Lead levels in condors in Arizona and Utah decline substantially

3/13/2014 | 0

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California Condor No. 87 photographed at Grand Canyon National Park in Arizona in June 2013. Photo by Susan Szeszol

Yesterday we noted a new twist in the breeding population of California Condors in Arizona and Utah: Wild-hatched adults are nesting in 2014, meaning that, in the coming months, the population could produce its first second-generation wild bird.

Today we’ve learned even better news about the Arizona-Utah flock: Recent trapping and testing of condors has revealed a substantial decrease in the percentage of birds with toxic blood-lead levels, the lowest in nearly a decade.

Just 16 percent of birds examined since September 2013 had blood-lead levels indicating extreme exposure, compared with 42 percent of birds a year ago.

Also, in the last testing season, 28 birds required lead-reducing chelation therapy, a procedure in which a condor must be confined in a pen and injected twice a day with a chemical to clear the lead from its system. This season, the number of birds treated has dropped to 11.

Biologists and wildlife officials say the decline is a significant 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.

“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.”

Condor-recovery officials say hunters’ 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 possibilities include an unseasonably mild winter and the ability of condors to forage far and wide and consume a variety of food types.

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This radiograph shows a lead object in the digestive tract of an adult male condor that died from lead poisoning in 2012. The object was removed and determined to be a .22 caliber lead bullet. Image courtesy Ventana Wildlife Society

Chris Parish, the Fund’s condor program coordinator, 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 the 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,” Parish said. “We identified a problem, proposed a reasonable solution and, most important, we asked for help. 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. They feed on wildlife and domestic livestock that have died naturally and 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.