Layers of the Forest
Identify the birds at each layer of the tree canopy
Earlier this month, Seattle Audubon, Trees for Seattle, and Forterra partnered to host a fascinating workshop for the City of Seattle’s Tree Ambassadors. Seattle Audubon’s Conservation Manager, Megan Friesen, and their Conservation Science Coordinator, Jenn Lang, taught attendees about the importance of large and robust tree canopy in our urban areas as bird habitat, and Forterra’s Stewardship Coordinator, Charlie Vogelheim, led a tree walk of the Central District, exploring the diverse canopy and bird habitat within the neighborhood. The interconnectedness of trees and birds is one lens to appreciate the many benefits trees contribute to our city and the wildlife that inhabit it.
Trees are essential to the health of our cities and towns and provide a whole range of benefits. Trees provide many benefits for human communities, including their positive effect on health, local economy, safety, child development, and stormwater infrastructure. But a healthy and expansive tree canopy is also vital to another constituency of Seattle residents and visitors—our birds. Attendees learned that each layer of the tree canopy provides habitat to specific birds.
The spotted towhees are one example of a ground-nesting bird that relies on low lying shrubs like ferns and salal.
Figure 1: Spotted towhee
Ground-foraging birds include the white-crowned sparrow, fox sparrow, and song sparrow.
Mid-height Shrubs and Trees
In the second and third layers of the tree canopy, mid-height shrubs and trees that are good for nesting birds include rhododendrons, tall Oregon-grape, vine maple, Indian-plum, red flowering currant, and salmonberry. Birds that prefer nesting in the mid-canopy shrubs include the American robin and sparrows. Golden-crowned kinglets, ruby-crowned kinglets, and white-crowned sparrows forage for the many berries and insects that can be found in the second and third layers of the canopy.
Figure 2: Song Sparrow
Upper Layer—Conifers and Hardwoods
The highest layer of the urban tree canopy consists of conifers and hardwoods. Nesters that prefer tall, mature Douglas-fir, western hemlock, and western redcedar include the American crow and varied thrush. Cavity nesters that prefer to rear their chicks high off the ground in this layer include woodpeckers, brown creepers, and red-breasted nuthatches.
Figure 3: Golden-crowned kinglet
The black-capped chickadee and golden-crowned kinglet rely on the upper layer of the tree canopy for foraging purposes.
Figure 4: White-crowned sparrow
Hardwood trees in the upper canopy important for tree canopy include big-leaf maple, red alder, madrone, Pacific dogwood, and Oregon ash. The American goldfinch, American robin, and American crow nest in these hardwoods. White-crowned sparrows, black-capped chickadees, American goldfinches, and American robins depend on the upper canopy for forage.
Figure 5: Red-breasted nuthatch
Figure 6: Varied thrush
Stumps and Snags
Even standing deceased trees are important habitat dead stumps or tall snags provide vital habitat to wildlife seeking food and shelter. In particular, woodpeckers, red-breasted nuthatches, and brown creepers all rely on snags and stumps for habitat. (While great habitat, we recommend consulting a certified arborist before letting a snag stand on your property to make sure it is not a safety hazard.)
Figure 7: American robin
Figure 8: Black-capped chickadee
Seattle—Vital Stop on the Pacific Flyway
Seattle’s resident birds require an extensive and diverse canopy. A robust canopy also provides vital habitat for migratory birds like the Western Tanager and Wilson’s Warbler that depend on this habitat for nesting and foraging during their long migration. Seattle sits within the greater Pacific Flyway, the route along the Pacific coast that takes migrating birds between south and central America, extending from Alaska to Patagonia. Accessible and healthy habitat, particularly in our urbanized areas, is imperative for local and migratory bird populations.
Next time you pass your favorite urban tree be sure to look up and see if you can spot one of the many birds that call it home!
You can learn more about the work that Seattle Audubon is doing to capture Seattle’s urban forest habitat here.
Forterra partners with the City of Seattle to coordinate their Tree Ambassador Program. Tree Ambassadors are volunteers who help care for Seattle’s trees and make a positive difference in Seattle’s urban forest. They care for urban trees in public landscapes throughout the city and they write and lead tours of the urban forest for their friends and neighbors. Tree Ambassadors help build community and create a culture of caring for our community’s forests. Tree Ambassadors are helping Seattle’s goal to reach 30% canopy cover by 2037. Learn more here.
If you are interested in becoming a Tree Ambassador and leading Tree Walks in your neighborhood, join us at our upcoming Tree Walk Training! Anyone is welcome! RSVP Here.