The Cook County, Illinois, Coyote Project



  Coyote Mortality  



  • Causes of Mortality in Cook County

  • The Oldest Coyote in Cook County



Most coyotes die before reaching their second year. This is because many pups die from a variety of causes during their first few months outside the den. Survival is fairly consistent among seasons, even during the winter. The oldest coyote in our study was an eleven-year-old alpha female, Big Mama.  More than 70 coyotes have died during the eight-year study.

We have found that the survival rates of adult coyotes in the Chicago metropolitan area are similar to estimates for coyotes living in rural Illinois. However, the survival rates of juvenile coyotes in Cook County are approximately five times higher than the 13% survival rate reported for rural juvenile coyotes. 

Rural Illinois is dominated by row-crop agriculture and hunting of coyotes occurs year-round without any regulatory constraints, such as bag limits.  Given this intensive hunting and trapping pressure found in rural Illinois, coyote vulnerability is magnified during parts of the year in which substantial cover/shelter (e.g. agricultural crops) is lost due to crop harvesting.  Large metropolitan areas, on the other hand, provide more year-round protection since there is no seasonal loss of habitat via crop harvesting and a lack intensive hunting and trapping pressure.

By far the most frequent cause of death for urban coyotes has been collisions with vehicles (50 to 70 percent of deaths each year).

Other causes of death have included:

  • Shootings;

  • Malnutrition; and

  • Disease, such as sarcoptic mange and parvo virus (in Cook County, four coyotes died from unknown causes). 

    Mange has been the most common disease-related mortality, and all cases occurred post-2003.  See Disease for more information.


Figure 1 below summarizes the causes of mortality for radio-collared coyotes in Cook County between 2000 and 2005.  Mange-related deaths only occurred during 2004-2005.

 Fig. 1.-- Frequency distribution for causes of mortality for radio-collared coyotes in Cook County, IL, 2000-2005



Few of the diseases we documented in coyotes are of major importance for people or pets.  Mange was the most common disease to affect survival in coyotes.

There are different types of mange with a range of severity among wildlife species. 

The type of mange usually associated with coyotes is Sarcoptic Mange.



Some Facts About Sarcoptic Mange:

         Mange is caused by a very small mite.

         The mite burrows into the skin and lays eggs.

         Severe cases of infection will result in hair loss and wounds from scratching.

         It is transmitted from one animal to another by contact or sharing dens.

         It can spread to pets, but that rarely happens, especially with coyotes.

         Mange mites are rarely a problem for humans.

Coyote-strain rabies is restricted to southern Texas, but coyotes are sometimes infected with rabies from other species. If a person is bitten by a coyote that is acting aggressive, he or she should be treated for rabies as a precaution. Anytime a person is bitten by a coyote, animal care and human health professionals should be contacted.

Urban coyotes may serve as a reservoir for heart worm; about one-third of the Chicago-area coyotes were infected with the parasite.

See Disease for more on this topic.



Big Mama died in 2010 at age 11. See Our Packs to learn more about Big Mama.


Big Mama, age 6.






The Cook County, Illinois, Coyote Project

The Ohio State University