"Why, Why, Why" - there are several possible reasons birds eat eggs:
1. They are "floor eggs" - I.e. not laid in a nest.
2. The feed is deficient in Calcium and / or Manganese.
3. The feed is deficient in animal protein.
4. The nests are open to the floor - I.e. the birds can't "hide" when laying.
A. There is not enough litter in the nests or the litter is not deep enough
to provide cushion when laid.
5. There are not enough nests for the number of birds.
6. The birds are too crowded - I.e. not enough floor space, range space per bird.
7. The bird(s) are bored.
and finally sometimes a bird is just contrary!
Prof