Have you ever been at a family reunion? What did it feel like to look around and recognize lots of familiar faces? There were probably plenty of relatives in the room you'd never seen before, too. Did you still recognize them?

Other animals learn to recognize their relatives by familiarity too. They learn the traits of their siblings or offspring when they interact with them, and treat strangers as non-relatives. But that could lead to mistakes. 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.

Tthat's usually what happens. But there are some animals that can tell who their relativs are, even when they aren't familiar.

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 chaise 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, even for humans.

Read more

• Our closest relatives can plan ahead, too
• How plants communicate with their family trees
• The family tree of arctic sled dogs

Source

• IFL Science - Siberian jays know who their family are, even if they're only distantly related