On A Related Matter
Like humans, animals learn to recognize their relatives by familiarity. They learn the traits of their siblings or offspring when they interact with them, and treat strangers as non‑relatives.
But that method also leads to mistakes. For example, if you switched a bird‘s own chick with an unrelated chick right after hatching, before the mother became familiar with it, it would raise the unrelated chick as its own.
Some animals, though, can tell who their relatives are, even when they aren‘t familiar.
Birds of a Feather
In 2015, a team of European biologists published evidence that Siberian jays can distinguish relatives they‘ve never seen before. These birds are scavengers that gather at carcasses. They share this food with relatives and chase others away. Their territories can include immigrants that are unfamiliar and may vary in relatedness.
If the scientists put out food, they could see who the birds shared with and who they chased away. They would need to label the birds so they could recognize new immigrants and do DNA testing to figure out how closely related the immigrants were to the resident birds.
They did all that, and showed that jays can make fine distinctions among degrees of relatedness, even when dealing with an immigrant stranger. But the jay‘s remarkable abilities weren‘t consistent. The same birds were still fooled when the scientists mixed up their chicks.
Recognizing relatives is hard, for humans and for birds alike.
Read More:
"Siberian Jays Know Who Their Family Are, Even If They‘re Only Distantly Related" ( IFL Science)
"Recognizing Distant Relatives Comes Easy to Siberian Jay" ( Bird Channel)