Avian Conservation and Ecology (Dec 2020)
Nest box location determines the exposure of the host to ectoparasites
Abstract
Nest box supplementation is a widely used technique to aid in the conservation of cavity nesting bird species. However, the criteria to choose the best location for nest boxes has seldom considered the likely exposure of cavity-users to parasites. Birds host an impressive diversity of ectoparasites that may have detrimental effects on their fitness. Here we focus on the ectoparasite infracommunity of a secondary cavity nesting bird species, the European Roller (Coracias garrulus), breeding in nest boxes in a semiarid environment. During three breeding seasons, we examined the composition and abundance of parasites at the nest level and explored their spatial structure and the effect of nest-site type, breeding phenology, and host number (brood mass) on the variability of the infracommunity. Nest location (nest boxes on trees vs nests on cliffs and human constructions) contributed the most to explain differences in prevalence and abundance of the various ectoparasite species during the three years. Host breeding phenology consistently affected the abundance of the most prevalent and abundant ectoparasite (Carnus hemapterus) and also the abundance of biting midges and blackflies, but only during some years. Host brood mass had no significant influence on any ectoparasite. Neither the occurrence nor the abundance of the infracommunity of parasites had a significant spatial structure. This study, performed at the host population scale, reveals that the socioenvironmental characteristics resulting from the selection of nest-site microhabitat explain most of the variation of the ectoparasite infracommunity. Accordingly, nest boxes for vulnerable species should be placed with solid knowledge of the effect of such features.
