The Function of Feathers in Tree Swallow Nests: Insulation or Ectoparasite Barrier?

Abstract

Abstract. Altricial young face two significant energetic challenges in the nest: thermoregulation and stress caused by ectoparasites. Ectoparasites feed on blood of nestlings and serve as vectors for bacterial and viral infections. Many bird species line their nests with feathers, which insulate the nest and reduce heat loss from chicks. Feathers may also affect ectoparasite numbers by serving as a parasite barrier. We tested the possible roles of nest feathers and the effects of nest parasites on the growth and survival of Tree Swallow (Tachycineta bicolor) nestlings by comparing young in control nests with those in nests from which we removed feathers and removed feathers plus used an insecticide in an attempt to reduce ecotoparasites. On the day chicks fledged, control nests had seven times more feathers in them than both categories of nests from which we removed feathers. Nestlings in control nests were larger than those in nests from which feathers were removed, and chick growth was positively relate...