By Cuculus_canorus_vogelartinfo_chris_romeiks_CHR0791.jpg:, https://commons.wikimedia.org/w/index.php?curid=16077960
(*) https://en.wikipedia.org/wiki/Common_cuckoo
(*) https://ebird.org/species/comcuc
(*) https://search.macaulaylibrary.org/catalog?taxonCode=comcuc