Perched a mile high on the Boise Ridge, at the toe of Idaho’s vast central mountains before they tumble to the Snake River Plain, is the Intermountain Bird Observatory’s Lucky Peak Research Station. The site is one of only a few known locations in the western U.S. where large numbers of diurnal (daytime) raptors, songbirds, and forest owls funnel during fall migration due to its unique geography and habitat mosaic. Woodland birds tend to “pile up” on Lucky Peak to feed and rest before crossing the 50+ mile expanse of the Snake River Plain on their southbound migration. This natural phenomenon presents a unique opportunity to study the migration of many different birds in one location.
From mid-July through October, research station staff and volunteers run a 24/7 fall migration project that includes banding of songbirds, diurnal raptors, and owls, as well as a Hawkwatch monitoring station. Each fall, Lucky Peak crews capture and band between 4,000–7,500 songbirds of about 60 different species, about 1,000 hawks and falcons, and as many as 900 owls. Observers at the Hawkwatch station count 5,000–9,000 raptors of 18 different species annually. These banding and migration studies provide important data on bird population numbers, age and sex ratios, reproductive success, breeding timing, migration movements, and individual bird longevity. This information is used to study the impacts of climate change, the importance of different habitat types, and changes in species populations.
One of the research station’s most unique and intriguing efforts is the owl banding program. Conducted from late August to late October, the program targets migratory forest owls as they depart their Rocky Mountain breeding range. To capture owls, banders use vertical nets of fine, virtually invisible mesh called mist-nets. The nets have soft pockets to cushion and envelope birds as they hit the net, then the mesh fibers hold and support the birds to minimize struggle. To attract owls into mist-nets, banders use an audio lure consisting of an mp3 player and remote speakers that broadcast owl calls into net arrays. Nets are opened 30 minutes after sunset and closed 30 minutes before sunrise, with banders making net runs every 45–90 minutes.
When an owl is captured, banders gently extricate the bird from the net, place it in a soft cloth bag, and bring it to the banding station for processing. Here, banders examine each owl and record data, including condition, weight, age, sex, and a host of body measurements. Owls are banded on one leg with U.S. Fish & Wildlife Service metal bands with unique 8- or 9-digit numbers. They are then taken outside and held quietly for several minutes so their eyes can readjust to darkness before being released back into the night.
Annual owl capture numbers at Lucky Peak range from 75 to 900, with higher numbers representing irruption years for certain owl species. Since 1999, the station has captured seven different owl species including Northern Saw-whet Owl, Flammulated Owl, Western Screech-Owl, Long-eared Owl, Northern Pygmy-Owl, Boreal Owl, and Great-horned Owl. A few other non-owl critters find their way into the nets as well.
Owl Species Captured at Lucky Peak Research Station
Click on owl common names in captions for links to Audubon’s Guide to North American Birds species accounts.
By far, the Northern Saw-whet Owl is the most frequently captured owl on Lucky Peak. Though one of the most common owls in forested habitats across the northern U.S. and southern Canada, they are highly nocturnal and seldom seen. At 7–8 inches in length with an 18-inch wingspan, Saw-whets are one of the smallest northern owls. They have an oversized round head lacking ear tufts and bright yellow eyes. Their most common prey item is mice, but they also take shrews, voles—even small songbirds, chipmunks, and insects. Preferred habitat is mature forest with open understory (for ease of foraging); deciduous trees (for cavity-nests); and dense conifers (for day roosting). The male’s distinctive advertising call is described as “a monotonous series of whistled notes on a constant pitch” that can be heard up to a half-mile away. Birders refer to this vocalization as the “tooting” call. The Saw-whet's name is derived from its alarm call, which resembles the whetting of a saw.
The second most frequently captured owl at Lucky Peak is the Flammulated Owl. Until about a decade ago, this diminutive, secretive owl was considered rare. But improved census techniques revealed they are actually quite common. Flammulated Owls are a tiny 6 inches in length with 15-inch wingspan. They have short ear tufts often held flat, a short tail, and dark brown eyes. Flams are unique in subsisting almost entirely on insects, namely moths and beetles. With such a seasonal diet, they are highly migratory, heading to Mexico and Central America for winter. Preferred breeding habitat is mature, open pine/fir forest in cool, dry regions of the intermountain west, but they also breed in pine/oak, pine/juniper, and aspen forests as well. Like Saw-whet Owls, Flams are secondary cavity nesters requiring large snags (>20 inches diameter) with holes excavated by large woodpeckers. Despite its small size, Flams produce a soft, low-frequency single or double “hoot” giving the impression of a much larger owl — and one difficult to locate! Having surveyed for this owl for three summers, pinpointing these little ventriloquists took some practice.
Owl data compiled by the Lucky Peak Research Station have been incorporated into graduate thesis work and journal articles through Boise State’s Raptor Research Center and Raptor Biology graduate program. This owl work at Lucky Peak continues to shed light on our collective knowledge of these secretive and charismatic nocturnal migrants, moving like an unseen river flowing overhead on their southward journey.
What owls do you see or hear in your part of the world?
Which is your favorite owl species?
The mist-nets are officially open! Please share your recent close encounters of the feathered kind!
And Happy Owl-oween everyone….