Take A Hike Through the Boise National Forest
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Home is where the hole is.

Very cool fact: saw-whet owls nest in trees in cavities made by pileated woodpeckers. When the pileated woodpeckers leave, the saw whet owl moves in!

Saw-whet owl in cavity

Mountain bluebirds (Idaho's state bird) can't make their own holes in snags. They look for holes left by woodpeckers. Why can some birds peck a hole in a snag but others can't? (Hint: What tools do birds have to use?)

Snag a dead tree

SnagNo way a dead tree could ever be useful. Right? Wrong!

Dead trees that haven't fallen over have a special name - "snags." Snags are real important to some birds and wildlife. Let's find out why.

Osprey perching on snagBirds and animals depend on snags for shelter, nests, or perches. Holes are great places to live. Many birds and animals use holes in dead trees. Some make their own and others look for abandoned holes to use. The holes are called "cavities," just like the holes in your teeth that get filled by the dentist.

Snag with loose barkAs a snag ages it starts to fall apart. The bark loosens and falls off. The wood softens. The tree top may break off. Eventually, snags fall to the ground and finish rotting. Each stage of the snag's decay process is used by different animals:

Broken topped snag - Bats will look for snags with loose bark. They might roost under the bark at night to digest insects.

- Pileated woodpeckers look for snags that are sort of rotten. They like soft wood to peck into.

- Goshawks and great grey owls nest where the top of the tree is broken off. A really rotten (and soft) snag with the top broken off is where chickadees like to nest.

Insect larvaeBark beetles lay their eggs in soft, rotting wood. When the eggs hatch, the larvae eat the wood. Birds and animls eat the insect larvae. Woodpeckers listen for larvae in snags, then peck around to find them. Bears rip open rotting logs on the ground looking for insect larvae to eat.

Fallen snagFallen snags shelter animals. Mice, squirrels, coyotes, and foxes might make dens in, or next, to fallen trees. Deer can hide from predators behind fallen snags.

Eventually, dead trees rot away - it can take hundreds of years!