Parent–environmental interactions shape acoustic signatures in tree swallows: a cross‐fostering experiment

Abstract

Acoustic signatures are common components of avian vocalizations and are important for the recognition of individuals and groups. Th e proximate mechanisms by which these signatures develop are poorly understood, however. Th e development of acoustic signatures in nestling birds is of particular interest, because high rates of extra-pair paternity or egg dumping can cause nestlings to be unrelated to at least one of the adults that are caring for them. In such cases, nestlings might conceal their genetic origins, by developing acoustic signatures through environmental rather than genetic mechanisms. In a cross-fostering experiment with tree swallows Tachycineta bicolor , we investigated whether brood signatures of nestlings that were about to fl edge were attributable to their genetic/maternal origins or to their rearing environment. We found that the calls of cross-fostered nestlings did not vary based on their genetic/maternal origin, but did show some variation based on their rearing environment. Control nestlings that were not swapped, however, showed stronger brood signatures than either experimental group, suggesting that acoustic signatures develop through an interaction between rearing environment and genetic/maternal eff ects.

Not for Parents Only: Begging Calls Allow Nest‐Mate Discrimination in Juvenile Zebra Finches

“…Nestling tree swallows develop an acoustic signature in their begging calls through an interaction between genetic/maternal effects and rearing environment (Reers et al. ), and this brood signature is stronger when nestlings call together than when they call alone (Leonard et al. ).…”

“…In zebra finches, it remains to be tested using crossfostering experiments whether the brood signature in fledgling begging calls is explained by genetics or if it results from a convergence in call structure. Nestling tree swallows develop an acoustic signature in their begging calls through an interaction between genetic/ maternal effects and rearing environment (Reers et al 2014), and this brood signature is stronger when nestlings call together than when they call alone (Leonard et al 2009). Several bird species show convergence in acoustic structure of vocalizations as a signal of group membership in adults (budgerigars [Hile & Striedter 2000], black-capped chickadees [Nowicki 1989], red crossbills [Groth 1993], and American goldfinch [Mundinger 1980]).…”

Parental influence on begging call structure in zebra finches (Taeniopygia guttata): evidence of early vocal plasticity

“…In response to nest parasites, the host nestlings of song sparrow ( Melospiza melodia ) change their begging call to match the parasite [ 31 ]. Apart from these examples in host–parasite systems, one study in tree swallow nestlings ( Tachycineta bicolor ) suggested that brood signature in begging calls just before fledging results from interactions between environment and genetic/maternal effects [ 32 ]. However, to our knowledge, no study has tracked individual ontogeny of begging call structure to demonstrate vocal adjustment in response to social experience.…”