Cuckoo Egg (image) Max-Planck-Gesellschaft Caption The cowbird is not picky when it comes to selecting its hosts: it can choose from among 140 species with quite different eggs. Although the hosts can easily recognize the foreign egg, they frequently hatch it. The cowbird uses a trick to ensure that it doesn't have to adapt its eggs to resemble those of other species. By employing retaliation measures, it forces the step-parents to accept the egg. Credit GalawebDesign/This file is licensed under the Creative Commons Attribution 3.0 Unported license: http://en.wikipedia.org/wiki/File:Eastern_Phoebe-nest-Brown-headed-Cowbird-egg.jpg Usage Restrictions None 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.