This week we learned that some birds aren’t so nice. In fact, they punish other birds so viciously that scientists are comparing their behavior to that of the mafia.

A few bird species, like the European great spotted cuckoo, lay their eggs in other birds’ nests so that they don’t have to spend the time and energy raising the hatchlings themselves. These birds act like a parasite, forcing the host bird to raise eggs that are not its own. But scientist were puzzled why the host bird did not simply throw the parasitic eggs out of the nest, and refuse to raise them. The answer it seems is the “mafia hypothesis.” This hypothesis suggests that host birds raise parasitic eggs because they are afraid of retaliation from the bird who laid them. Birds like the cuckoo will attack and destroy the nests of other birds who refuse to raise their young, killing all of the host’s hatchlings in the process. Because of this, it makes more sense for the host bird to expend the energy needed to raise the cuckoo’s young, rather than risk the safety of its own eggs.

The host bird’s reaction to parasite eggs in its nest depends a lot on the environment. If the bird’s nest has never been destroyed before, it is more likely to reject the unwanted eggs. Similarly, if there are fewer of the parasitic birds in the population, it is more likely to reject the eggs because there is less of a chance for retaliation. I still can’t help but feel bad for the host birds whose nests have been destroyed. Those cuckoos are a bunch of bullies!

Want to learn more? Visit https://www.sciencedaily.com/releases/2016/05/160518094714.htm