RESEARCH FOR NIGHT OWLS
by D'Lyn FordThis article appeared in the Spring 1997 issue of New Mexico Resources.
Not all wildlife research consists of hiking the woods or plumbing the waters of New Mexico for rare species.
In fact, NMSU researchers need look no further than campus for a common but mysterious creature: the burrowing owl.
While numerous at NMSU, the birds are endangered in Canada and California. The owl's range extends from Argentina to southern Canada. Living in the midst of more than 20,000 students and staff at NMSU, the small birds are peaceful neighbors and patient research subjects.
They can be spotted perching on traffic signs and light poles or sitting on the ground near campus stadiums and buildings. They feed on doves, grackles, bats, and insects attracted to the high-powered lights.
Some of the owls allow humans to come within a few feet. Traffic and development are their biggest enemies.
Aside from this basic information, though, little is known about the burrowing owl's life, leaving many unanswered questions for researchers.
Why do most female owls leave for the winter? Where do they go? Why do females return to the same general area, though not always the same mate? Do burrowing owls prey on other birds or merely scavenge dead ones? How do they catch bats, renowned for their radar?
Why do owls surround their burrows with animal dung before hatching time each year? What's the secret of busy father owls that deliver groceries to their families upwards of 50 times per hour? And what's with the bird that brought a whole zucchini back to the burrow?
For Pat Arrowood, a biology and an adjunct wildlife professor, and Carol Finley, a master's student in wildlife, those questions translate into many hours of painstaking work, observing, banding, weighing, measuring, and protecting burrowing owls.
On one of the coldest nights of the year, the pair made another foray in pursuit of unbanded birds - including what Finley describes as a "stinker" living near Aggie Memorial Stadium and some wary owls who make their homes in the banks of the old campus landfill.
Finley, who often detours to look for owls on her daily jaunts around campus, has an update as they depart. "I have to tell you," she says to Arrowood excitedly. "The female is still at number 8 near Breland Hall. That means they're both here for the winter." Though most of the owls are known by burrow number, a few have nicknames, like the "bleacher bird" who hangs out in the upper seats at the baseball field and the "zucchini bird" that apparently carried a whole squash to the burrow.
In late afternoon, before the owls emerge for a night's feeding, the researchers set out homemade traps. For the Aggie Memorial bird, they slip a PVC pipe with a one-way door into the burrow, allowing the owl to come outside but blocking his retreat into the hole. Over the top, they place a PVC frame that's been covered with plastic netting and spray-painted brown. "It's not high-tech, but it works," Arrowood says.
For the burrows in the banks, they insert a longer plastic pipe with a similar one-way feature, filling in the gaps around the hole with pieces of foam rubber.
In the dwindling light, Arrowood detours to the bleacher bird's daytime hangout. To learn more about owl diets, she will collect evidence of the owl's day in a Ziploc bag, including a grackle foot and several whitish, speckled pellets of undigested insect and animal parts the bird has regurgitated. Later, Finley will pick the pellets apart, study them under a microscope, and compare them to other owls' to learn more about diet variations.
Just after sunset, Arrowood and Finley return to check the traps, careful to minimize the time the owls are captive. At the stadium, they find a first. Outside the netting cage where a male owl is caught, sits an unfettered female owl. Arrowood approaches slowly. "Hello," she says softly. "What are you doing here?"
Strangely, the female bird makes no attempt to flee as Arrowood moves nearer and nearer, finally closing her hands around the owl. "She must be sick," Arrowood says, gently inspecting the bird. "She's so thin I can feel her keel," she tells Finley. Normally, the keel, or breastbone, is padded with muscles the owls use for flight.
In the cold, the owl stands little chance of surviving the night. Arrowood places the bird in the cab of her Jeep, inside a pillowcase with a zipper. Tonight she will call a bird rehabilitator in Albuquerque, and tomorrow she will send the sick bird on a free flight north, courtesy of the airline.
The male bird beneath the netting is wearing both a metal U.S. Fish and Wildlife Service tag on the right leg and two colored bands on the left, showing he has been captured before.
The researchers check the male bird's weight, which has fallen from 150 to 135.5 grams. For consistency's sake, Arrowood makes measurements and calls them out to Finley, who records them in a well-worn notebook. Arrowood briefly demonstrates how to make the four basic beak measurements, before releasing the owl into the night sky.
At the landfill, the traps are empty. Finley helps load them up so Arrowood can go home to tend to the sick bird. The elusive owls, like the answers to the researchers' many questions, will have to wait another night.