The food was taken away by the father bird, and the cuckoo pecked at the father bird杜鹃鸟生气了，啄鸟爸爸 

They look like rock thrushes.

I think whoever is filming it might have saved the chicks n helped them.

So glad they started making English captions… haha. The happenings in birds nests is some of the most interesting stuff on RU-vid imo… tough life for them

Its because it is too big for the nest

It's too fat to fit in the nest.

No, because the biological chicks know that they are their parents. The cuckoo possesses parasitic instincts, so it instinctively knows that the birds that raise it are not its parents. Thus its aim is to intimidate and bully them into feeding it, unlike the other chicks.

Ellos si son más decentes, y no picotean a quien les da de comer

Die Küken sind anständig die tun ihre Eltern nicht weh. 😊