Sunday, June 05, 2005

ENV: Declining pops

Pygmy owl dies at 6, leaves few kin to mourn
By Tony Davis, ARIZONA DAILY STAR, Published: 06.02.2005


One of the last three pygmy owls known to live on Tucson's Northwest Side has died, possibly of natural causes. He was nearly 6.

A resident's dog found the bird, which lived near West Cortaro and North Thornydale roads, in the family's yard earlier this year. The cause of death will almost certainly never be known, scientists now say.

It's possible he died of old age because he was approaching the end of his normal six- to seven-year life span, Dennis Abbate, a State Game and Fish Department biologist, said this week.

He will be remembered as a symbol of the clash between urban growth and ecosystem needs in the Sonoran Desert.

The deceased, whose full name was Cactus Ferruginous Pygmy Owl, leaves behind two other male pygmy owls, one approaching age 5, the second about a year younger.

One of those listed as a survivor, however, has been missing since January and could also be dead, said Scott Richardson, a U.S. Fish and Wildlife Service biologist. But Richardson won't know for sure if it's gone unless it stays AWOL next spring; it does have a history of being hard to find when biologists conduct their owl census.

None of the three owls has had a mate, as each tried to make a living on reptiles, birds, mammals and insects in and around a bustling suburban area.

The latest death continues a steady decline in the endangered species' Northwest Side population, from 12 adult owls in 1996.

It also raises questions about the species' continued existence in that area. A federal team of biologists is now studying ways to enhance the state's small population of the birds by possibly moving some in from Mexico.

Like all his kind, the deceased was a tiny fellow, less than 7 inches tall and weighing about 2.5 ounces, but making a larger impression through his sharp eyes and talons. He was the color of iron rust with cream-colored streaks.

He would have nested in cavities in trees and large cacti, including saguaros, and lived in mesquite bosques, streamside woods and the desert below 4,000 feet. He needed about 280 acres of territory.

His home, the Northwest Side including unincorporated areas of Pima County, used to have the largest pygmy owl population in Arizona.

State and federal biologists say they don't know why the owls have declined there; they plan to start studying the decline this summer.

Loss and fragmentation of the pygmy owls' habitat from development and other human activity led the U.S. government to list them as endangered in 1997, causing construction delays, restrictions and legal battles, especially on the Northwest Side.

Three to four pygmy owl couples nested each year in the Northwest Side area from 1998 to 2001, according to the biologists' surveys. But none there has had baby owls since 2002.

Biologists counted a total of 18 adult pygmy owls in all of Arizona in each of the past three years.

The now-deceased male had attracted a potential mate a few years back. Their relationship was prematurely snuffed out, Abbate said, when a neighborhood cat apparently killed the female after the couple had been together 10 days.


Her feathers were found mangled. "It looked like a small animal would look when a cat got it in its mouth," Abbate said.

This January, the body of her intended mate was given to the state Game and Fish Department by the dog's owner. He had been mouthed by the dog. But he also appeared to have been dead before the dog found him because his carcass was drying up when the family saw it, Abbate said.

Authorities probably never will be able to pinpoint the cause of death because the resident who found the bird put him in the family freezer.


"They thought that was the right thing to do to preserve it. That makes sense to me," Richardson said. "But when you freeze a carcass, it causes cells to be destroyed, and it's a lot harder to figure out what happened."

One thing is clear, though: This was a pretty tough bird, given that he lived in the same home range for at least five years. He seemed to have tolerated the stresses of suburbia including new subdivisions, roads, cars and cats, Abbate said.

No memorial services are planned.

Pygmy owls on Northwest Side
● 1996: 12 adult owls, 1 nest, 2 fledglings.
● 1997: 5 adults, 1 nest, 4 fledglings.
● 1998: 7 adults, 3 nests, 11 fledglings.
● 1999: 10 adults, 4 nests, 11 fledglings.
● 2000: 10 adults, 3 nests, 11 fledglings.
● 2001: 7 adults, 3 nests, 12 fledglings.
● 2002: 7 adults, 1 nest, 2 fledglings.
● 2003: 3 adults, no nests.
● 2004: 3 adults, no nests.
● 2005: 2 adults, no nests.
Source: U.S. Fish and Wildlife Service

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