Pronghorn population rises; 2nd enclosure contemplated for Kofa, YPG area

 The tiny population of the endangered Sonoran pronghorn is on the rise, and federal officials are considering establishing a second habitat for the mammals that could include Yuma Proving Ground and the Kofa National Wildlife Refuge.

   "We’ve come leaps and bounds over a short time," said Jim Atkinson, a wildlife biologist for the U.S. Fish and Wildlife Service who heads the Sonoran pronghorn recovery team on the Cabeza Prieta National Wildlife Refuge east of Yuma. "We’ve made a lot of progress."

  Six years after horrific drought pared the population of North America's fastest mammal from nearly 140 to an estimated 21, the number of animals has climbed back up to about 124.

  Nine males born in the enclosure, but kept isolated from human contact, have been released in the last two years. Another six will be put into the wild in 2009 and 10 females from this year’s fawns will be released in late 2009 or early 2010.

  Atkinson and Arizona Game and Fish biologist John Hervert believe there are about 70 animals in the wild on the refuge; another 54 of the goat-sized pronghorn are living in a square-mile captive breeding enclosure within the refuge - including 25 fawns born this year.

  Currently, pronghorn roam across the 860,000-acre Cabeza Prieta refuge, but the highly skittish animals essentially confine themselves within major barriers such as highways with barbed-wire fences. Rarely will they cross paved roads.

  Pronghorn, which resemble deer and can reach speeds of nearly 60 mph, often are mistaken for antelope but are genetically distinct. They live only in the southwestern Arizona and northern Mexico deserts.

  Atkinson said extended droughts in the pronghorn habitat between Yuma and Ajo, and Border Patrol-related activity in pursuit of illegal immigrants on the Cabeza Prieta refuge and through the Barry M. Goldwater Range, "are probably the two biggest existing threats to the herd."

  A state Game and Fish aerial survey conducted every other year to count the pronghorn population will begin Saturday, Dec. 6. Hervert said a population of about 124 is "a tremendous relief.

  "But we also know the uncertainty, the variance with weather, the gains can be almost wiped out if we don’t have rain. That’s why it’s important for us to establish more than one population so that not all of our eggs are in one basket."

  That’s why Fish and Wildlife is considering establishing a second population area. It just held two open houses to discuss the proposal.

  Officials said a herd of at least 50 pronghorn would be the minimum for a viable population.

  According to Atkinson and Hervert, two areas in Arizona would be favored. The first, bounded by Interstates 10 on the north and 8 on the south, Arizona 85 on the east and the Colorado River on the west, includes the Kofa National Wildlife Refuge, an area that pronghorn historically used, and the Yuma Proving Ground.

  The second area under consideration, encompassing the eastern portion of the Goldwater range and part of the Tohono O’odham Indian Reservation, is situated within Interstate 8 on the north, Arizona 86 on the south, Arizona 85 on the west and Tribal 15 on the east.

  The Kofa refuge site would be a natural fit, Hervert said, because Fish and Wildlife is the lead agency on the recovery.

   If the the Kofa refuge were selected, a 320-acre pen would be established, likely in the King Valley, for breeding the mammal for eventual release into the surrounding population area, said Susanna Henry, refuge manager.

  If designed like the existing pen in the Cabeza Prieta refuge, the pen would be double-fenced to provide protection from predators, Henry said. It would be maintained by employees whose responsibility would be the well-being of the pronghorn, she said, and a well would be established within the pen to provide a water source to the animals.

  She said there is a likelihood some of the pronghorn, once released from the pen, might eventually wander onto to property controlled by neighboring Yuma Proving Ground, and YPG spokesman Chuck Wullenjohn said the Army is currently examining the potential impact that the pronghorn and YPG activities might have on each other.

  "We support the idea of establishing a herd," he said, "and we're studying it now to determine how it would impact our activities. There may be an impact or there may be no impact - that's what we're studying."

  Fish and Wildlife must complete an environmental assessment compliance project associated with the National Environmental Policy Act to gain approval for establishing a second pronghorn habitat and population.

  "We’re hoping to get through it by early 2010, and would start construction on a breeding pen" then so that animals could be placed in it by late that year, Atkinson said.

  "We’re real excited about this project," Hervert said. "We’ve been thinking about it for a long time. We started looking at the habitat for the second population seven or eight years ago in earnest. We have done more than one analysis of historic habitat."

  The second breeding pen should be about a half-mile square, or about half the current enclosure’s size, "based on the number of animals we want to release into the valley," he said.

  The breeding pen could cost about $300,000, and a well another $80,000 to $90,000 for watering forage for the animals. And possibly up to $150,000 a year would be needed for biologists staffing the program.

  But Atkinson and Hervert said partner agencies, from theirs to the Defense Department, Homeland Security, the National Park Service and the BLM, have ponied up funds.