Barn Swallows continue to “hunt for love” even when they are already paired. They do not seek out a good provider or a faithful partner, but only want the most attractive males, according to a study conducted by a research team at Cornell University in New York.
“The bad news for the male swallows is that the game of romantic pursuit never really ends,” said Rebecca Safran, the lead researcher. “This is something that most humans do as well – considering how much time and money to spend on appearance and social standing, even though a stable relationship has long been established,” she added.
For the barn swallow, scientifically known as Hirundo rustica erythrogaster, a good appearance means having a beautiful red chest and belly. If a male’s chest is not as dark as that of other males, the female is likely to secretly seek out a “lover.” Some unfortunate males may even end up raising a brood of their rival’s offspring.
In their experiment, Safran and her colleagues paired 30 swallows for natural mating and egg-laying. They then removed the eggs to allow the birds to mate again, and tested the eggs to identify their parents. Before the females chose their second mates, Safran photographed the males and marked their necks, chests, and bellies with red paint, leaving them to behave naturally, or used a transparent mark in case other factors like scent played a role.
They then allowed the pairs of swallows to breed again and checked the DNA of the chicks. The results showed that all the female swallows maintained a visual pairing with their original mates but “strayed” with other males. The males with prominent red markings fathered more chicks compared to their first pairing. In contrast, those with unchanged coloration sired a similar number of chicks or fewer than in the previous brood.
Ornithologists believe that feather color reflects the overall health of the bird’s offspring. For females, it serves as a cue for who they choose to mate with.
T. An (according to Reuters)
