WESPEN Online Order Form print this page
US Fish & Wildlife Service FieldNotes

PACIFIC SOUTHWEST REGION: Review Finds Lead Exposure Biggest Threat to California Condors

Region 8, September 4, 2013
California condor.
California condor. - Photo Credit: n/a
A pair of California condors ride currents of warm air above Bitter Creek National Wildlife Refuge.
A pair of California condors ride currents of warm air above Bitter Creek National Wildlife Refuge. - Photo Credit: n/a

By John McCamman
Back in 1975, Service director Lynn Greenwalt signed the first recovery plan authorized under the newly enacted Endangered Species act. That plan addressed the rapidly declining population of California condors, about 60 in number at that time.

 

In June, Pacific Southwest Regional Director Ren Lohoefener signed the first five-year status review for condors. In the intervening years, the population of condors declined to 22 birds in the wild in 1982 and was extirpated from the wild in 1987. Bred in captivity, condors were reintroduced into the wild in 1992.

There are now 235 California condors flying freely in the wild with a total population of more than 400. Four captive-breeding facilities propagate condors, which are released at five sites from central California down to Baja California and east to the vermilion Cliffs in northern Arizona. Most significantly, there are now 35 wild-fledged chicks that are the products of natural reproduction in the wild or were captive-bred eggs substituted for unsuccessful wild eggs just before hatching.

The heart of the five-year review considers 13 threats to the condors, including climate change, lead poisoning, the residual effects of DDT exposure, disease, habitat loss and habituation.

Lead exposure from the consumption of carrion containing lead fragments from spent shot or ammunition is the biggest cause of death in the population — twice as big as the next biggest cause of mortality, predation. It’s also the largest impediment to condor recovery. One of the criteria defining “recovery” is a self-sustaining population. The population of condors is not self-sustaining as long as lead continues to be the factor that it is today.
The effort to recover the California condor is not hopeless. The birds have overcome huge obstacles before.

If lead mortality were eliminated as a factor, the population would increase without the existing captive-breeding programs. But if captive breeding and releases as well as testing and treatment for lead poisoning ended, the condor population would decline precipitously. Estimates suggest it could result in a return in the wild to 22 birds in as few as 11 years.

Every year and sometimes more often, each wild condor is captured and tested for blood lead levels, inoculated for West Nile virus, evaluated for physical health and re-released into the wild. Depending on the population of birds and the time of year, about 35 percent of the birds tested historically have blood lead levels greater than background exposure, and about 20 percent require hospitalization and treatment. Without these extraordinary measures, even greater mortality in the population could be expected.

The effort to recover the California condor is not hopeless. The birds have overcome huge obstacles before. in the first years of the release program (1992–1994) four of the eight birds released died from interaction with power poles and lines — either electrocution or impact trauma. Following evaluation of condor behavior, biologists created a power pole aversion training program to dissuade captive-reared birds from using power poles as roosts. The last condor death from power poles or lines occurred in 2007.

Similarly, adult condors were found to be feeding their chicks micro-trash—little bits of glass, plastic and metal. Eight chicks in one population died over the course of several years from ingesting micro-trash. as a result, a “nest guarding” project was developed that consists of biologists checking each chick’s gut for micro-trash, cleaning nests and using volunteers to monitor nests and clean up areas where trash collects along roadways and picnic areas in the range of condors. Some injury from micro-trash in young birds still occurs, but none has died as a result of micro-trash since 2009.
States are taking two approaches to lead poisoning, both of which tend to reduce the amount of lead introduced into the environment.

Arizona developed an aggressive voluntary program to urge hunters and shooters to use non-toxic ammunition when hunting animals in the condor range. Measures include hunter outreach, coupon redemption programs to provide non-toxic ammunition and a “gutpile” raffle for turning in lead shot offal. As the Arizona condor population expanded into southern Utah, that state also developed outreach and coupon programs, based in part on a grant provided by the Service.

In 2007, the California legislature passed the Ridley-Tree Condor Protection act, which prohibits the use of lead ammunition for big game hunting in the range of condors as defined in the act. Legislation is currently being considered to expand that prohibition statewide.

The five-year review of the California condor recommends the establishment of a contaminants work group as part of the recovery program to advise the Service about how to reduce the harm done by lead in the environment. The report also encourages additional work with the states and federal agencies to educate shooting sports enthusiasts and hunters concerning the effects of ingested lead ammunition.

There is a light at the end of the 35-year recovery effort for California condors. By addressing the primary cause of adult mortality — ingested spent lead ammunition –a future with a downlisted and perhaps even recovered California condor is possible.
______________________________

John McCamman is the California Condor Recovery Coordinator for the USFWS Pacific Southwest Region.

Contact Info: Scott Flaherty, , Scott_Flaherty@fws.gov