Demographic patterns of feather damage from chewing lice in Tree Swallows

Birds are commonly infested with feather chewing lice that have the potential to affect their survival and reproductive success. We examined the demographic patterns of damage to wing and tail feathers caused by chewing lice in Tree Swallows. We estimated feather damage by counting the number of louse-chewed holes in the primary and secondary feathers and tails of swallows nesting in boxes in west Michigan and compared the number of holes found in the feathers of breeding second-year (SY) females, after-hatching year (AHY) females, after-second year (ASY) females, and males. ASY-females had significantly fewer holes than did SY-females, AHY-females, and males. For all categories of breeder, there were no significant differences in the number of feather holes between swallows that returned to breed and those that did not. SY-females and males had significantly more holes in their first than in their second breeding season. For all categories of breeders that returned to breed more than three times, the number of holes was consistent from year-to-year. SY- and AHY-females and their mates did not significantly differ in the number of holes, but ASY-females had significantly fewer holes than did their mates. For breeders that returned to breed, there were no significant correlations between the number of holes and morphology. In contrast, hole number was negatively correlated with mass and right wing length in males. Collectively, these data suggest little association between damage to feathers by chewing lice and Tree Swallow fitness