Raccoons (Procyon lotor), like most carnivores, are nocturnal and secretive and consequently difficult to observe. We used proximity-detecting collars to determine effects of sex, age, and season on contact rate and duration; document patterns of seasonal contact rates by dyad type and determine whether patterns were random; identify dyads that exhibited contact rates significantly greater than expected and document the persistence of these positive associations across seasons; and document frequency of den sharing as an additional measure of positive associations at an urban study site with a high-density raccoon population. Contact rate and duration were affected by dyad type, season, and their interaction. Male-male (MM) dyads exhibited higher contact values than male-female (MF) or female-female (FF) dyads, and contact parameters were greater during winter and spring than summer and autumn. Contact parameters for MM and FF dyads were not affected by age of dyad members, whereas those of MF dyads were affected by age and its interaction with season. MF dyads with older individuals exhibited greater contact parameters, and this effect was greatest during winter. For all dyad types and seasons, except FF dyads during winter, observed distributions of contact rates differed from expected. Males formed groups, with most positively associated dyads persisting across seasons, and females were associated almost exclusively with members of only 1 male group. Some positively associated MF dyads occurred during autumn and continued through spring. Positively associated FF dyads occurred at a lower rate and were ephemeral, seldom lasting more than 1 season. FF and MF dyads exhibited a greater proportion of low-frequency contacts with conspecifics than expected during all seasons, except winter, which may function to maintain amicable relationships between neighbors or reinforce dominance hierarchies and create a framework for more complex social behaviors. Raccoons appear to live in a fission-fusion society, with many short-term acquaintances and a few long-term associations.

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Raccoons are an important vector of rabies and other pathogens. The degree to which these pathogens can spread through a raccoon population should be closely linked to association rates between individual raccoons. Most studies of raccoon sociality have found patterns consistent with low levels of social connectivity within populations, thus the likelihood of direct pathogen transmission between raccoons is theoretically low. We used proximity detecting collars and social network metrics to calculate the degree of social connectivity in an urban raccoon population for purposes of estimating potential pathogen spread. In contrast to previous assumptions, raccoon social association networks were highly connected, and all individuals were connected to one large social network during 15 out of 18 months of study. However, these metrics may overestimate the potential for a pathogen to spread through a population, as many of the social connections were based on relatively short contact periods. To more closely reflect varying probabilities of pathogen spread, we censored the raccoon social networks based on the total amount of time spent in close proximity between two individuals per month. As this time criteria for censoring the social networks increased from one to thirty minutes, corresponding measures of network connectivity declined. These findings demonstrate that raccoon populations are much more tightly connected than would have been predicted based on previous studies, but also point out that additional research is needed to calculate more precise transmission probabilities by infected individuals, and determine how disease infection changes normal social behaviors.

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Mammals often use latrine sites for defecation, yet little is known about patterns of latrine use in many common species such as raccoons (Procyon lotor). Because raccoon latrines are important foci for the transmission of raccoon roundworm (Baylisascaris procyonis), documenting metrics of raccoon latrine use may have public health implications. Although some studies have provided evidence that multiple raccoons visit single latrine sites, exact latrine visitation patterns of raccoons have never been documented. We monitored raccoon latrine usage using proximity-logging collars placed at 15 latrine sites. We found that latrine sites were visited by multiple raccoons (range 1-7), and raccoons visited as many as six latrines during a 2-wk period. No sex differences were found in the number of latrines visited or time spent during visits. We posit that the use of multiple latrine sites by raccoons may lead to the pattern that rates of B. procyonis infection at latrines are greater than infection rates found in individual raccoon fecal samples. This in turn could lead to greater transmission of B. procyonis to paratenic hosts. Our results support the conclusion that raccoon latrines can be major foci for the infection and spread of B. procyonis.