Date: May 2, 2019
Source: Oxford University Press USA
A new study in The Auk: Ornithological Advancessuggests that some birds prioritize social information over visual evidence when making breeding choices.
The quality of an environment can be difficult for a bird to assess and, therefore, continuously gathering information is a good way to stay up-to-date with breeding conditions. In this field study, researchers tested how the wild Zebra Finch (Taeniopygia guttata) is attracted to successful nest sites. They presented the Zebra Finch with different visual or acoustic cues in nest boxes, simulating the presence of small or large broods, in order to test how birds assess the quality of a potential breeding site.
When discussing the costs and benefits of social information, scientists often argue that socially acquired knowledge is less reliable and more prone to deception. The sounds made by nesting birds, however, are honest indicators of the number of chicks. Predators can use these cues to locate nests. While the calls of chicks serve as signals for the parents and siblings and (inadvertently) also as cues for predators, it is unknown whether chick calls can also function as cues for prospective breeders.
Researchers here aimed to test which social cues from the nests of Zebra Finches attract other Zebra Finches. In two separate experiments, they presented wild Zebra Finches with either acoustic cues (playback of chick calls) or visual cues (eggs) with either small or large broods. Using playbacks of chick calls or nests with unhatched eggs, respectively, allowed them to completely discern brood size from parental activity.