Hauber contributed to some of the only other research on incubation calling, in which the authors found that fairy wrens train their chicks to make certain sounds when born so the parents can distinguish them from cuckoos, a parasitic bird that lays eggs in other birds’ nests before skipping out on the childcare struggle. Cuckoos don’t have the brain mechanism to learn to identify a song, so fairy wrens use incubation calling as a strategy to avoid raising the parasitic cuckoos.

Joshua Rapp Learn in Smithsonian Magazine. Birds Sing to Their Eggs, and This Song Might Help Their Babies Survive Climate Change

Embryonic learning—things birds pick up from their parents while still in the egg—may play a bigger role than imagined.