Northwest Woodlands Magazine Article Summer Edition
- Jeanna Clifford
- Jul 7
- 5 min read
Updated: 6 days ago
Article written by Jeanna Clifford and the ORI
Standing Tall: The Obscured Life of Snags and the Owls Who Rely on Them
Owls are among the most recognized and mysterious birds of the forest, yet many people are surprised to learn that most owl species do not build their own nests. Instead, they depend on existing structures—natural cavities, clumps of mistletoe, stick nests made by other species, abandoned woodpecker holes, or broken treetops—to raise their young. This reliance makes them particularly vulnerable to forestry practices and highlights the importance of preserving these critical features in our forests. Without suitable nesting sites, some species of owls may not reproduce successfully, threatening their long-term survival.
In Northwestern forests, life doesn’t end when a tree dies, it transforms. One of the most critical but often overlooked elements of healthy forest ecosystems is the snag—a standing dead or dying tree that remains rooted in place. While to some, snags may appear hazardous or unsightly, these trees are lifelines for wildlife and indicators of sustainable forestry. They play a central role in the lives of many owl species, and their protection is crucial to biodiversity and ecological resilience across the Northwest.
The Anatomy of a Snag
The term snag typically means it’s a standing dead or dying tree formed through natural processes such as wind, lightning, disease, wildfire, insect infestation, or age-related decline. When a tree top snaps off, it’s called a broken-top snag, as the top decays, it can serve as a nesting platform for larger owls like the Great Gray or Great Horned. Where a branch breaks off, a natural cavity can be created by decay processes. Other cavities are made by woodpeckers feeding on insects and drilling their own nest holes. These cavities can serve as homes for smaller species of owls such as Flammulated, Screech, Northern Pygmy, Boreal, and Northern Saw-whets as well as other small mammals such as squirrels, bats, and insects.
Great Gray Habitat
Great Gray Owls, one of the largest owls of the boreal and montane forests, are particularly reliant on broken-top snags. These majestic owls often nest on broken-topped trees, typically favoring old-growth forests with tall canopies or boggy meadows, with abundant snags. These owls may return to nesting territories year after year, although they may move nests many miles away for reasons such as food supply, nest site availability (snags eventually fall down) or perhaps loss of habitat.
In Western Montana, the average height for known Great Gray Owl nest snags is around 32 feet, with a lot of variation from 18 to 65 feet. A recent pair has been observed nesting for the last 2 years atop a 20 foot narrow aspen snag. With this particular nest, we have partnered with Explore.org to install a live nest camera, where one can see on their website an example of a Great Gray Owl nesting on a broken-top snag. These insights can help forest managers make more informed decisions about habitat conservation.
Decoding Smaller Owl Real Estate
Some of our recent research has focused on snags for cavity-nesting owls, particularly Northern Pygmy and Northern Saw-whet Owls. These studies reveal specific patterns in tree species preference, cavity dimensions, tree size and condition.
Data from over 100 nest cavities show that Northern Saw-whet Owl nests were found mostly in dead trees with bark still intact, most commonly being found in Quaking Aspen, Ponderosa Pine, and Black Cottonwood. These cavities average 3.5 x 4 inches in diameter, and each tree often hosts two or three cavities.
Northern Pygmy-Owls, on the other hand, have a greater diversity of trees that they use, more often in live Western Larch, Black Cottonwood, and Quaking Aspen. Their cavity entrances are smaller, about 2.2 inches in diameter, and are typically found in trees with fewer number of cavities.
Snags: Cornerstones of Biodiversity
Snags support far more than owls, over 75 species of birds use cavities for nesting. Snags also provide perching and nesting sites for hawks, eagles, osprey, ravens, and songbirds; denning locations for mammals; and homes for countless invertebrates. Woodpeckers excavate nesting cavities in these snags, which in-turn, become homes for secondary cavity-nesters, such as owls.
These old, standing trees become full miniature ecosystems. Removing them interrupts complex ecological relationships that often take centuries to establish. Yet many snags are still removed out of fear they may fall, become a fire hazard, spread diseases, harbor insects, or because they appear unsightly. That is why it’s important to know just exactly what types of trees and their characteristics to leave behind.
Changing the Narrative: From Eyesore to Asset
There is a growing need to shift public perception of snags. Rather than being seen as hazards or firewood, may they be recognized as vital ecological infrastructure. Sustainable forestry includes protecting snags during harvest and, when appropriate, even creating new ones by hollowing out the tops of broken top trees, or by leaving dying trees in place to allow natural processes to occur for the future.
Property owners can take several steps to promote snag conservation:
Retain snags on your property that fall within the best nesting characteristics whenever possible and consider preserving the processes that regenerate snags for the future.
Create snags by removing the tops of dead trees and hollowing the tops out, or letting them decay
Share information with others about the importance of snags for wildlife.
Advocate for forestry policies that incorporate snag retention.
Sustainable Forestry and Snag Stewardship
For family forestland owners in the Northwest, integrating snag conservation into your forest management plan is a tangible, effective step toward sustainability. Reach out to your local State Forestry Associations, which can offer technical assistance, cost-share programs, and guidelines to help.
Working with an arborist or professional forester who understands wildlife habitat can yield long-term ecological benefits. Selective thinning, patch cuts, and wildlife tree retention strategies can be implemented to balance timber production with conservation. In addition, the habitat surrounding the snag is critical e.g. a snag in a clearcut won’t support the same species, especially the Great Gray Owl, as a snag in a forest.
Conclusion
In the Northwest’s forests, snags stand as monuments to resilience. They harbor a variety of life even in death, providing shelter, food, and breeding sites for the forest’s most secretive residents. Owls like the Great Gray, Flammulated, Screech, Northern Pygmy, Boreal, and Saw-whet depend on them, and in protecting snags, we protect an entire web of forest life.
Sustainable forestry isn’t just about the trees we harvest—it’s also about the ones we choose to leave behind. Let’s leave the right ones.
ABOUT NORTHWEST WOODLANDS MAGAZINE: The magazine was first published in 1985. Approximately 3,500 copies of the 32-page magazine are printed quarterly and mailed to the members of the Idaho Forest Owners, Montana Forest Owners, Oregon Small Woodland Owners,
and Washington Farm Forestry associations.
