The best feature is the tail pattern. Blue-gray is almost entirely white on outer rectrices; black-tailed and California have mostly black outer rectrices with white tips or edges. Be aware that ...

In good light, black on wings and tail shine with iridescent green, blue, and violet ... rowing wingbeats, but the birds are easily able to quickly change direction in flight.

Use precise geolocation data and actively scan device characteristics for identification. This is done to store and access ...

But sound came from a treetop. When they turned their binoculars upwards, birdwatchers saw a black bird with long, ribbon-like tail feathers, longer than its body. It was a greater racket-tailed ...