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A Relationship Between Avian Foraging Behavior and Infestation by Trombiculid Larvae (Acari) in Chiapas, Mexico

Dietsch, Thomas V.
Biotropica 2008 v.40 no.2 pp. 196-202
Acari, agroecosystems, birds, chiggers, dry season, ectoparasites, finishing, foraging, habitats, linear models, parasitism, risk, Mexico
Birds face varying risk from parasites as they select and utilize habitat. Unfortunately, behavioral and habitat correlates of parasitism in birds are not well documented. This study combines data from a foraging behavior study with results from a banding study to test whether behavior and habitat affect an ectoparasite infestation by trombiculid mite (chigger) larvae on the bird community found in two different coffee agroecosystems in Chiapas, Mexico. Individuals from bird species with regular prevalence (i.e., infestation) foraged more frequently in lower vegetative layers and had significantly lower foraging height than those from species with little or no prevalence, suggesting that foraging near the ground increases exposure risk to chigger larvae. Using linear regression, across species, parasite prevalence decreased with increasing average foraging height. Lower infestation rates were found in coffee agroecosystems with higher management intensity (i.e., less shade and drier conditions), suggesting that management activities influence infestation rates. Consequently, drier tropical habitats may pose less risk to birds from ectoparasites, though seasonal prevalence was highest during the winter dry season. Although no direct link was found between host condition and infestation by chigger larvae on the wintering grounds, birds were sampled during the middle of the over‐wintering period, not the end when infestation could affect birds fattening for migration.