Bird couple doesn't feed the cuckoo intruder baby until their youngs are full.

[Reporter]

Cuckoo babies are raised by other mother birds, not their own mothers. Then the cuckoo
babies push all other eggs or chicks off the nests so that only the cuckoo chick
will get the bugs or lizards that are brought in.

Well, this bird couple somehow know the difference among the chicks in their
nests and refuse to feed the cuckoo baby in the nest.

https://youtu.be/7VESFx8BJ8c

[Reporter]

How cuckoo chicks get rid of other bird eggs.

https://www.youtube.com/watch?v=9azH6VVNNy8