Humans and birds have a surprising amount in common. Both can accomplish seemingly complex tasks, like distinguishing between faces and expressions and making musical instruments.

And when it comes to raising their young, deciding when to move the kids out is another thing bipeds and avians have in common.

In both human and bird scenarios, parents often encourage their offspring to leave the nest earlier rather than later. For humans, the decision is nuanced, but for birds, their lives could depend on it.

In a recent study published in Science Advances, University of Montana researchers looked at how the age when birds leave the nest affects their survival. Turns out, survival of birds is closely tied to how ready they are to fly. Younger birds are more vulnerable and less likely to survive in the wild than older ones, but older birds could crowd the nest and attract predators. 

Tom Martin, the paper’s corresponding author, is the assistant unit leader and research scientist of the Montana Cooperative Wildlife Research Unit. His past research on birds, domestic and international, sparked the current study.

As expected, younger birds had poorly developed wings and were not-so-great flyers. This makes them more vulnerable to predators, so if they left the nest before they can fully develop, their survival rate dips. The death toll for early birds can be as high as 70 percent.

Blue tit and young

But, the death toll hovers around 12 percent for late bloomers. Birds that leave the nest later were more developed and better flyers that were more likely to survive in the wild. When the researchers kept some birds, like the gray-headed junco, in the nest for a few extra days, their chances of survival increased.

Although more time in the nest could save a young chick’s life, it could spell disaster for the rest of its family. Most bird parents encourage their young to leave the nest early because more chicks mean more noise, which can attract hungry predators.

Studies in the past have looked at animals’ locomotive performance, or their ability to move, and at their survival rates. But few have looked at both these factors together in specific species, and none have examined the combination in birds.

Although the results in this study were not surprising, they’re helpful for future research.

Read the full article here


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