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Tri-Rivers champions Burrowing Owl habitat restoration efforts Story and photos by Bradly Trumbo While the Walla Walla District manages more than 50,000 acres for wildlife habitat, planting and maintaining native vegetation are not the only beneficial measures in the quiver. […]

Tri-Rivers champions Burrowing Owl habitat restoration efforts

Story and photos by Bradly Trumbo

While the Walla Walla District manages more than 50,000 acres for wildlife habitat, planting and maintaining native vegetation are not the only beneficial measures in the quiver. Native plant communities generally benefit wildlife species, but at times, particular habitat needs may be most appropriately met with an artificial flavor. The western burrowing owl (Athene cunicularia hypugea) is a peculiar owl species that inhabits a large portion of Washington State, including the Walla Walla area. Their range extends from Mexico to Canada, and some northern individuals migrate and overwinter in the southern latitudes. However, burrowing owl habitat and distribution has declined considerably over the past approximately thirty years; their biggest threat being habitat lost to land development. For this reason, the burrowing owl is listed as a “Species of Greatest Conservation Need” by the Washington Department of Fish and Wildlife, and a national “Bird of Conservation Concern” by the U.S. Fish and Wildlife Service.

Contrary to their cousin owl species, these adaptive creatures occupy open prairie, grasslands, and shrub-steppe landscapes with low-growing vegetation. Named for their ground nesting behavior, burrowing owls generally utilize burrows abandoned by small mammals such as prairie dogs.
Walla Walla District HMUs, being protected from the threats that burrowing owls face, are ideal lands for habitat “restoration.” Restoration efforts on Corps HMUs largely focus on installing artificial burrows, providing nesting opportunity and protection from predators.

Upon being hired in 2016, Wildlife Biologist Jim Castle came up to speed on the Tri-Rivers lands and immediately prioritized burrow sites for this curious owl.
“Burrowing owls are native to the area and are an important ecosystem engineer and keystone species.” Jim explained.

Upon forming a considerable partnership with the US Fish and Wildlife Service, The Global Owl Project, and the University of Idaho, sites were selected for artificial burrow installation. Jim further explained that Corps lands near Ice Harbor Dam provide ideal habitat sites because the terrain is “…relatively flat with a good population of burrowing rodents, an abundance of insects, and a lack of predators.”

Artificial burrows were designed as far back as the 1970s, and have since been research and adjusted to relatively standard criteria based on natural burrow selection.
To mimic natural burrow criteria, the US Fish and Wildlife Service recommends burying half of a 55-gallon drum as a nest chamber with the floor three-feet below the ground surface. Ten feet of 6-inch diameter, corrugated drain pipe with a 60-degree arc and 15 to 25-degree slope up to the ground surface serves as the entrance tunnel.

The entrances must be clear of vegetation and provide good visibility to the surrounding area. Nearby perches such as snags (dead trees or brush) may also be desirable. Tri-Rivers installed 14 artificial burrows during the early summer of 2017, but the Mill Creek Project was also on the band wagon receiving two artificial burrows. In November, 2017, local Eagle Scout, Sean Cozart of Troop 693, cooperated with Mill Creek staff to supply and install two artificial burrows to satisfy his Eagle Scout project requirements.

“I have always been interested in birds, and I chose this project because of the benefit it provides to for the burrowing owls, which were here historically.” Said Sean, as he and eight of his troop members shoveled soil overtop the burrows. 

U.S. Army Corps of Engineers Mill Creek staff work with Eagle Scout Troop 693 to supply and install two artificial burrows for the western burrowing owl (Athene Curicularia hypogea) on the Mill Creek Project. Burrowing Owls are listed as a Species of Concern in Washington and need a dry, open area with low vegetation. It was once broadly throughout western North America, but has declined in the last 30 years.

U.S. Army Corps of Engineers Mill Creek staff work with Eagle Scout Troop 693 to supply and install two artificial burrows for the western burrowing owl (Athene Curicularia hypogea) on the Mill Creek Project. Burrowing Owls are listed as a Species of Concern in Washington and need a dry, open area with low vegetation. It was once broadly throughout western North America, but has declined in the last 30 years.

It is unknown how quickly owls may inhabit the new burrows, but in areas with existing colonies, owls have occupied newly installed burrows within a day. Jim Castle is hoping the owls will find the new burrows during their annual migration and return to them in spring of 2018. If the habitats are not occupied naturally, efforts will be made to cooperate with the Umatilla Tribe to transplant owls from nearby sites for colony establishment. The installation and future occupation of the new burrows at both projects not only provides a unique opportunity to establish a species of concern on Corps-managed lands, but also provides significant public opportunity.

Several burrow locations at Ice Harbor are accessible by vehicle allowing for classroom participation in the field. Educational opportunities also include research on how these new habitats are colonized, as well as colony behaviors, and students and members of the general public will have the opportunity to engage in volunteer monitoring programs. Perhaps the most wide-reaching public benefit will be the wildlife viewing and photography opportunities.

Although “restoration” sounds puzzling when referring to artificial habitat development, make no mistake in understanding that these artificial burrows provide a rare opportunity for burrowing owls and Corps public land patrons. From expanding local nesting habitat, to providing new public wildlife education and viewing opportunity, the Corps can be proud of its burrowing owl habitat restoration efforts.

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