BOISE, Idaho - Yearly trapping and testing of endangered California condors from Arizona and Utah flocks this season revealed a considerable decrease in the percentage of birds with toxic blood-lead levels, the lowest in nearly a decade.
"The ups and downs of lead poisoning over the years demonstrate that any single season does not make a trend, but our test results are encouraging," said Eddie Feltes, field manager for The Peregrine Fund's condor project. "If this ends up being the beginning of a trend, we hope it will continue."
Biologists and wildlife officials say the drop is a big improvement over last year, which was the second worst year on record for lead exposure and condor deaths since the birds were reintroduced to Arizona in 1996.
Test results since September show 16 percent of birds trapped and tested revealed blood-lead levels indicating extreme exposure, compared with 42 percent of birds last season.
The number of birds treated with lead-reducing chelation therapy dropped to 11 birds, compared with 28 last season.
Feltes said partners in the condor recovery effort feel hunters' majority use of non-lead ammunition and their other lead-reduction efforts may be one reason for the decrease in lead toxicity levels and mortalities. Other factors that could have influenced results include an unseasonably mild winter and the ability of condors to forage far and wide and consume a variety of food types, he said.
Chris Parish, condor program coordinator for The Peregrine Fund, said condors and other scavengers benefit from the remains of carcasses left in the field by hunters. "But our research has revealed that lead bullets can fragment into tiny pieces, sometimes spreading widely upon impact in an animal's body, thereby increasing the potential for lead exposure if lead-based ammunition was used," he said.
As a result of these and other findings, the Arizona Game and Fish Department began a program in 2005 to educate hunters on the use of non-lead ammunition to help condors. In this past hunting season, 88 percent of hunters in the condors' core range voluntarily used non-lead ammunition or took other lead-reduction efforts like removing affected gut piles from the field. Hunters in this area have supported the voluntary use of non-lead ammunition at rates greater than 80 percent for the past seven years.
"Hunters and shooters are the only ones who can solve this problem, and I believe we are well on our way. We identified a problem, proposed a reasonable solution and, most important, we asked for help," Parish said. "Change is happening, resulting in less lead available to condors and other scavengers each year, making the goal of recovery ever more possible."
Since 2002, condors have been expanding their range, becoming increasingly self-sufficient as they find wildlife and domestic livestock that died naturally and feeding on all types of large animals. In response to the condors' movement into southern Utah, the Utah Division of Wildlife Resources recently completed a second year of outreach and incentives to reduce lead exposure in that portion of the condors' range.
The recovery effort is a cooperative program by federal, state, and private partners, including The Peregrine Fund, Arizona Game and Fish Department, U.S. Fish and Wildlife Service, Arizona Strip Field Office of the Bureau of Land Management, Grand Canyon and Zion national parks, Utah Division of Wildlife Resources, and Kaibab and Dixie national forests.