Ecological immunology of bird-ectoparasite systems.

Ecological immunology is a rapidly expanding field of research that attempts to explain variation in immune function across individuals, populations and species. Birds and ectoparasitic arthropods have frequently been used in attempts to measure the cost of immune function in relation to adult condition, nestling growth and other life history challenges. Unfortunately, most studies in ecological immunology have relied on assays of general immunocompetence that are not connected to actual parasites. A summary of potential interactions between the avian immune system and ectoparasites is provided and methods that can be used to test ecological questions in the context of naturally occurring host-parasite interactions are proposed.