Do Fleas, and/or Old Nest Material, Influence Nest‐site preference in Hole‐nesting Passerines?

Abstract

AbstractThis study examined nest‐site choice in a migratory population of pied flycatchers (Ficedula hypoleuca) and sympatric populations of three resident tit species (Parus major, P. caeruleus and P. palustris) in central Sweden. All four species are secondary‐cavity nesters which naturally breed in pre‐formed tree cavities but readily use artificial nest boxes. We asked whether flycatchers and tits discriminate between nest boxes that: 1. Are ‘empty’; 2. Contain old nests without ectoparasites (fleas Ceratophyllus sp.); or 3. Contain old nests with ectoparasites. We found that pied flycatchers preferred nest boxes containing old nests, regardless of whether these nests held parasites. In contrast, tits did not discriminate between the three types of boxes. Tits may pay a cost for their lack of choosiness: after the breeding season, tit nests contained more fleas than flycatcher nests. Nevertheless, parasites did not affect the choice of a nest site in any of the species studied. We suggest that the migratory flycatchers are in a hurry to start breeding upon arrival and use the presence of an old nest as a shortcut cue to assess nest‐site quality. Also, they may save valuable time by copying the choice of previous breeders. Non‐migratory tits may have more time to inspect nest sites, but do not seem to use the same cues in nest‐site selection as the pied flycatcher.