Effects of ectoparasites on seasonal variation in quality of nestling Tree Swallows (Tachycineta bicolor)

We examined the effect of ectoparasites on seasonal variation in indices of nestling quality and survival in Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) at breeding sites in British Columbia (PG) and Saskatchewan (SDNRA). In a parasite removal experiment, we detected no seasonal trend in flea abundance and, contrary to expectation, there were fewer blow flies in nests of late breeders. Negative effects of parasites on nestlings were documented at PG, where lengths of primary feather and head–bill were affected. Parental, rather than environmental, quality had the greatest effect on reproductive success at PG, as nestling survival declined seasonally regardless of treatment and despite seasonally increasing food biomass. Nestlings in control (i.e., parasitized) nests at SDNRA had elevated feather corticosterone levels, but no other effects of parasites were detected possibly because parent birds were of higher quality or parents and offspring had greater access to food such that nestlings were capable of coping with parasite-related challenges.
Source: Canadian Journal of Zoology - Category: Zoology Tags: article Source Type: research