This story appears in the January 2018 issue of National Geographic magazine. For the care and feeding of its offspring, the common cuckoo outsources. When she’s ready to lay an egg, a female ...

2010). These and other cuckoo hosts appear to have evolved a simple rule of thumb to direct their behavior: "eject the egg unlike your own". But how does a bird know what its own eggs look like?

Generally shy and elusive, the yellow-billed cuckoo can be easily overlooked. Its calls are usually loud and often provide the best evidence to the presence of the bird. It favors eating ...

However the cuckoo catfish eggs develop quicker, hatching first, whereupon the catfish fry either eat the cichlid fry in the mouth of their mother to be, or cause her to eject her fry prematurely.