Raccoons (Procyon lotor) frequently establish defecation sites, termed latrines, on large logs, stumps, rocks, and other horizontally oriented structures/surfaces. These latrines are important foci of infective eggs of Baylisascaris procyonis, a nematode parasite of raccoons which is pathogenic to numerous species of mammals and birds. To examine the role of raccoon latrines in this animal-parasite interaction, we documented animal visitations to raccoon latrines in two large forested tracts and two woodlots in Indiana (USA) during 1994 and 1995. Species richness of vertebrate visitors did not differ between sites or years, but species composition differed by site and year. Fourteen mammal and 15 bird species were documented visiting raccoon latrines. Small granivorous mammals, including white-footed mice (Peromyscus leucopus), eastern chipmunks (Tamias striatus), and tree squirrels (Sciurus carolinensis, S. niger, Tamiasciurus hudsonicus) were the most common visitors to latrine sites. White-footed mice, chipmunks, white-breasted nuthatches (Sitta carolinensis), and opossums (Didelphis virginiana) were photographed foraging on undigested seeds in raccoon feces. Active foraging at latrines also was shown experimentally; seeds embedded in raccoon feces were removed at a greater rate at latrine sites than at nonlatrines. We conclude that raccoon latrines are visited routinely by a variety of vertebrates, especially small granivorous rodents and birds which forage for seeds in raccoon feces, and that raccoon latrines are probable sites of transmission of B. procyonis to susceptible mammals and birds.

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Raccoons (Procyon lotor) habitually defecate at preferred sites (latrines). Feces at latrines often harbor eggs of the roundworm Baylisascaris procyonis, a parasite of raccoons that is pathogenic to numerous species of small vertebrates. Undigested seeds are also commonly found in raccoon feces, the composition varying with availability of seed types. Thus, feces at latrines may serve as a source of food and pose a mortality risk for small granivores. To examine this interaction, we manipulated the seed composition in feces at simulated raccoon latrines and tested for differences in vertebrate visitation rates as a function of seed type. Treatments involved placing seeds, including corn, cherry (Prunus virginiana), dogwood (Cornus racemosa), and a combination of the three types, at simulated raccoon latrines. Using Trailmaster ™ camera systems we documented 2406 vertebrate visits by 16 mammal and 11 bird species during 455 camera-nights. Small granivorous mammals, including white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus), were the most common visitors. Visitation by white-footed mice was significantly greater when corn, the most preferred seed type, was present in raccoon feces. Visitation by eastern chipmunks and other vertebrate species did not vary with seed type. Active foraging was documented for five vertebrate species and accounted for 10% of all recorded events. We conclude that raccoon latrines are routinely visited by a variety of vertebrate species, especially small granivores. Active foraging for seeds in raccoon feces is an important risk factor for transmission of B. procyonis to small vertebrates, and white-footed mice may suffer elevated rates of infection when corn is present in raccoon feces.Résumé : Les ratons-laveurs (Procyon lotor) ont habituellement des sites de préférence pour déposer leurs défécations (latrines). Les fèces recueillies dans ces latrines contiennent souvent des oeufs de Baylisascaris procyonis, un ver rond parasite des ratons-laveurs, qui a des effets pathogènes chez de nombreuses espèces de petits vertébrés. On trouve aussi dans les fèces des graines non digérées dont la composition varie selon leur disponibilité saisonnière. Les fèces trouvées dans les latrines peuvent aussi servir de source de nourriture et comportent un risque de mortalité pour les petits granivores. Pour étudier cette interaction, nous avons manipulé la composition du stock de graines dans les fèces à des latrines simulées de raton-laveur et examiné les variations des visites des vertébrés en fonction des types de graines. Nous avons procédé à différents traitements, graines de maïs, de cerisier (Prunus virginiana), de cornouiller (Cornus racemosa) et une combinaison de graines, dans des latrines simulées. Au moyen de systèmes de caméras Trailmaster TM , nous avons enregistré 2406 visites de vertébrés appartenant à 16 espèces de mammifères et 11 espèces d'oiseaux en 455 nuits-caméras. Les petits mammifères granivores, dont la Souris à pattes blanches (Peromyscus leucopus)...

2001. Changes in transmission of Baylisascaris procyonis to intermediate hosts as a function of spatial scale. -Oikos 93: 213-220.Physical changes in landscapes alter the abundance and distribution of species. Higher-order effects can occur when changes in ecological processes result in altered interspecific interactions and subsequent changes in a species' abundance or persistence. Baylisascaris procyonis, a roundworm parasite of raccoons (Procyon lotor), is pathogenic to numerous small vertebrates that serve as intermediate hosts, including white-footed mice (Peromyscus leucopus). Raccoons have responded positively to agriculturally induced changes in landscapes, with potential consequences for intermediate hosts of B. procyonis. We examined white-footed mice from a homogeneous, predominantly forested landscape in south-central Indiana and a heterogeneous, predominantly agricultural landscape in northwestern Indiana for presence of larval B. procyonis. We compared prevalence of infection, intensity of infection, and average number of larvae per mouse between the landscapes, and among forest patches within the highly fragmented agricultural landscape. Prevalence, intensity of infection, and average number of larvae were significantly higher in the highly fragmented landscape. Within the agricultural landscape, regression models predicted probability of infection, intensity of infection, and average number of larvae per mouse per patch as functions of forest patch area and isolation. We conclude that positive responses of raccoons to agriculturally induced fragmentation of forests have resulted in increased encounter rates between white-footed mice and infective stages of B. procyonis between and within landscapes, resulting in increased transmission of the parasite to intermediate hosts.

The raccoon (Procyon lotor) is the definitive host of Baylisascaris procyonis, a large intestinal roundworm. The prevalence of infection among raccoon populations often is high, and in the midwestern United States B. procyonis is documented in 68–82% of raccoons. Because raccoon populations appear to be increasing in response to changes in human land use and because B. procyonis is considered an emerging zoonotic disease, it is important to determine reliable methods to monitor prevalence of infection among raccoons. We compared the relative sensitivity of 3 common methods used by wildlife biologists to determine prevalence in free‐ranging raccoon populations. We determined prevalence of infection among midwestern raccoon populations from 456 raccoon fecal samples, 742 raccoon latrine samples, and 212 necropsies (gut analysis). We developed logistic regression models in order to predict the log likelihood of presence of B. procyonis in a given sample as a function of season, land use, and technique. Finally, we measured the sensitivity of fecal sampling by evaluating fecal samples taken from 72 necropsies for the presence of B. procyonis eggs. Necropsy analysis yielded the highest measure of prevalence (44%), followed by latrine samples (22.5%), and fecal samples (17.5%). Necropsy analysis explained the most variance in logistic models, suggesting that this is the most reliable method. However, this technique is labor‐intensive and may not be the most efficient method for large‐scale investigations of B. procyonis prevalence. Fecal analysis is a reliable method of determining prevalence among raccoons as we observed B. procyonis eggs in 66% of fecal samples taken from positive necropsies. Latrine sampling may be the most efficient method and perhaps the best estimator of zoonotic potential; however, wildlife managers should realize that this measure often is an underestimate of prevalence among raccoons and develop management plans accordingly.