The Cooke County, Illinois, Coyote Project provides some interesting research on observations of coyote attacks on dogs in the Chicago metropolitan area. Using a search of newspaper databases from 1990-2004, they found 70 articles of coyote attacks on dogs. The average number of attacks per year increased from 0-2/yr in 1990 up to 6-14/yr in 2005. Most attacks (60%) were on small breed dogs such as Yorkshire Terriers, Shih Tzus and Jack Russell Terriers, and these attacks were frequently fatal. Coyote attacks on dogs peaked in December – February during the coyote mating season and again during April when the pups are usually born (Gehrt 2010). They concluded that these patterns are consistent with resident, territorial coyote attacks rather than solitary individuals. Attacks on larger dogs usually involved two or more coyotes and were most likely to occur during the mating season, when coyotes are most territorial. In contrast, attacks on small dogs were likely to occur at any time of the year (Gehrt 2010). Gehrt and Riley (2010) conclude that this pattern indicates that these attacks result from competition as well as predation. In interspecific (between species) competition, larger carnivores such as wolves will opportunistically kill smaller carnivores such as coyotes and foxes.
Since these results are only from one location and were based on newspaper articles, some care should be taken in generalizing the results. For instance, the larger number of Yorkshire Terriers and Shih Tzus being attacked, does not necessarily mean that coyotes are more likely to attack these particular small breeds. There may just be more of these breeds present in the Chicago area.
I would also like to point out that none of these results were actually published in the scientific literature. In fact, I wasn’t able to find a single research study on coyotes attacking dogs, although I did (somewhat ironically) find one article published on dogs attacking a coyote. I compiled these results from the Cooke County, Illinois, Coyote Project website, their research bulletin (Gerht 2006), and from a brief summary of the results in Urban Carnivores (Gehrt and Riley 2010). However, in doing so, I did find some inconsistencies in the data. For example, the website (where I got most of my numbers) indicated that they found 70 attacks from 1990-2004, but Gehrt and Riley (2010) state that there were 60 attacks from 1990-2007 (obviously they can’t both be right). I also found that some of the percents in the breed pie chart (on the website) did not match the numbers in the text. Therefore, Table 1 & 2 are my best interpretation of what I found and may not be entirely accurate.
Gehrt, Stanley. 2006. Urban coyote ecology and management – The Cook County,Illinois coyote project. Ohio State University Extension Bulletin 929. 32 pp.
Gehrt, Stanley and Seth P.D. Riley. 2010. “Coyotes (Canis latrans)” in Urban Carnivores: Ecology, Conflict, and Conservation. Gehrt, Stanley, D., Seth P.D. Riley, and Brian L. Cypher, editors. The John Hopkins University Press.
Updated: January 11, 2014