Nocturnal Researchers from NMSU Shed Light on Burrowing Owl's Life

Date:  Oct. 1, 1997
Editor: D'Lyn Ford  (505) 646-6528, dlford@nmsu.edu

LAS CRUCES -- Not all wildlife research consists of hiking the woods or plumbing the waters of New Mexico for rare species.

In fact, New Mexico State University researchers need look no farther than campus for a common but mysterious creature: the burrowing owl.

One of few raptors that thrives around humans, 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 munch on insects attracted to the high-powered lights, as well as feed on doves, grackles and bats.

Some of the owls allow humans to come within a few feet. Traffic and construction 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 most male owls stay for the winter, while females leave? Where do they go? Why do females return to the same general area, though not always the same mate?

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, NMSU adjunct wildlife professor, and Carol Finley and Susan McClenahan, master's students in wildlife, those questions translate into hours of painstaking work, observing, banding, weighing, measuring and protecting burrowing owls.

Though most of the owls are known by burrow number -- "number 8 near Breland Hall" -- a few have nicknames, like the "bleacher bird" that hangs out in the upper seats at the baseball field and the "zucchini bird" that apparently carried a squash home.

No corner of the owl's life, especially its mating habits and sex life, escapes researchers' curiosity. One area of particular interest is why in most years all female owls leave for the winter. When females spend the winter, as they did last year, they occupy a burrow with a mate.

"We think that staying may give the females an edge on starting nesting with that mate the following year," Arrowood said. Females that spend winters away always seem to return to the same area, but not always to the same mate. They often start breeding later.

As part of her master's work, Finley has spent hours eavesdropping on owl courtship, recording and comparing the males' mating calls. She wants to find out whether a particular style is more effective in attracting females.

Finley's keen ear can now tell the owls apart. While some males seem to prefer a low-key style, others add flourishes to their calls that set them apart.

McClenahan wants to know what happens after owls pair up -- and whether they stray or stay faithful to their mates each season. Because males and females hunt separately, it's possible that owls seek out companionship with neighbors, especially in areas with many adjacent burrows.

To find out, researchers plan owl "paternity tests." To determine parentage, they will compare blood samples from chicks with those of the adults in the home burrow and those of neighbors.

Because owls are nocturnal hunters, the research is truly a pursuit for night owls. Arrowood, Finley and McClenahan spend many late nights watching and waiting in weather that ranges from single-digit temperatures to summer storms.

Though placid creatures, the owls aren't always cooperative. "We've had a particularly difficult time getting samples from the males for the blood tests," Arrowood said.

For now, those elusive owls, like the researchers' questions will have to wait another night.

• NMSU's Fishery and Wildlife Science Department