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An Assessment of the Toxicological Effects of the Ingested Copper and Tungsten-Tin-Bismuth (TTB^TM) Bullets on the California Condor (Gymnogyps californianus)

R.M. Valencia, A. Silverman, A.Z. Mason, D. Clendenen^†, R. Risebrough^‡

Department of Biological Sciences, California State University-Long Beach, 1250 Bellflower Boulevard, Long Beach, Ca. 90840, ^†California condor Recovery Program U.S. Fish and Wildlife Service Ventura, CA 93005, ^‡Bodega Bay Institute, Berkeley CA 94705.

In the early 1980’s, chemical analyses of blood sera indicated that several deaths among the remaining population of wild California Condors could be attributed to the ingestion of lead from bullet and pellet fragments in carcasses from abandoned game, shot by hunters. Lead toxicity is therefore considered to be a major hazard to the reintroduction of captive bred California Condors to the wild.

The purpose of this study was to evaluate the relative toxicity of non-lead based alternative ballistics materials on the California condor by orally administering metal fragments to a surrogate species, the turkey vulture (Cathartes aura).

Thirty turkey vultures were trapped and randomly divided in 3 groups of 10 birds. Two of the groups were fed bovine hearts containing pellets composed either of copper or a metal composite consisting of tungsten distributed in a matrix of tin-bismuth alloy (TTB^TM). Retention and movement of the pellets within the birds was monitored radiometrically each week and the administered dosage adjusted to maintain 2.3g metal/Kg body weight. The third group was not fed any pellets. Blood samples were collected from the brachial vein prior to metal exposure and then weekly for the 8 week duration of the experiment. Liver wedge biopsy samples were also collected after eight weeks of metal exposure.

No discernable toxic effects were noted with either metal. This conclusion was supported by blood chemistry analyses, histopathalogical analyses and transmission electron microscopy which showed no differences between the metal treated and control groups.

Similarly, ICP-MS analyses showed no change in copper concentration in the liver and sera. However, an increase was noted in hepatic tin concentrations from 40 ppb (mg/L) for control animals to 300 ppb in TTB^TM treated individuals. Additionally, an increase in tin concentrations in the blood from undetectable levels, prior to metal exposure, to 3.7 ppb after 6 weeks of exposure was observed in TTB^TM treated birds. A subsequent decrease in tin concentration in the sera of TTB^TM treated birds, back to control concentrations, was observed by the end of the experiment. Furthermore, ICPMS metal analysis showed high concentrations of lead (164 ppb) in the sera after 3 weeks in captivity. Sera lead levels appeared to decrease throughout captivity from 89.5 ppb after 9 weeks in captivity to 66.6 ppb after 11 weeks in captivity.

It is concluded that copper and TTB^TM can provide a non-toxic alternative to lead based munitions and that the adoption of these materials would reduce lead poisoning in animal scavengers. Most importantly, this conversion would improve the chances for the successful recovery of the California condor population by preventing lead poisoning of released captive bred condors.

(Supported by the Department of Interior, U. S. Fish and Wildlife Service, California condor Recovery Program and the Minority Biomedical Research Support grant # GM08238-11 NIH.)

TTB^TM is a patented composition and a trademark registered to Victor C. Oltrogge.

We would like to thank WCAS for performing the ICPMS metal analysis.   

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