Sex‐specific effects of predation risk on parental care in a sexually dichromatic Neotropical songbird

Predation risk affects a broad range of bird behaviours, especially
parental care. The adaptive behavioural changes presented by both parents,
however, may differ according to different levels of predation risk
suffered by each sex. This is especially prominent in sexually dichromatic
species, where one of the sexes is more visually conspicuous and hence
vulnerable to increased nest predation risk during nest visits. Here, we
experimentally investigated how predation risk affects the parental
behaviour of a sexually dichromatic Neotropical passerine, the blue-black
grassquit (Volatinia jacarina). We used playbacks of known predators and
non-predatorial control sympatric species near nesting pairs in the field.
Results show that grassquits modify their behaviour according to predation
risk and that this behavioural response is sexdependent. Males decrease
their nest visit times, become more discreet when moving towards the nest,
and stop performing sexual displays after leaving the nest. In contrast,
females tend to decrease latency to visit the nest and increase the
duration of brooding bouts. These different sex responses reduce nest
visual and acoustic detectability, since conspicuous males are readily
spotted on nests and cryptic females camouflage nestlings and suppress
begging calls. Although these behavioural changes might reduce predation
risk, there might be a cost of reduced food load to nestlings and
increased brood starvation risk. These changes in nesting activities
illustrate the behavioural adaptability of passerines to ensure offspring
survival in tropical high predation risk environments.