1Department of Anthropology, University of Texas-Austin, 2Section of Integrative Biology, University of Texas-Austin
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Host sociality is an important predictor of parasite risk because parasite transmission can increase when host individuals spend more time in contact with conspecifics. Group size and association patterns have been shown to influence parasite loads by affecting the frequency of intraspecific contacts. We examined the relationship between within-group social patterns and ectoparasite dynamics in Verreaux’s sifaka (Propithecus verreauxi), a gregarious folivore, in the Kirindy Mitea National Park of Madagascar. Ectoparasite counts (e.g., lice, Trichophyloterus babakotus) were collected opportunistically for 32 individuals during annual captures between 2006 and 2010. Over 1300 hours of contact and grooming data were collected using focal animal sampling for 20 individuals from January 2007 to December 2008. We used these data to assess the influence of demography and social behavior on ectoparasite loads for Verreaux’s sifaka in five social groups (range=3-11 individuals). Ectoparasite load was positively correlated with social group size. Males, in general, had higher ectoparasite counts than females. The number of within-group contacts exhibited a significant positive relationship with ectoparasite loads, but only for females. Ectoparasite loads, however, were not correlated with the rate at which sifaka received grooming. Before and after data were available for three males who transferred social groups and all three males had higher ectoparasite loads after dispersing. Sex differences in sifaka ectoparasite loads most likely arise from behavioral patterns, such as female dominance and male-biased dispersal. Our results suggest that contact networks influence ectoparasite transmission in Verreaux’s sifaka.
This study was funded by NSF Grant DEB-0749097 to L.A. Meyers.