Meeting Abstract

56.5  Tuesday, Jan. 5  Investigating the costs of reproductive anemia associated with egg-production in European Starlings FRONSTIN, Raime B*; WILLIAMS, Tony D; Simon Fraser University, Burnaby rbf1@sfu.ca

Costs of reproduction are widely considered to be a driving force in shaping the evolution of life history traits. Although costs of increased egg production have been well documented experimentally in birds (e.g. decreased survival, chick-rearing ability) the physiological mechanisms underlying such costs are largely unknown – indeed this is true more generally for all costs of reproduction. Egg production in birds is associated with reproductive anemia, defined as a reduction in hematocrit, hemoglobin, and red blood cell number, which can persist beyond clutch completion. It has been suggested that reproductive anemia might provide a “non-resource based” mechanism underlying costs of egg production. For example, if anemia persists through offspring rearing this might reduce a females’ aerobic capacity and flight performance providing an explanation for reduced provisioning ability and decreased reproductive success. We are testing this hypothesis in a free-living population of European starlings (Sturnus vulgaris) by experimentally manipulating hematocrit in egg-laying females using the drug phenylhydrazine (PHZ). We characterized the hematological status of both control and experimental females through repeat measurement of hematocrit and hemoglobin concentration at various stages of breeding. We then assessed potential costs of increased anemia through measurement of timing of reproduction, clutch size, egg size, incubation duration, offspring quality and offspring sex-ratio, maternal and paternal provisioning efforts, and fledging success.