It stands on our property as prominent as any feature of the land we have. When we made a map of our property, we made note of the big ol’ snag’s location. I check out the kitchen window at its branches early each morning to see what bird might be perched there, surveying the land. Many hawks, vultures, crows, ravens, owls, and smaller birds are spotted making use of its vantage point.
A snag is simply a tree that has died but is still standing. As the tree declines and dies, which can be due to a myriad of reasons, the branches slowly release leaves or pine needles along with many of the smaller twigs. This can take up to 3 years! What is left is the skeleton of the tree with its major branches intact. It is like seeing an old abandoned castle keep or farmhouse now devoid of life and use. Step closer though, and you will see there is a great deal going on and it is filled with life and use. So much so, they are now called, ‘wildlife trees’. Approximately 10-20% of older-growth forested areas are snags.
Enter the woodpecker. Foothills species tend to be the Downy Woodpecker, Hairy Woodpecker, and the Northern Flicker, but there are others. As a tree begins the decay process, many insects take up residence in its layers of bark, cambium, sapwood, and heartwood.
https://www.fs.usda.gov/learn/trees/anatomy-of-tree
The woodpeckers feed on the larva and pupae of the insects, drilling into these layers of the tree to get at them. The resulting holes, some far bigger than others, become cavities for birds and animals to store food, find shelter and create nests. The more the wood rots, the softer it gets, and the bigger the drilled-out holes can become homes for families as big as raccoons, squirrels, owls, pine marten, hawks, and even bears. Most of the cavities are just the right size for smaller birds such as chickadees, wrens, and the woodpeckers themselves to create homes. Woodpeckers, actually, are so conditioned to make cavities in trees, they won’t use human-placed nesting boxes. The woodpeckers are so efficient at extracting the insects from the trees, they do a great deal to keep insect populations in control. Without them, the broad insect populations would be even far more detrimental to the forest's health.
Some snags are just at the right conditions, they become pocked with many holes like a wildlife apartment complex. Over a hundred species of birds, mammals, reptiles, insects, and amphibians make use of the snag for nests and food storage. Even solitary bees and some butterfly species use the small holes. Getting down to even smaller creatures, there is a great deal of activity in the insects, fungi, and bacteria that are a part of the decomposition party right down to the roots. These players are breaking down the wood’s cellulose, converting it to carbon dioxide and water, and sending the other nutrients back to the soil. This process will continue until there is no evidence left of the tree.
The bigger the snag, the more it can handle the construction projects of the woodpeckers and the occupation of so many forms of life. Bears and raccoons will tear off sections of the bark to reveal hordes of protein-packed insects, a super-snack for them. If the top of a snag is broken off in a storm, that break can become a great nesting area for Goshawks, Red-tails, and large owls.
In time, sometimes a very long time, even the biggest of snags will finally fall to a strong wind or merely gravity. These are the logs laying on the forest floor. The decay process is still happening and the log will fill with decomposers for many years. Snags that land in water decompose at a different pace and become perches and bridges for many animals. Picture a log lined with turtles, ducklings, or the Herron resting on a log on the lake shore.
Many property owners and land managers look to quickly remove a dead tree to reduce potential fire fuels and create a better aesthetic appeal. Thankfully, this mindset is changing, and if a dead tree can be left in place safely, it will bring a good deal of benefit to the area. There is a consideration to reduce fire fuels though. As with all things, moderation. Not every dead tree needs to be kept, especially when it does not seem to be in use by the wildlife. Each tree requires individual evaluation in its life as a snag.
Dead trees with human and structure safety are a factor to consider as well. My Ponderosa Pine snag is about 28 inches in diameter with a taproot going down 30-45 feet. It is likely not in danger of coming down anytime soon. In fact, it might stand that way for 100 years or more. Additionally, it is positioned so that, should it fall, it would not damage any structures or power lines. The smaller Aspen snags are a different matter. Their roots are shallow and they are only 4-8 inches in diameter, there’s not much to hold them in place. We push many of these snags over as we feel them loosen in the soil. Others, we remove with a chainsaw. Many trees, such as Cottonwood, rot very quickly on the inside, even before it has completely died, and will drop branches or crack the whole trunk in a wind event. Those often need professional help to remove. Check a snag over for nesting cavities before making the decision to remove it. (In fact, if you are camping on US Forest Service land, and gathering firewood, it is illegal in many forest areas to remove a snag if it has nesting cavities.) If there are nesting cavities in a snag on your own property, it might be better to wait until the fall when the nests are no longer occupied if you need to take a snag down. Check for squirrels though!
I hope you notice snags now with the changes and life they will be showing you in time.
Sources:
- https://wdfw.wa.gov/species-habitats/living/snags#wildlife
- Snag (ecology). (2022, August 31). In Wikipedia. https://en.wikipedia.org/wiki/Snag_(ecology)
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