POPULATION AND MULTI-SCALE LAND COVER ASSOCIATIONS OF
MESOPREDATORS IN THE CHICAGO METROPOLITAN AREA
A Thesis
Presented in Partial Fulfillment of the Requirements for
the Degree Master of Science in the
Graduate School of the Ohio State University
By
Alison N. Willingham, B.S.
*****
The Ohio State University
2008
Intraguild Competition with Coyotes
Coyote populations throughout North America are expanding, perhaps originally
due to the extirpation of wolves (Smith et al. 2003) and most recently due to increases in
agricultural land use (Patterson and Messier 2001). Agricultural fields may support
greater densities of prey species such as deer, rabbits and mice, as well as provide
abundant seasonal food in the form of crops.
Patterson and Messier (2001) found a
positive correlation between coyote and prey abundance, suggesting that these areas may
serve as high quality habitat for this behaviorally plastic carniserve as high quality habitat for this behaviorally plastic carnivore. In Illinois,
approximately 81% of the land is used for agricultural practices with 50% of that
consisting of row crops (Rosenblatt et al. 1999). This shift in land use may be providing
an abundant food source supporting increasing coyote populations. Most recently,
coyotes have moved into urban areas (Gompper 2002), likely in response to the diversity
and abundance of prey items and anthropogenic resources (Fedriani et al. 2001, Morey et
al. 2007).
A gradient of intraguild competition has been reported between coyotes and gray
foxes, as well as between coyotes and other species of fox. Some studies suggest that
gray foxes may be well equipped to coexist with coyotes, primarily due to their
omnivorous food habits, evasive tree-climbing behavior and seclusive nature (Sheldon
1949, Cypher 1993). Chamberlain and Leopold (2005) found that coyotes did not limit
the distribution of gray foxes, as several were found living entirely within coyote home
ranges; although foxes did avoid the core use areas of these territories. Gray foxes in
California were found to use space in a way that was more influenced by resource
distribution than by coyote distribution (Neale and Sacks 2001).
Other studies have documented negative relationships between coyotes and foxes
(Sargeant et al. 1987, Crooks and Soule 1999, Fedriani et al. 2000). In one study, 92% of
all gray fox mortalities were attributed to larger predators, with 67% of those mortalities
caused by coyotes (Farias et al. 2005). A kit fox (Vulpes macrotis) study determined that
coyote predation accounted for 75.8 ± 7.7% of mortality (Cypher and Spencer 1998)
Discussion
Are foxes going the way of porcupines? I can’t even remember the last time we saw one of those wonderful fellows!
Alan B. Sargeant & Stephen H. Allen
1989