Mexican ground dove nest and two eggs in mesquite tree.

Mexican ground dove nest and two eggs in mesquite tree.

A white-tailed ptarmigan standing over its nest with eggs at Mount Rainier National Park.

The nest and eggs of a white-tailed ptarmigan.

The nest and eggs of a white-tailed ptarmigan.

Dallas Lore Sharp climbing up a rock slope to see nesting murres.

Dallas Lore Sharp climbing up a rock slope to see nesting murres.

Dallas Lore Sharp climbing up a rock slope to see nesting murres.

Close view of a murre sitting on an egg. A chick is perched on a rock nearby.

Dallas Lore Sharp reaching to grab a nesting murre. A chick is visible underneath adult bird.