May 31, 2008

Pygmy Owl May Be Endangered Species

The formerly endangered cactus ferruginous pygmy owl -- the little bird that stopped bulldozers and shaped growth on the Northwest Side for several years -- is being considered again for endangered listing.

The U.S. Fish and Wildlife Service listed the 7-inch, 2.5-ounce, lizard-eating owl as endangered in 1997 but removed the bird from the list in 2006, citing a healthy population in Mexico.

The federal wildlife agency responded Friday to a petition by the Center for Biological Diversity and Defenders of Wild-life, saying genetic, taxonomic and habitat information "may warrant federal protection as a threatened or endangered species under the Endangered Species Act."

The federal agency agreed to reconsider listing the bird as endangered based on what a spokesman said was new information that was not available or could not be considered when the bird was delisted in 2006.

"What it allows us to do is take a fresh look at the pygmy owl with a potential of listing it," said Jeff Humphrey, a Phoenix-based spokesman for the Fish and Wildlife Service.

"At this point, we're not making that determination. We're saying the petition does have substantial information that will lead us to do a broader analysis."

But the Center for Biological Diversity's Noah Greenwald said the federal agency's statement was "misleading," and that the information was available at the time of the listing.

"We pointed out at that point that there's a separate sub-species that they should be looking at," Greenwald said.

"There have been some changes in the Department of Interior and in Congress.

"So, they're now considering information that was technically available to them in the first place. Our position is, it should never have been delisted in the first place."

Since the delisting, conditions have deteriorated for the owl in a number of ways, said Matt Clark, a conservation biologist with Defenders of Wildlife's Tucson field conservation office.

He said even determining how many of the owls exist here is "a very difficult question, for a couple reasons."

"The Fish and Wildlife Service and Arizona Game and Fish (Department) have not had sufficient funds to conduct surveys in Arizona for the last two years," Clark said.

One of the few things they know, he said, is that some breeding pairs that were known to be in the Altar Valley southwest of Tucson aren't there now.

"There just isn't enough information. A lot of them, though we don't know for sure, are on the Tohono O'odham Reservation, and they have never done extensive surveys there. So that's a mystery."

He said the continued drought, expanded development on the Northwest Side and the invasive species buffelgrass -- which burns fast and hot, destroying saguaros -- have probably been tough on the owls. The drought affects their prey, primarily lizards, Clark said.

And development and buffelgrass are likely affecting availability of nesting cavities.

He said that although efforts are being made to control and remove buffelgrass in Arizona, the larger Mexican Sonoran population of owls is even more threatened by it because buffelgrass is encouraged there as forage for cattle.

"Other threats (to the owls) include climate change, if we're going to have prolonged droughts. The Sonoran Desert eco type will be shifting," Clark said. "Other threats include border-security infrastructure.

"One of the dispersal corridors from North Mexico into the U.S. is right there in the Altar Valley. This year, they finished constructing a seven-mile, 15-foot tall fence through that valley."

He said the owl is not a high-flying bird and may be stopped by the border fence.

The public and other government agencies have 90 days to submit testimony on the proposed relisting of the owl, Humphrey said.

And the federal wildlife agency will have one year to make a decision on whether or not to relist the owl as either endangered or threatened.

Specific genetic differences aren't spelled out in the research being used by advocates for relisting the owl as endangered or threatened.

But Greenwald said it's likely that the Sonoran Desert subspecies has traits advantageous for surviving higher temperatures and drought.

"The Sonoran Desert is a much drier habitat than they occur in in Mexico, where it is more forested and wet," said Greenwald.

"That's part of why preserving a species across their habitat . . . allows them to survive as changes occur."


The local cactus ferruginous pygmy owl: Prefers cavities in saguaro cactus for nesting.

Range of ferruginous pygmy owl: Tip of south Texas into eastern Mexico, and from Sonoran Desert around Tucson south into western Mexico.

Prey: Lizards, rodents and birds.

Length: Under 7 inches.

Weight: 2.5 ounces.

"Ferruginous" means "reddish;" refers to the owl's rust-colored feathers, which set it apart from the Northern pygmy owl.