Oregon

Great Gray Owls are one of the most mysterious and sought-after bird residents of California, Oregon, and Washington. While their range extends across the boreal forest of the Northern Hemisphere, the southernmost populations in the world are in the Pacific Northwest, extending into the Sierra Nevada down to Fresno County. Despite high breeding concentrations in the Wallowa Mountains of Oregon, Great Grays are of conservation concern to wildlife managers in Oregon due to declines in the overall population and loss of habitat. They are also listed as a State Monitored species in Washington, and State Endangered in California.

Even though it is the tallest owl in North America, and notoriously approachable by humans, the Great Gray is hard to find. Biologists surveying for other species may happen accidentally on the owl, but finding it intentionally isn’t easy due to its nocturnal habits, excellent camouflage, and silent flight. Additionally, Great Gray Owl won’t necessarily react to the sound of recorded calls even close to its nest site, as they are exceptionally non-territorial toward other Great Grays. Biologists would like to learn more about this hard-to-spot species and your observations entered on eBird Northwest can help. Though it’s been a century since the first Great Gray nest was found in Yosemite, Oregon’s first nest was not found until the 1950s and the first nest in Washington State was found in 1991 in the Okanogan National Forest. Sightings of nests or fledglings are especially valuable; keep an eye out for young birds, who may stay with the adult male owl until October. If you use BirdLog for field entry, we encourage eBirders to log into the eBird portal online after a Great Gray sighting and add appropriate eBird Breeding and Behavior Codes to any reports.

Where to Look: Great Gray Owls use a variety of habitats in our region; they are not restricted to the high mountain meadows that are commonly believed to be their favored habitat. In the southern Sierras, they can be found in the 4000-6000’ zone. In the Sierra foothills of central California, the species nests in oaks along riparian strips at around 2000’. In western Oregon they are found in the wet meadows of the Cascades, but also in low elevation oak-madrone forest in two areas of the Siskiyous. In the Blue and Wallowa Mountains of Oregon and Washington, they nest in coniferous forests. The northern Washington population is found in the coniferous-rimmed meadows of the Okanogan Highlands.

Nest Site Types: Breeding populations survive in isolated pockets where large trees with consistent canopy cover, their preferred nesting habitat, is still available. Great Gray Owls do not build their own nests; they may use old Red-tailed Hawk, Common Raven, Northern Goshawk, or squirrel nests. In some areas they use mistletoe brooms as a nest platform. They also will nest within rotted-out snags that are at least two feet in diameter and at least twenty feet tall. Great Grays will sometimes adopt manmade nest platforms, and there are many examples of successful programs that provide nest platforms in areas with good habitat but few nest options. The Whitman-Wallowa National Forest has had an active platform program in place for the past quarter-century. In Jackson County, Oregon, Rogue Valley Audubon has now initiating a citizen science nest platform project. At Klamath Marsh National Wildlife Refuge, Great Grays regularly use platforms built in lodgepole pines within the refuge.

Great Gray Owl Foraging: In addition to good nest sites, the Great Gray needs small open meadows with dense populations of small mammals for hunting. Their prey include voles, moles, shrews, pocket gophers, and other small creatures that live in meadow grasses. Relative to their large apparent size, which is mostly feathers, their body mass is quite small, and so they rarely catch any prey that weighs any more than two ounces. This means that where their ranges overlap, Great Grays do not compete with Great Horned or Snowy Owls, which are heavier species that consume larger prey. However, the bulkier Great Horned Owl is known to prey on Great Grays. Therefore, when birding in areas where Great Horned Owls are active, it is important to not put Great-Gray Owls at risk by soliciting responses or accidentally flushing roosting birds.

Birders can use eBird to help them find Great Gray Owls in their region. eBird Range and Point Maps and Rare Bird Alerts are great tools for learning about the latest nearby sightings, while Bar Charts, Targets, and The Hotspot Explorer can help birders find locations where Great Grays are consistently found.

Article by Harry Fuller