Hoopoes' eggs show their true colors

[PhysOrg]

Hoopoe females use cosmetics on their eggs - and the eggs gradually change color when they are incubated, from bluish-grey to a more saturated greenish-brown. This happens because secretion from the uropygial or preen gland – a substance birds use to preen and protect their feathers – is transfered from the female hoopoe's gland to her eggs directly with the bill and by means of belly feathers. This is one of the findings from a study led by Juan J. Soler of the Estación Experimental de Zonas Áridas, CSIC in Spain, published in Springer's journal Naturwissenschaften - The Science of Nature.

 

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