Study reveals birds form close bonds just like humans

By Stephen Beech

Birds form close bonds, just like human friendships, reveals new research.

Starlings show “reciprocity” - helping each other with the expectation that the favor will eventually be returned, say American scientists.

Humans who are not related by blood help each other repeatedly over time.

But the idea that such interactions occur in the animal kingdom has been difficult to prove, until now.

The new study of African starlings draws on data gathered over 20 years.

The research was led by Alexis Earl, a former PhD student in the lab of Professor Dustin Rubenstein, of Columbia University in New York.

Dr. Rubenstein said: “Starling societies are not just simple families, they’re much more complex, containing a mixture of related and unrelated individuals that live together, much in the way that humans do.”

The fact that animals help their direct blood relatives, or kin, with the goal of boosting their genetic fitness and prolonging their genes, has long been known in the scientific community.

Dr. Rubenstein says starlings do preferentially help their relatives, but many birds also help non-relatives.

Dr. Earl and her colleagues discovered that the non-relative helping occurs through the formation of these reciprocal helping relationships, which sometimes take place over many years.

But proving that type of reciprocal behavior extends to animals other than direct relatives is difficult as it requires large amounts of data gathered over long stretches of time.

The new study, published in the journal Nature, draws on 20 years of research that Prof Rubenstein and his colleagues have conducted on African starlings living in the east African savannahs.

From 2002 to 2021, the researchers studied thousands of interactions between hundreds of birds, and collected DNA from individuals in the population to examine genetic relationships.

By combining 40 breeding seasons’ worth of behavioral and genetic data, the team could analyze if the birds preferentially help relatives or if they helped non-relatives, even when relatives were available, or specific individuals over time.

The researchers found that helpers preferentially aided relatives, but also frequently and consistently helped specific non-relative birds, even when relatives were available to help.

Dr. Rubenstein, said: “Many of these birds are essentially forming friendships over time.

“Our next step is to explore how these relationships form, how long they last, why some relationships stay robust, while others fall apart.”

The data builds on decades of research collected by Dr. Rubenstein and his colleagues and students on how and why animals socialize.

They have examined animal societies not just in birds, but also in a range of species around the world, including snapping shrimp throughout the Caribbean, wasps in Africa, beetles in Asia, and mice and lizards in Australia.

Dr. Rubenstein added: “I think this kind of reciprocal helping behavior is likely going on in a lot of animal societies, and people just haven’t studied them long enough to be able to detect it."