TUCSON, Ariz. - Some human residents of the desert on the edge of this city grind their teeth when they hear the single-note call of a cactus ferruginous pygmy owl. The tiny owl, which lives in saguaro cacti and ironwood trees surrounding their houses, sounds a monotonous whistle that irritates people so they feel like "blasting the thing," says a recent Game and Fish Department report.


Lately, though, it is developers who find themselves most frustrated by the owl.


In late February, the U.S. Fish and Wildlife Service formally listed the bird as endangered. Ironically, the listing comes less than a year after state surveys located at least a dozen owls on privately owned desert northwest of Tucson, in the path of the city's growth. This was more owls than anyone knew existed in the last 20 years.


Now, these owls could do something no environmentalist or politician has been able to do: slow or scale back the new subdivisions that are ripping through the Sonoran Desert.


The owl stands less than seven inches tall, weighs less than three ounces and is reddish-brown (hence, ferruginous), with a streaked, cream-colored belly. Until the 1996 discoveries, experts thought the bird had largely vanished from Arizona. Arizona biologists aren't sure why so many suddenly turned up in the Tucson area, although the birds appear to have been drawn to the ironwood tree stands that are thicker in northwest Tucson's mountain foothills than virtually anywhere else in the United States (HCN, 10/3/94).


Now, environmentalists are almost certain to sue to block additional work on two of the Tucson area's largest developments: Red Hawk and Rancho Vistoso, both planned for 5,000 to 10,000 homes, several golf courses and three resort hotels each. The developments lie in lush desert foothills a few miles from where state biologists found the owls last year.


The biologists found the owls on privately owned tracts ranging from less than 10 to 40 acres, near low-density housing. Although a separate survey of Red Hawk's 5,500 acres found no owls there, it could be because the developer surveyed his project in the fall, not between January and June when biologists say the reclusive birds are most likely to be calling.


"These owls migrate. They have to come from somewhere, and the development can block a migration path or their dispersal even if it isn't bulldozing the saguaros that pygmy owls nest in," said Peter Galvin. Galvin is a conservation biologist for the Southwest Center for Biological Diversity, which had petitioned in 1992 to get the bird listed.


Developers have maintained from the start of the controversy that southern Arizona is at the fringe of the bird's range and that it makes little sense to list it as endangered.


David Mehl, president of Red Hawk's Cottonwood Properties, said he thinks no owls live on the Red Hawk acreage because his biologist could not find even old owl scat on the property.


The bird's listing is "dishonest," says Alan Lurie, executive director of the Southern Arizona Homebuilders' Association. "Experts tell me the bird is prolific in Mexico (so) it is not truly endangered."


The U.S. Fish and Wildlife Service, however, says that studies and surveys found the owl was common to abundant in Southwestern cottonwood-willow riparian forests and mesquite bosques until the mid-20th century. Those habitats started disappearing due to damming, groundwater pumping, grazing, mining and firewood cutting.


State game officials and former federal biologist Tim Tibbitts said that the bird still can co-exist well with humans living in low-density housing of less than one home per acre. High-density development, common in the Tucson area, threatens it most directly, they said.


The Fish and Wildlife Service, however, may try to protect the owl using Habitat Conservation Plans, which allow development to go forward while protecting sections of the bird's habitat.


"I think it could hang on if we could conserve the desert scrub, but I don't think that's real likely," said Tibbitts, who wrote the listing proposal in 1994 and is now a National Park Service biologist at Organ Pipe National Monument in Arizona. "The political pressures are pretty overwhelming."


*Tony Davis








The writer works for the Arizona Daily Star in Tucson.