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 ...

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 outer layer of the eggshell in birds is in many cases covered by pigments that are assumed to be genetically determined traits with a negligible environmental component. To test the hypothesis ...

Cuckoos are nest parasites. That means they lay eggs in the nests of other birds, which then put the effort into raising the chicks. So you'd think they'd be quiet about it. Yet female cuckoos have a ...

Skies over Salthouse have kept locals glancing up, as binoculars twitch and camera shutters click in an unusually busy week. The coastal reedbeds of north ...

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 ...

There is an azure blue egg hidden in a hanging basket of ferns on our front porch. It belongs to a female house finch that just about caromed off my forehead last week when I tipped a watering can ...