Unpredictable egg scramble throws off parasitic parents

eggs with patterns

Eggs of warblers and weavers reveal that those from species whose nests have been infiltrated by cuckoo finches have extremely complicated markings compared with those from species whose nests have not been invaded.

Caves et al/Proceedings of the Royal Society B 2015 (CC BY 4.0)

Some birds shirk their parental duties by slipping their eggs into other birds’ nests. But the birds that host the shysters’ eggs have a trick of their own — scrambling the looks of their eggs so they have distinct signatures.

Warbler species whose nests are infiltrated by the cuckoo finch and weaver species whose nests are invaded by the diederik cuckoo lay eggs with colors and markings that are individualistic and hard to mimic. Researchers report the finding in the July 7 Proceedings of the Royal Society B. Eggs of warbler and weaver species whose nests don’t get infiltrated don’t have the same degree of unpredictable patterns, suggesting that defenses against parasitic parents have evolved in the host species.

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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