For flycatchers, the attractiveness of male birds is tied to the length of their sperm.

Numbers of avian species in the Mojave Desert have fallen.

Female zebra finches prefer red-beaked male finches over their orange-beaked counterparts.

Osprey numbers are recovering after a drop in contaminants in the Delaware Estuary.

Ornithologists tagged 27 juvenile birds to track the way they use updrafts of air heated by the sun to migrate over long distances.

Chickens immunized against Marek’s disease virus are apt to spread more-virulent versions of the pathogen, a study shows.

A 2-day meeting may decide how much and which parts of 2 controversial H5N1 flu studies will be published.