Burrowing Owl

This desert bird's unique underground habitat can make it extremely vulnerable.

By VERN HEE | May/June 2012

In recent years, the burrowing owl has undergone immense habitat reduction in Southern Nevada due to regional development. Bird enthusiasts and ornithologists have come together in southern Nye County to study this marvelous bird and provide scientists with valuable baseline information in hopes to use the info to help save the bird in the face of future development.

According to the U.S. Fish and Wildlife Service, the owl is not in any danger of disappearing from Nevada, but in other states like Florida it is of significant concern. The owl is relatively small and stands nine to 11 inches tall. Its unusually long legs give it a somewhat awkward appearance. Unlike most owls, it has no ear tufts. Its body is splashed with brown and white spots to camouflage it in the desert. It has whitish eyebrows, and a dark collar interrupts the throat.

The owl’s mating season starts in March and continues through early April. The owls can utilize their burrows until October, depending upon the location within their range. Dorothy Crowe, ornithologist for the U.S. Geological Survey, has been studying the bird since 2002. “What makes the bird so intriguing is that fact it makes its home underground,” she says. “Owls that call the Mojave Desert home are believed to mate for life. Those owls that migrate to the south from the north do not.” Crowe would like to take a lead role in an owl density study sponsored by the USGS later this year.

Burrowing owls are active during the day, but do most of their hunting from dusk until dawn near their burrows. Mated owls use burrows originally excavated and utilized by desert tortoises or rodents to lay their eggs and to hide from the midday sun. Crowe says the underground habitat makes the bird extremely vulnerable to human development projects, and that breeding birds are easily crushed or killed during the construction process.

The owls live an average of nine years in the wild, and their habitat ranges from South America to the Canadian frontier. Burrowing owls prefer flat land with few trees. They eat mostly insects, lizards, and small rodents. “These birds do so well in the desert because they eat anything that moves,” Crowe adds.

The Red Rock Audubon Society, based in Las Vegas, in conjunction with the Pahrump Volunteers, has begun study of the owl with the help of the USFWS in Pahrump. The study is focused on breeding habits and what Christiana Manville, a biologist with the USFWS, calls citizen science.

Crowe has used the mating habits of the bird to develop a way of locating the elusive bird and its often hidden underground burrow. She uses a territorial vocalization played for 30 seconds during the night every three minutes to locate burrows in the desert. Her proven techniques have helped all who study the bird, including the group in Pahrump, which will be studying 30 selected owls within the town.

Manville said similar studies of the burrowing owl were conducted in Clark County in 2008 and 2009. She oversaw those studies, too, which provided scientists with the nesting success rate of the urban owls in the valley. Around that same time, Crowe also conducted a study of the wild burrowing owls in the Mojave in Clark County.

The conclusion of the studies showed that owls in the urban environment produce less chicks—4.2 to 6.2—than those in the wild. Crowe believes the reason for this is that the density levels are higher in the urban development than the wild. Owls are closer together in the urban areas and therefore have fewer chicks. “I was surprised the nesting success rate of the urban owls was so high,” Manville says.

Crowe hopes to conduct a similar density study of the owl in the wilds of Nye County if she can get the funding. She says, “There’s not much known about the natural population, and that’s really what needs to be known to determine whether the owl is something that needs to be worried about or not.”

Richard Cantino, project manager for the West Branch of the Red Rock Audubon Society, is supervising the study in the Pahrump area for Manville and hopes to provide similar information to the scientists. Cantino fell in love with the bird last year and has personally located all 30 of the burrows with the help of Crowe and other residents of Pahrump. In addition to those burrows in the study, Cantino has collected data on at least 60 other burrows. At a recent local RRAS meeting, more than 30 volunteers attended to aid Cantino and participate in the study.

Manville hopes the study will bring more awareness of the burrowing owl and its challenges to the public so that when the construction projects arise, the public will call the USFWS to report endangered owls. “The study should provide scientists with good background information about the urban population of the burrowing owl in Pahrump,” she says.