Great Tits Sometimes Break Up, Bird Researchers Find

We’re talking about the birds. 

Great tits are small, yellowish songbirds common to the woodlands of Europe. Tit pairs are known to be monogamous during breeding season, splitting up after fully raising their offspring. But new research suggests that this “tit divorce” may be the product of complex social relationships formed during and after the breeding season. 

Published July 30 in Proceedings of the Royal Society B, the paper reports that not all tit pairs separate in late summer when breeding season ends. A sizeable portion of tit couples remain together throughout the winter, hitting it off again when spring comes. Other tits start drifting apart as early as late summer and eventually part ways at different times during fall and winter. In other words, tit dating status is complicated, and for reasons that aren’t yet entirely clear.

“Our results show that bird relationships are far from static,” Adelaide Daisy Abraham, study lead author and behavioral ecologist at Oxford University in the United Kingdom, said in a statement. “Divorce appears to be a socially driven process, unfolding over time.”

For the study, Abraham and her colleagues tracked individual great tits found in the woods near Oxford. These tits had a small radio tag attached to them, alerting the team whenever the birds visited one of several feeders set up by the researchers. Over a period of three years, the researchers collected great tit social data by checking which tits were associating with each other and how often.

Surprisingly, they discovered that the combination of tit pairs wasn’t as random or confined to proximity as was previously believed. While early mating might be a product of who’s nearby, whether these tit couples stay together may depend more on “social decision-making” throughout the season, the paper surmised. The researchers also found that signs of tit divorce emerged as early as late summer, becoming more prominent over winter.

“Those divorcing birds, they, from the start, are already not associating as much [at the feeders] as the faithful birds,” Abraham told NPR. “That only increases as the winter goes on.”

The paper, however, did not offer a definitive explanation for what exactly drove the tit couples apart—although, to be fair, the birds weren’t exactly forthcoming about their personal lives. But the paper does raise some questions, like, are divorced birds who find a new partner just as successful in mating? Do they exhibit different parenting patterns? Are the birds influenced by better mating choices? And do some birds get shoved out by the competition? Fortunately, the researchers seem to be asking similar questions, concluding that future studies should explore these causal relationships.

“Following these individual birds across seasons and over many years allows us to see how relationships form and break down in nature in a way that short-term studies wouldn’t,” said Josh Firth, study senior author and behavioral ecologist at the University of Leeds in the U.K., in the same statement.

“There is actually a lot more going on in those flocks of birds out your window than you think there is,” Abraham added.

When we think of non-human intelligence, we’re often drawn more to grander subjects, like extraterrestrial life. But as the new study shows, there’s still a lot for us to learn about the creatures here on Earth that are equally important and delightful—tit fidelity being a great example.