We simultaneously studied raccoon (Procyon lotor) populations inhabiting urban, suburban, and rural open areas in northeastern Illinois, USA, to examine the effects of urbanization on raccoon demographics. We predicted that raccoon density was higher in urbanized than rural landscapes because of increased survival and reproduction rates and greater site fidelity in urbanized areas. Density estimates for both the urban and suburban sites were greater (P < 0.001) than for the rural site during all seasons. Density estimates for the urban and suburban sites were similar (0.177 ? P< 0.603) during 4 of 6 seasons. Percentages of parous females were similar among sites. However, higher proportions of juveniles to adult females captured at the urbanized sites may indicate larger litter sizes. Adult female survival was highest at the urban site during the first 2 years, but dropped due to an unknown disease during the final year. Urban raccoons experienced the fewest mortality sources, whereas rural raccoons experienced the most. Disease was the greatest mortality factor at the urban site, while vehicle-related mortalities dominated at the suburban and rural sites. The high ratio of marked to unmarked raccoons captured may indicate greater site fidelity at urbanized sites. Our data suggest that multiple factors, including increased survival, higher annual recruitment, and increased site fidelity, are jointly responsible for high-density raccoon populations in urbanized areas. Direct management of raccoon numbers in urbanized areas likely will require continuous control measures, because raccoons are capable of quickly repopulating an area after the resident population has been reduced. The most effective control measure may be the reduction of anthropogenic food sources that support raccoons at high densities.

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The frequency of interactions among individuals is vital to understanding many aspects of a species' behavioral ecology. This also is a fundamental aspect of infectious disease epidemiology. However, the number of times an individual animal comes into contact with another is an extremely difficult parameter to estimate. This paper describes radiocollars (proximity detectors) capable of recording close contacts among radiocollared individuals. We conducted laboratory tests using collars alone (i.e., not fitted on an organism) and field tests of collar performance with collars fitted on 42 free-ranging raccoons (Procyon lotor) within a 20-ha portion of the Ned Brown Forest Preserve in northeastern Illinois, USA. During laboratory tests, we determined variation in detection distance within and among collars, effect of collar orientation on detection distances, and accuracy of recorded duration of proximity and identification of contacted collar. Overall variation in detection distance both within and among collars was relatively low, although we observed intrinsic variation in collar strength. We found little variation in horizontal detection distances with collar orientation, although mean distances for vertical tests were greater than most horizontal means. Recorded contact duration deviated from actual time by 3 seconds for short-duration (10-300 sec), and by 30 seconds for extended-duration (8-14 hr) contacts recorded as a single event. However, there was a tendency for the collars to record extended-duration contacts as multiple events, with the frequency dependent on settings. Identification number of the contacted collar was correctly identified in all cases (n ¼ 1,537). We downloaded 35 of the 42 proximity detectors deployed on free-ranging raccoons. Of these, approximately 57% were functioning properly, 9% exhibited problems apparently correctable in the field, and 34% exhibited problems not correctable in the field. For random pairs of raccoons, daily contact duration and number of contacts (omitting 1-sec contacts) recorded by both detectors did not differ (P ! 0.066). Overall, collars produced accurate information in terms of detection range, duration of contact, and contacted collar identification, and represented a promising improvement over previous methods to assess intraspecific contact rates of secretive, nocturnal, or otherwise unobservable species. Because accurate determination of contact rates requires that a population be saturated with detectors, their use may be most appropriate for species readily trapped. (WILDLIFE SOCIETY BULLETIN 34(5):1333-1344 2006)

Coyotes (Canis latrans) are an opportunistic predator that have adapted to many human-modified environments. Conflicts between coyotes and humans are an increasing concern for managers in urban areas. We examined the spatial and temporal utilization and availability of natural and human-associated food for coyotes in the Chicago metropolitan area, Illinois, USA. We collected 1429 coyote scats from May 2000 to December 2002, and conducted prey surveys in 2002, in 4 sites that varied in their degree of urban development. Dominant food items included small rodents, white-tailed deer (Odocoileus virginianus), fruit, eastern cottontail (Sylvilagus floridanus) and birds. Their availability and occurrence in scats varied among sites and seasons. The occurrence of human-associated food items, which was only found in significant amounts in the most developed site, varied seasonally (2-25%). Because coyotes in less-developed areas had lower dietary diversity, these coyotes may have to venture into developed areas when there is a decline in the abundance of major prey species for that specific area.

With increasing urbanization, some animals are adapting to human-dominated systems, offering unique opportunities to study individual adaptation to novel environments. One hypothesis for why some wildlife succeed in urban areas is that they are subsidized with anthropogenic food. Here, we combine individual-level movement patterns with diet composition based on stable isotope analysis to assess the degree to which a rapidly growing population of coyotes (Canis latrans) in Chicago consumes anthropogenic resources. We used telemetry to classify coyotes into three groups based on social class and home range composition: (1) residents with home ranges in urban nature preserves; (2) residents with home ranges that had a high proportion of urban land; and (3) transients that had relatively large home ranges and variable use of urban land. We found that natural and anthropogenic resources in this system can be reliably partitioned with carbon isotopes. Mixing models revealed that resident coyotes associated with most urban nature preserves consumed trace to minimal amounts of anthropogenic resources, while coyotes that live in the urban matrix consume moderate (30-50%) to high (>50%) proportions of anthropogenic resources. Lastly, we found evidence of prey switching between natural and anthropogenic resources and a high degree of inter-individual variation in diet among coyotes. In contrast to the expectation that urban adaptation may dampen ecological variation, our results suggest individuality in movement and diet exemplifies the successful establishment of coyotes in urban Chicago. Our study also suggests that direct anthropogenic food subsidization is not a prerequisite for successful adaptation to urban environments.

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