As avian embryos develop, they draw needed calcium from the inner most layer of their eggshell, which in turn thins the eggshell and facilitates hatching. Yet, parasitic cuckoos, which lay their eggs ...

The Cuckoo (Cuculus canorus) is an interspecific brood parasite that mimics the eggs of its hosts. In this study we tested the resemblance between Cuckoo and host eggs in four host species breeding in ...

Using multiple logistic regression analysis, we investigated the influence of nest site characteristics, laying date and nest size in marsh warblers Acrocephalus palustris on the risk of parasitism by ...

Reed warblers live with the threat that a cuckoo bird will infiltrate their nest, remove one of their eggs, and replace it with the cuckoo's own. This 'parasitism' enables the cuckoo to have its young ...

THE exhausting chore of raising young is one a few birds manage to avoid. By laying their eggs in the nests of others, they dupe those others into feeding their nestlings. Such brood parasitism has ...

This story appears in the January 2018 issue of National Geographic magazine. For the care and feeding of its offspring, the common cuckoo outsources. When she’s ready to lay an egg, a female Cuculus ...