"There are various species of Brood Parasite birds. This means that these birds will lay their eggs in another birds nest so that victim bird has to raise the young. When the baby parasite bird hatches, it will often try killing the other young.

Victim birds have various defense, but the coolest ones to me are some of them basically printing barcodes on the eggs so they know if one doesn’t belong, and some of them singing a specific song to the egg, and if the hatched chick can’t replicate the song, it gets yeeted from the nest"