Rhododendron is relatively large, with many stripes on its abdomen, which looks like a sparrow hawk. When cuckoos want to lay eggs, they usually imitate the flying posture of sparrows and fly into the forest. Many birds are scared to fly away from their nests. Cuckoo saw which nest's egg pattern was similar to his own, so he ate one nest's eggs, soon laid an egg and flew away.
Because other birds didn't see through the cuckoo's trick, they still tried their best to hatch eggs as before. Cuckoo's eggs hatch very quickly, and it only takes 12 days for a baby cuckoo to hatch. Before the little cuckoo opened his eyes, he began to do something bad: he leaned back, squeezed the eggs from the nest on his back, then straightened up and threw them out of the nest. No matter how many eggs or young birds are in the nest, the little cuckoo will throw them out one by one. In this way, it can enjoy the food found by its adoptive parents alone.
Although cuckoo lays eggs in a selfish way, it is a beneficial bird, because it likes to eat Dendrolimus punctatus, which other birds don't eat.