Invading cuckoo birds may actually help their hosts survive, due to their unique method of deterring predators.
Long thought of as the free-loaders of the bird world, cuckoo birds lay their eggs in the nests of birds of different species, leaving them to raise their young on their behalf.
But researchers in Spain have found that survival rates for crow chicks in nests shared with a cuckoo were actually higher than for cuckoo-less nests.
The cuckoo chick gives off a strong smell when threatened, that causes predators such as feral cats to stay away.
This increased the survival rate of their hosts by up to 40%.
Read more at University of Oviedo