Not all birds lay the same number of eggs each clutch. It could also be that your birds are overbreeding, may have health issues, etc. Would need to know more about the individual situation.
all birds lay eggs
The mommy bird lays eggs and has baby birds.
The female Common Cuckoo lays her eggs in other birds nests, like the Reed Warblers and Willow Warblers nests.
All birds lay eggs.
the white bird
Birds that fly.
ostrich.
Nightingale lays eggs in the Crow's Nest.
Cuckoos do this.
This covers all birds except for flightless birds.
Kiwi are birds. The female lays eggs in order to reproduce.
Flamingos are birds, they lay eggs in a nest that they have prepared for it.