Bird blow flies, Protocalliphora (Diptera: Calliphoridae), in cavity nests of birds in the boreal forest of Saskatchewan

Abstract

The frequency of infestation by larval bird blow flies, Protocalliphora, an obligate blood-sucking parasite of nestling birds, in the nests of American Kestrels (Falco sparverius) was documented in north-central Saskatchewan. We found no evidence of feeding Protocalliphora in 76 intensively monitored nests. Nesting material from 92 nests was searched for puparia after chicks had fledged, and only a single P. avium puparium was recovered. We suggest that Protocalliphora are not important parasites for nestling kestrels in the boreal forest. Although Protocalliphora were also absent in four Boreal Owl (Aegolius funereus) nests, we did recover P. shannoni from Tree Swallow (Tachycineta bicolor) and House Wren (Troglodytes aedon) nests. These latter results suggest the absence of Protocalliphora in kestrel nests is probably due to species that normally infest kestrels not occurring on our study area, as opposed to the genus as a whole being absent. This study is the first to document P. avium in American Kestrel nests, and expands the known range of P. shannoni.