Previous Dyerlab member, Anna Tucker, just got her thesis work accepted for publication in Auk. Be on the lookout for the following:
Opportunistic conspecific brood parasitism in a box-nesting population of Prothonotary Warblers (Protonotaria citrea)
Conspecific brood parasitism, while prevalent in some avian taxa, is easily overlooked in when it occurs low frequencies and therefore the ecology of this behavior has been only occasionally described in passerines. Here we describe the occurrence of conspecific brood parasitism (CBP) in a population of Prothonotary Warblers (Protonotaria citrea) breeding in nest boxes, demonstrate associated fitness costs, and investigate parasite strategy. We genotyped individuals at six microsatellite loci and used CERVUS to determine log-likelihood of maternity (LOD scores) for offspring and social mothers. We set critical cut-off LOD scores at 95% confidence for exclusion of the social mother and assignment of a parasite mother from the breeding population. Of 805 nestlings (233 family groups from 2009 to 2013), we found that 12.7% had incompatible genotypes with their social mother. Females with unrelated nestlings (hosts) fledged fewer biological offspring within the host year than non-host females despite fledging more total offspring, but being a host was not significantly associated with total reproductive success over five years of breeding. We were able to identify only ~30% of parasite females, suggesting that the majority of parasites may be floaters (i.e. non-nesters) in the population or nesting in nearby natural cavities. We found no evidence of host selection based on host age, arrival at the breeding site, or nest box productivity in the previous year. This opportunistic behavior is likely facilitated by the nesting ecology of this population, in that nest sites are limited, conspicuous, and relatively dense. Future studies investigating CBP in populations using natural cavities can help elucidate the drivers of this behavior.