Cracking the mystery of not cracking the eggshell

Greater Ani is not your regular cuckoo. Rather than dump its eggs in the nests of other species it builds its own and raises its young alongside other breeding Anis. The eggs bump into each other with quite some force as parent birds turn them during incubation. Now, researchers have shown that Anis have evolved eggs with the added protection of an uncommon mineral that keeps the eggs from cracking under pressure.

Vaterite, a form of calcium carbonate, sits on the eggshell of some birds in tiny spheres of varying size. It is less stable and abundant than calcite – another form of calcium carbonate that primarily constitutes the shell. Vaterite gives freshly laid Ani eggs their white chalky appearance. As incubation progresses, it gets scratched, exposing patches of the pigmented calcite underneath. When scientists studying nesting Greater Anis (Crotophaga major) in the Panama Canal noticed this change in the egg surface they decided to look deep into it.

Read the rest of the story here at Chemistry World.

Photo credit: Christina Riehl

The 13 most shielded eggs laid by birds

Birds prepare their eggs for the worst, whether the risk comes from predators or just the location of their nests. This Easter I wrote about some of these amazing eggs for BBC Earth. Here’s one of the birds eggs I highlighted in my piece for their sheer camouflage (besides their beauty): 

Japanese Quail (Coturnix japonica)

A female Japanese quail is selective about where she lays her eggs. She chooses a background that matches either the colour of her eggs or their pattern, whichever is more striking.

If her eggs have only a faint pattern, the female chooses a site that matches their colour. But if they have a strong pattern, she goes for a site that blends with it, and which hides the contour of the egg. This means the female must know the pattern of her own eggs.

To read about other wonderful bird eggs, click here!