How does a cuckoo manage to throw eggs into other people's nests
The fact that the cuckoo is a nest parasite, we were told at school. We know that the negligent mother cuckoo does not want to hatch and feed the chicks herself and throws eggs into the nests of birds of other species. But how this happens in detail is not stated in the textbooks. It's time to find out how this cunning bird operates and why its trick does not always succeed.
Among the nest parasites, which, by the way, are enough among birds, the cuckoo is a real record holder. She manages to throw eggs into the nests of 300 species of birds! At the same time, liars are very picky and they have a fairly narrow specialization. Some lay eggs speckled like wagtails, others are blue like redstails. Even a specialist cannot always distinguish an original from a fake!
To begin its "dirty work", the cuckoo patiently waits until the owners of the nest begin to lay eggs. She just hangs around near the selected nest and watches. As soon as the eggs are laid, and the parents are gaping, the cuckoo flies rapidly to someone else's home and lays its egg in it. After that, she takes one of the original eggs with her and eats it. The whole process takes no more than 10-15 seconds!
Cuckoos have a very short incubation period. Therefore, the alien chick, as a rule, hatches first. Then he is guided by instinct. The not yet fledgling cuckoo puts the eggs of the nest owners on its back one by one and simply throws them down. If there are already hatched chicks, he gets rid of them too. Thus, the cuckoo remains a non-native, but the only child in the family.
Now the foundling gets all the attention and food that the unfortunate birds bring. It grows by leaps and bounds, and screams like a full-fledged brood of chicks. Very often, the "baby" outgrows foster parents, but they diligently continue to feed the accelerator until he gets stronger and flies away.
But the trick with substitution is not always possible. Some birds recognize someone else's egg and immediately get rid of it. While science does not know exactly by what signs birds detect forgery. It may be an inaccurate color, too large a size, or the egg appeared too early. It also happens that the cuckoo is noticed in the nest.
Ornithologists observed reed warblers, which turned out to be the most vigilant of all birds. These small birds more often than others throw the cuckoo's egg out of the nest. They also bravely attack a thief if they find her near their nests.
The cuckoo is a large and strong bird, but often gets a beating from superior enemy forces. Therefore, she prefers to avoid confrontation with offended parents. To do this, evolution gave this bird a plumage like two drops of water similar to the outfit of a sparrowhawk. The disguise often works and the cuckoo manages to retreat.
Scientists conducted experiments and laid cuckoo eggs to birds that normally do not face such a scourge. These are species that do not live in nests, but in burrows, and also do not feed on invertebrates necessary for cuckoos. Nature did not prepare them for a meeting with a deceitful cuckoo, and they do not react in any way to the appearance of someone else's egg.
In general, the detective story of the cuckoo and its foundlings has not been fully studied by scientists. How does a bird manage to "fake" someone else's egg, down to the shape and color? Why do some birds easily recognize a fake, and others almost never? There are still enough questions in this case.