The number of eggs a bird lays — its clutch size — varies greatly among species. You might think every species should simply lay lots of eggs because that would increase the odds of more young birds ...

"It's hard not to feel like a proud parent seeing them out there thriving and making history," London Zoo bird keeper Charlotte James said Jonny Shepherd/TNC-ZSL; TNC-ZSL The once-extinct Sihek bird ...

Fork-tailed drongos have a signature color and pattern on their eggs, which helps them avoid getting duped by African cuckoos. Hans Stieglitz via Wikimedia Commons under CC BY-SA 3.0 Cuckoos have ...

Black birds with a greenish sheen and brown heads sometimes visit my yard during spring migration. These are male brown-headed cowbirds, and they often arrive in mixed flocks of red-winged blackbirds ...

CHICAGO — It’s springtime, and the birds are chirping as they begin to build their nests. Researchers say the hands-on clock is turning back, though it happens like clockwork each year. Many species ...

Egg-collecting enthusiasts in the late 1880s knew the hobby was crucial for understanding the natural world, but likely never imagined that their research would help scientists more than 100 years ...