The dynamics of sarcoptic mange in an urban coyote (Canis latrans) population
Evan C. Wilson, MS
Advisor: Stanley D. Gehrt
Coyotes (Canis latrans) are the top predator in the metropolitan Chicago area, and other urban areas of North America. As such, coyotes play an important role in the dynamics of the urban ecosystem. Coyotes have increasingly come into conflict with humans as both human and coyote populations have increased in the areas surrounding major cities. Sarcoptic mange is an important disease of coyotes throughout their range, and is capable of epizootics with high prevalence and mortality rates. My objectives were to examine the dynamics of sarcoptic mange in an urban coyote population, determine the effects of changes in mange prevalence on coyote population dynamics and determine whether mange infection resulted in altered habitat selection and use.
Coyotes were trapped and radio-collared during 2000 - 2011. Individuals were examined for signs of sarcoptic mange at the time of capture. Visual observations of individuals being radio-tracked meant that animals that had developed signs of sarcoptic mange could be identified based on hair loss patterns after capture.
Three hundred ten coyotes were examined for signs of sarcoptic mange during the course of the study and 49 (16%) were diagnosed with sarcoptic mange at some point. Sarcoptic mange incidence remained relatively steady in the study population throughout the study, implying that mange infection during this time period was enzootic. The majority of mortalities due to sarcoptic mange occurred during the winter (December – January). There was no evidence that changes in the prevalence of sarcoptic mange had any effect on annual survival rates, nor was there any relationship between annual survival and mange-specific mortality rates. Coyotes with sarcoptic mange showed a significantly higher mean percentage of locations in medium-density urban areas during the period spanning 60 days prior to death.
Sarcoptic mange is currently enzootic in the Chicago metropolitan area. This does not preclude epizootics in the future, as sarcoptic mange has been documented in the literature to remain enzootic in a population and until eventually erupting in an epizootic over a larger area at a later date. I found no evidence that mortality due to mange was additive or compensatory with other forms of mortality in the population. At the current time, sarcoptic mange does not seem the occur in high enough prevalence to have a major impact on coyote populations in this area, although it is an important cause of mortality in the system and may have impacts on coyote abundance at a local scale. Additionally, sarcoptic mange appears to affect the behavior of heavily infected individuals which may contribute to human-coyote conflict. The combination of increased mortality during winter months and increased residential habitat use prior to mortality may be an important factor in human-coyote conflict in the Chicago metropolitan region and other urban areas with enzootic mange and cold winters.
Information on the factors that contribute to coyote mortality in urban systems can increase our knowledge about the factors which regulate coyote populations in urban areas, increasing our ability to effectively manage coyote populations. Understanding reasons why human-coyote conflicts take place can not only inform management decisions on how to handle conflicts, but educating the public about causes of conflict can prevent conflicts from occurring in the first place.