Roland Seitre / Wildlife biologist Randy Matchett and assistant setting up a circular probe to monitor the movement of Black-footed Ferrets, as part of a reintroduction program. Montana, March 2002.

Michael Durham / Striped Skunk (Mephitis mephitis) emerges from a burrow under a chicken coop on Sauvie Island, Oregon. Photographed at night with a remote camera

Mark Moffett / Wind Scorpion (Chanbria sp) digging a burrow in the sand, southern California

Flip Nicklin / Wedge-tailed Shearwater (Puffinus pacificus) incubating egg in nesting burrow, Hawaiian Leeward Islands

Norbert Wu / Mantis Shrimp (Odontodactylus scyllarus) in its burrow, ready to strike with claws, California

Jim Brandenburg / Timber Wolf (Canis lupus) possible den site in south-facing sandy slope, Minnesota

Jim Brandenburg / Timber Wolf (Canis lupus) possible den site in south-facing sandy slope, Minnesota

Mark Moffett / Northern Beach Tiger Beetle (Cicindela dorsalis dorsalis) larva in its burrow, Martha's Vineyard, Massachusetts