Burrowing Owls find a home on old Army base

Burrowing Owl and chicks
A female Burrowing Owl and her chicks stand outside an artificial nest on an Army base in Oregon. The installation of burrows has helped the species recover on the base. Photo by Alexander Clark

When you hear the word predator, you rarely associate the term with cute. Nature provides exceptions, however, one of which is the Burrowing Owl. It’s hard to think of a tiny animal with an angry glare as anything but endearing. If you’ve seen its death stare, you know what I mean. The small round bird with an apparent temper is too charismatic not to love.

The Burrowing Owl is the only owl species in the world that nests underground. It is ecologically dependent on burrows. Prairie dogs, badgers, foxes, ground squirrels, tortoises, and sometimes armadillos create burrows that the owls then usurp when abandoned. (Burrowing Owls in Florida and the Caribbean are the exception; since they live in places without burrowing rodents, they dig their own burrows.) The species evolved in prairies and other environments with few trees, so it developed the ability to take advantage of underground burrows that are typically prevalent in its habitat. Nesting in burrows also protects the small birds from larger predators.

While we humans are drawn to this small owl, we have also caused lots of problems for it by altering its habitat and reducing the numbers of prairie dogs and other animals that burrow. Though no one knows the owl’s total population size, the species has been declining for decades. Fortunately, for about 30 years, scientists have been providing artificial burrows throughout the owl’s range to give the birds more places to breed — and they work really well. I recently spent time at a site in north-central Oregon where artificial burrows helped boost a small population in just a few years. If we’re going to keep the bird’s population from a continuing downward slide, such conservation work will be key.

Standing watch

At first glance, the sagebrush and shortgrass prairie seemed vacant. There was not much sound, and the majority of the movement was from the wind blowing gently against the grass. But as I drove deeper into the grasslands on the Umatilla Chemical Depot, a decommissioned U.S. Army base just south of the Columbia River in rural north-central Oregon, I spotted a small dot just above the grass line: a Burrowing Owl. Surrounded by an endless sea of grass and sagebrush, the owl stuck out just enough to be visible from atop its sentry perch.

Burrowing Owls average around 10 inches long with less than a 24-inch wingspan, and they weigh only 5 ounces. While the birds may be small, their range is vast. In North America, they span from southern Canada to southern Mexico, mostly in the western United States but also in Florida and the Caribbean islands. They’re also found throughout large parts of South America.

Females are slightly heavier than males, while males have slightly longer tails and wings, so we can’t use size to distinguish the sexes. But during the breeding season, you can use plumage to tell them apart. The first one I ever saw was grayish brown. It appeared almost as if it had been bleached. The bird was a male; males tend to be lighter in color, sometimes ashy gray to even faint white during the breeding season. Females retain their dark brown and tan colors throughout the season. Seen separately, males and females are difficult to tell apart, but side by side, the difference is easier to observe.

The reason for the contrast is still up for debate, but one theory is that since males spend much more time out of the burrow (acting as lookouts and gathering prey), their feathers feel the full force of the sun’s UV rays. Therefore, they may look washed out because their pigments are broken down by the sun. The idea seems plausible, but it’s worth noting that it hasn’t been proven scientifically.

Burrowing Owl
A Burrowing Owl scans its territory. The species is found in much of the Western Hemisphere. Photo by Tom Reichner/Shutterstock

A scarred but wild place

Umatilla Chemical Depot sits on 17,000 acres covered by high-desert grassland. It is home to seemingly endless bunkers that stand side by side as far as the eye can see. They once housed chemical weapons, which have long since been incinerated. The Depot’s buildings look post-apocalyptic. Windows have been smashed, fire scars tattoo the walls, and rust resides in every crack. As I drove farther out into the grasslands, the roads became less and less treated, and eventually I was treading on dust and sinkholes.

It’s when you begin to leave the familiar structures of humanity and enter what feels like the wild that you see how important places like this are. Far from the sounds of the highway, coyotes called routinely at dusk, and kingbirds fluttered and hawked as they caught their arthropod meals. In the early morning, it was difficult not to flush a flock of Long-billed Curlew from the grass. Burrowing Owls poked their heads above the grass line to inspect the odd hominid walking around. One thing was clear once I spent time in the Depot: It was alive and well. This wasn’t always the case, though, especially as it relates to the Burrowing Owl.

In the late 1950s, a herd of 14 pronghorn antelope were introduced to the Depot. Eventually, the herd grew to number over 300. The population, which was technically captive because it lived within a large fenced area, then plummeted due to the detrimental results of inbreeding and cheatgrass invasion. At the time, coyotes were blamed, and a massive trapping program was set up in the 1970s. During the coyote-trapping process, badgers that resided on the base were also removed.

It was a simple math problem laid out in ecological terms: If you remove the badgers, you remove the holes, which forces Burrowing Owls out. The study of ecology shows us time and time again that if you remove one piece, it always affects the rest. By 2008, the base was home to only three or four pairs of owls. It is far from the only breeding site where owl numbers fell after burrowing animals were removed.

Burrowing Owl
An owl hovers in search of prey. The birds typically fly 1-2 meters above the ground but rise to 10 meters when hovering. Photo by nektonography/Shuttestock

Widespread declines

It’s difficult to estimate the current population of the Burrowing Owl. No one has surveyed the species, but data from the Breeding Bird Survey and other sources show that it’s declining. Depending on the state, annual declines range from nearly 5 percent to less than 1 percent, but the trend is fairly evident. The main causes of the decline, says Courtney Conway, a professor of fish and wildlife science at the University of Idaho and director of the U.S. Geological Survey Idaho Cooperative Fish and Wildlife Research Unit, are the “eradication of prairie dogs and other burrowing mammals” and the conversion of natural areas to farmland.

“Like all ecosystems, grasslands and prairies have endemic species of plants and animals that only occur there, so if we continue to eliminate and or degrade a particular ecosystem, we risk causing the extinction of the endemic species that depend on it,” Conway says. “Grassland systems have been altered more than other ecosystems because they often have fertile soil and are profitable for agriculture. They are also often relatively flat and at lower elevations, so they are desirable for human development and roads.”

While the bird has experienced a slow, steady decline for decades, the good news is that at places like Umatilla Depot, turnarounds have happened relatively quickly. After the steep decline bottomed out in 2008, a Depot official reached out to David Johnson of the Global Owl Project for advice about managing owls. Johnson led a program to install artificial nest burrows throughout the property; the first burrows were placed in July 2008. Within two years, the Depot had 32 pairs, and since 2013, anywhere from 54 to 65 pairs have bred on the property each year. And the birds seem to be returning annually, too.

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Few places that are home to Burrowing Owls can claim the colorful history that the Depot can. The facility housed chemical weapons from the 1960s to early 1990s, but after the Chemical Weapons Convention was finalized in 1997 calling for sarin and other such weapons to be destroyed worldwide, Umatilla’s stockpiles were transferred and incinerated. Recently, “a Land Reuse Authority was convened to dispense with the land in an appropriate manner,” Johnson explains. About 7,500 acres went to the Oregon National Guard. “Other portions of the Depot are assigned to be taken over by Umatilla County and by Morrow County, with a remaining parcel of 5,600 acres to remain a dedicated wildlife area.”

Johnson says the as-yet-unnamed wildlife area will undergo restoration activities to promote the native shrub-steppe environment. “The degree that these various land holdings become readily accessible to the public is still undetermined,” he adds.

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Alexander Clark

Alexander Clark is an avian behavioral ecologist and a wildlife photographer. He has conducted ornithological research from the grasslands of Kentucky to the rainforests of Hawaii. In past issues of BirdWatching, Clark has written about Hawaii’s three ‘elepaio species and about the Palila, an endangered Hawaiian forest bird. Find him online at www.alexanderclarkphoto.com.

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