Altered parasite assemblages in raccoons in response to manipulated resource availability
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The role that host aggregation plays in structuring parasite assemblages was examined by experimentally increasing the contact rates of raccoons, Procyon lotor. Two populations of raccoons in southern New York were monitored for 2 years to determine baseline levels of host interaction and to identify the parasite assemblage. In the third year of the study, one population was provisioned with the addition of clumped food resources, while the other was provisioned with equal quantities of dispersed food resources. Remote photography showed that raccoons aggregated at clumped resources but not at dispersed resources, and therefore contact rates between individuals were higher in the site with clumped resources. There were no differences in parasitism between the sites prior to resource augmentation. Among ectoparasites, there were no significant changes in the prevalence or abundance of any species in response to the perturbation. In contrast, across the endoparasite assemblage within and across hosts, the prevalence of infection increased as a result of increased host contact. Strong increases in the prevalence of a few directly transmitted species and slight increases among most species lead to increased evenness in parasite prevalence, suggesting that parasites in this system are transmission limited. In addition, the number of parasite species per host (the parasite infracommunity) was higher in the clumped-resource population. These endoparasite results suggest that intraspecific variation in the species richness of parasite communities of individual hosts, and the prevalence of parasitic species in host populations as assessed across entire parasitic assemblages, is robustly influenced by intraspecific variation in the degree of host contact. Further, these results suggest that anthropogenic changes which alter resource availability may have important consequences for disease transmission in wildlife.
KeywordsCommunity structure Resource manipulation Contact rates Disease transmission Baylisascaris procyonis
This work benefited from the aid of C. Fiorello, R. Goodman, H. Fener, P. Macchia, K. McFadden, C. Scully, R. Kays, W. Schuster, J.C. Morales, J. Brady, B. Brady, M. Munson, and P. Miller. Insights from Dr. S. Wade and the Cornell University Veterinary Diagnostic Laboratory were critical for parasite identification. Research was supported by the Black Rock Forest Consortium, AMNH Theodore Roosevelt Memorial Fund, and NSF (DEB-0347609). All research was approved by the New York State Department of Environmental Conservation and Columbia University (IACUC protocol no. 343).
- Allan SA (2001) Ticks (Class Arachnida: Order Acarina). In: Samuel WM, Pybus MJ, Kocan AA (eds) Parasitic diseases of wild mammals, 2nd edn. Iowa State Press, Ames Iowa, pp 72–106Google Scholar
- Anderson RM, May RM (1991) Infectious diseases of humans: dynamics and control. Oxford University Press, OxfordGoogle Scholar
- Barclay RM (1988) Variation in the costs, benefits, and frequency of nest reuse by barn swallows (Hirundo rustica). Auk 105:53–60Google Scholar
- Bowman DD (1999) Georgis‘ parasitology for veterinarians, 7th edn. WB Saunders Company, PhiladelphiaGoogle Scholar
- Gompper ME, Wright AN. Altered prevalence of raccoon roundworm, Baylisascaris procyonis, due to manipulated contact rates of hosts. J Zool (in press)Google Scholar
- Keymer AE, Read AF (1991) Behavioural ecology: the impact of parasitism. In: Toft CA, Aeschlimann A, Bolis L (eds) Parasite-host associations. Oxford University Press, Oxford, pp 37–61Google Scholar
- Moore J (2001) Parasites and the behavior of animals. Oxford series in ecology and evolution. Oxford University Press, OxfordGoogle Scholar
- Mooring MS, Hart BL (1992) Animal grouping for protection from parasites: selfish herd and encounter-dilution effects. Behaviour 123:173–193Google Scholar
- Smith EP (2002) BACI design. In: El-Shaarawi AH, Piegorsch WW (eds) Encyclopedia of environmetrics. Wiley, Chichester, pp 141–148Google Scholar
- Wright AN (2002) Changes in raccoon (Procyon lotor) parasite communities in response to an experimental manipulation of resource availability. Thesis, Columbia University, New YorkGoogle Scholar