The loss of survival-relevant behaviors ( McPhee and Carlstead 2010 Shier 2016), including losses in vocal diversity ( Corfield et al.
These alterations in behavioral phenotype can occur developmentally in a single generation or genetically/epigenetically across generations, and have been documented across a wide variety of vertebrate species for many functional categories of behavior, including antipredator, locomotory, foraging, refuge use, and reproductive, competitive and other social behaviors (Frankham 2008 Grueber et al. However, behavioral erosion is a common byproduct when animals are held under human care, resulting in the loss of survival-relevant behaviors, and deviations from wild-type behavior in form, or the expression of behaviors in inappropriate contexts. Animals that have spent generations under human care need to retain their natural behaviors for successful return to the wild ( Rabin 2003 McPhee 2004a, b). Whether or not animals exhibit appropriate species-specific communication is particularly important in conservation breeding programs. For instance, failing to respond to an alarm call could result in predation, or failing to adequately broadcast territorial calls could cause a loss of territory, mates, or offspring. For primarily vocal species, how individuals respond to conspecific vocal cues and signals can have survival-relevant consequences. They do illustrate, however, that not all individuals respond appropriately, so animals’ responses to vocal stimuli may be an important factor to consider in determining the release suitability of individuals.Īnimals have evolved mechanisms for communication that facilitate survival and reproduction. These results are encouraging, showing that ‘alalā exhibit relevant, species-specific behaviors despite generations under human care. We also found individual consistency in the level of vocal behavior response across all call types, indicating that some individuals are more vocal than others. Males were more likely to make these aggressive calls than females, mirroring their roles in territory defense. ‘Alalā were significantly more likely to approach the speaker following alarm call playback than other call types, and were more likely to respond to territorial intrusion calls with the same aggressive territorial calls. We presented pairs of ‘alalā with alarm, territorial intrusion, and two types of control playback calls (a non-threatening territorial maintenance call and a novel heterospecific call). We conducted our studies on breeding populations derived from a small number of founding ‘alalā maintained under human care since their extinction in the wild in 2002. We tested whether endangered ‘alalā (Corvus hawaiiensis), which are extinct in nature, have retained their natural responses to vocal calls that were previously linked to survival and reproduction in the wild. Determining if animals in conservation breeding programs exhibit and respond appropriately to species-specific vocalizations is therefore important for ensuring their survival and persistence post-release. However, both the structure of and responses towards natural vocal behavior can be lost or subject to alteration under human care. Vocal communication serves an important role in driving many animals’ social interactions and ultimately their survival.
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