Birds’ Signature Defense Thwarts Cuckoo Egg Forgeries

A fork-tailed drongo nest that has been parasitized by an African cuckoo (cuckoo egg on the bottom right).  PHOTO  BY JESS LUND/SWNS 

Sneaky cuckoos are being foiled in their plot to get another bird to raise their brood by its ability to identify and reject their almost identical eggs.

African cuckoos lay their eggs in drongos’ nests to avoid rearing the chicks themselves.