Before they have hatched from their eggs, baby birds appear to be able to communicate with each other to warn of the presence of danger by vibrating. This warning allows the chick to remain within the relative safety of their shells until the danger passes.
Researchers from the University of Vigo studied yellow-legged gulls and discovered one of the most sophisticated examples of embryonic communication. The team collected 90 eggs from a breeding site in northern Spain and divided them into groups of three.
Six days before the eggs were due to hatch, the researchers temporarily removed two of the three eggs in each nest, and exposed them to either white noise, or a predator alarm call. This was done four times a day, every day, until the eggs hatched. Each time the same two eggs from each nest were exposed to the noises, while the third remained in the nest. After being returned to the nest the eggs that had been exposed to the alarm calls vibrated, seemingly sharing information with their siblings about nearby dangers.
Compared to the eggs exposed to white noise, the eggs that had been exposed to the alarm calls underwent genetic changes that meant they hatched more slowly. They also showed higher levels of stress hormones, had shorter legs, were less vocal and defensively crouched more often.
These changes were seen in the hatchlings from the eggs that had been exposed to the alarm calls, and the egg that had remained in the nest. By sharing information with their siblings, the exposed eggs were able to share a fitness advantage with their siblings that allowed them all to be better prepared for life outside the shell.
Source: Cosmos Magazine
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