A Comparison of ectoparasite infestation by chigger mite larvae (Acarina: Trombiculidae) on resident and migratory birds in Chiapas, Mexico illustrating a rapid visual assessment protocol
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This study presents a protocol developed to rapidly assess ectoparasite prevalence and intensity. Using this protocol during a mist-netting project in two different coffee agroecosystems in Chiapas, Mexico, data were collected on ectoparasitic chigger mite larvae (Acarina: Trombiculidae) found on resident and migratory birds. Surprisingly high infestation rates were found for some long-distance migrants, as high as 73 percent for Swainson’s Thrush (Catharus ustulatus), while many species remained uninfested. During the study, 17 of 26 species of long distance migrants and 24 of 44 resident species had at least one infested individual. Total prevalence averaged 0.18, with 0.16 for migrants and 0.23 for residents. The mite score protocol provided a useful relative measure of infestation intensity. Mean infestation intensities and abundances are reported for 70 species captured and opportunistically inspected during the course of this study. While this study does not directly link survival with infestation by ectoparasites, variation in infestation intensity among individuals could help explain differences in condition when birds arrive on the breeding range. Further study is merited on the ecology of ectoparasites, including the geographic distribution and degree to which human landscape management contributes to infestation. Constant effort mist-net monitoring stations could provide important data toward this effort by routinely collecting ectoparasite information.