Egg of <a href="https://en.wikipedia.org/wiki/Cuculus_canorus" class="extiw" title="w:Cuculus canorus">common cuckoo ssp. Canorus</a> in a clutch of <a href="https://fr.wikipedia.org/wiki/Acrocephalus_arundinaceus" class="extiw" title="fr:Acrocephalus arundinaceus">great reed warbler</a> ; collection of Jacques Perrin de Brichambaut.
<div class="fn value">
<a href="//commons.wikimedia.org/wiki/User:Erc%C3%A9" title="User:Ercé">Roger Culos</a></div>
<span class="int-own-work" lang="en">Own work</span>