Host specificity and colonization by Zachvatkinia caspica, an analgoid feather mite of Caspian Terns

Abstract

The relationships between feather mites and their avian hosts have great potential as subjects for studies of evolution and ecology. However, we must first achieve a better understanding of the ecological roles of feather mites (mutualistic versus parasitic) as well as their degree of host specificity before we can search for broad generalities at work in bird/feather-mite systems. I investigated host switching and feeding ecology in Zachvatkinia caspica, an analgoid feather mite that lives among the feathers of Caspian Terns (Sterna caspia). My approach involved imping (i.e., transplanting) mite-free feathers from California Gulls (Larus californicus) and Caspian Terns onto mite-infested Caspian Tern wings and quantifying the extent to which mites colonized the newly introduced feathers. This approach allowed me to expose the mites to both host and non-host feathers as well as to the presence or absence of preen oils collected from the two bird species. Mites "incubated" on tern wings showed no obvious avoidance of gull feathers or preen oil. This colonization of gull feathers suggests that some mite species have the potential to occupy a number of host species and that host switching in nature may be limited by infrequent opportunities to colonize nontraditional hosts.