Seasonal survival and cause-specific mortality of urban and rural striped skunks in the absence of rabies

Abstract

Identifying factors that are limiting to populations is fundamental to understanding population dynamics of wildlife, and such knowledge is important for conservation and management. I compared survival and cause-specific mortality patterns between urban and rural populations of striped skunks (Mephitis mephitis) in northeastern Illinois. Rabies, an important mortality factor for skunks, was absent from the study populations. Body weights of skunks declined during winter in both areas, but there was a slightly greater decline for rural skunks. Estimates of annual survival were similar (P > 0.1) between areas, as were seasonal patterns of survival. Disease or poor physical condition was the greatest cause of mortality at the urban site throughout the year, whereas it was the most common mortality factor at the rural site only during winter and spring; vehicle collision was the most common cause of death at the rural site during summer and autumn. I found little evidence that body weight or condition before winter denning, sex, or age were related to survival during winter; however, relationships between these covariates and survival may have been obfuscated by parasites. Results from this study suggest that the winter season is a critical period for survival for skunks from rural and urban areas at temperate climates, anthropogenic factors associated with urban landscapes have minimal effects on skunk survival distributions, and disease is a major cause of mortality even in the absence of rabies. © 2005 American Society of Mammalogists.