Snag Trees and Healthy Ecosystems

“Dead” trees are actually full of life

Standing dead trees, called snags, provide birds and mammals with shelter to raise young and raptors with unobstructed vantage points. Large downed trees also provide important habitat for wildlife.

Hundreds of species of birds, mammals, amphibians, reptiles and fish benefit from snags for food, nesting or shelter!

Woodcutters: check snag trees for cavities

Produced in partnership with the Washington Department of Fish & Wildlife, Yakama Nation Fisheries, U.S. Forest Service – Okanogan-Wenatchee National Forest, and Yakima Valley Audubon Society, this video is designed to help educate woodcutters on how to identify cavities in snags so that these animal homes remain on the landscape.

People cutting firewood in many national forest areas, including the USFS Naches Ranger District, are not allowed to cut snags containing cavities or other obvious signs of bird or animal habitation. This video will be shown to woodcutters when obtaining permits at the Naches Ranger District, helping them to look for cavities and leave those snags standing on the landscape.

We understand firewood gathering is often an important activity for campers and others in rural areas, but it’s important to leave big snags and any dead trees with cavities or other visible animal homes standing. And when possible, to gather smaller-diameter dead wood from the forest floor!

Snags are homes

Only 30 bird species are capable of making their own nest cavities in trees. The pileated woodpecker is a famous example. Another 80 animal species, like fishers, depend upon previously-excavated or natural tree holes for their nests. Some, like wolverines, count on deep drifts piled around natural obstructions like dead tree trunks to dig their dens in winter.

Snag trees can be beautiful. They also provide vital habitat for birds and wildlife. Photo: Kelly Smith / United by Blue

The insulation of a tree-trunk home allows wildlife to survive high summer and low winter temperature extremes. Tree cavities and loose bark are used by many animals to store their food supplies, while insects living inside the dead wood eat thousands of forest pests, which can harm living trees. Woodpeckers and creepers feast on the wood-eating insects and provide “sawdust” for ants to process. Deer and mountain caribou eat the lichen growing on the trunks.

When they eventually fall into or near water and wetlands, fish and amphibians hide under and around dead wood. This aquatic “structure” provides important shelter for juvenile salmon, steelhead, char and trout. Without woody debris in our rivers and streams, these watersheds can’t provide adequate habitat for many native fish species.

Whether created through natural processes or active forest restoration, standing or down, dead wood plays an important role on the landscape.

Learn more about the debate around snag trees in this article from Yale Environment 360!

Respecting human needs while preserving habitat

We are working with partners to increase awareness of the importance of snags, and ensure forest management policies on our public lands protect the values they offer. Three national forests in Washingtonthe Okanogan-Wenatchee, Umatilla and Colville National Forests currently allow the felling of snags on portions of their lands for firewood unless there are active cavity nests in the tree.

A snag tree preserved for wildlife habitat in the Central Cascades. Photo: Chase Gunnell

Firewood cutting and snag felling is already restricted in wilderness and some sensitive areas. A firewood gathering guide from Okanogan-Wenatchee National Forest can be found here. The Okanogan-Wenatchee and other national forests also provide special firewood-collection zones. Often, these are small trees left behind or piled up after forest thinning and stand-reduction projects.

However, from the ground it can be extremely difficult for woodcutters to determine if a snag or dead tree is being used for nesting or denning. Sensible firewood-gathering regulations are needed to protect nesting and denning sites.

Due to the policies mentioned above and a lack of enforcement capacity, researchers have documented not only the continued loss of snags on the landscape, but the removal of trees providing home to wildlife such as the black-backed woodpecker, white-headed woodpecker, Pileated woodpecker, Lewis’ woodpecker and American three-toed woodpecker.

While there is important social and economic value to firewood gathering and recreation on national forests (and often some ecological benefit from the removal of small and downed dead fuels), the removal of standing, dead wood needs sensible and scientifically-sound management guidelines to help protect nesting sites, wildlife habitat and healthy ecosystems.

Learn more about snags