A Big Mouth to Feed (IMAGE) Norwegian University of Science and Technology Caption This marsh warbler has a cuckoo chick in its nest. It was undoubtedly unable to differentiate between the cuckoo egg and the rest of the eggs in its nest. Credit Photo: Per Harald Olsen, NTNU Usage Restrictions With proper credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.