California condor
Paul Wellman (file)

The California condor has long been a conundrum for even the most ardent advocates of saving endangered species, for the massive bird requires constant, expensive care from biologists and lots of undeveloped land to survive, leaving many to conclude that it’s a remnant of a bygone era. But it turns out that there’s really only one enemy standing in the way of the condor once again achieving a self-sustaining population: lead ammunition.

“Our data show that the prevalence of lead poisoning in California condors is of epidemic proportion,” concludes a sweeping study published this week by UC-Santa Cruz researcher Myra Finkelstein, “and that the principle source of lead poisoning is lead-based ammunition.”

A popular ingredient in ammo, lead becomes ingested by condors when they feed on the leftover gutpiles and carcasses of deer, boar, and other animals sought by hunters. Long considered a major hurdle for the recovery of the condor — whose population dwindled to just 22 individual animals in 1982 but today boasts nearly 400, half of which are flying free in California, Arizona, Baja, and elsewhere — the use of lead ammo was banned in 2008 throughout California’s condor country, which includes the Los Padres National Forest behind Santa Barbara.

Blood being drawn from a condor's leg
Paul Wellman

Unfortunately, this study shows that the ban is not helping enough, and that the lead threat is even worse than feared. Based on annual blood samples, about 30 percent of condors show lead exposure levels that account for significant health effects, and 20 percent of free-flying birds have high enough lead levels that they require intervention to survive. Because of that, the study confirmed what many have suspected, that “the condor’s apparent recovery is solely because of intensive ongoing management, with the only hope of achieving true recovery dependent on the elimination or substantial reduction of lead poisoning rates.” Complicating matters further is that a tiny bit of lead contamination goes a very long way, which means that unless the toxic substance is almost entirely removed from the species’ habitat, the condor will require steady care forever.

To learn a little bit more about what the study found, lead author Myra Finkelstein, who first studied toxicity in albatross but began working with condors in 2008, answered a few of my questions this week.

Is this more evidence than you expected about how dangerous lead is for condors?

Anyone who works with condors knows it is a big problem, and especially in our lab, because we get samples of all the birds that died from lead poisoning over the years. But when you put it all together into a comprehensive big picture, it was kind of surprising. We knew it was a big problem, but I didn’t totally appreciate the magnitude of the problem.

Was this study just an assessment of existing data or did you expand the reach?

This was a very comprehensive assessment. We took a multidisciplinary approach where we used monitoring data that U.S. Fish & Wildlife collects, added data that we analyze in our lab, including sublethal data, and then ran population models to understand what the effect was. Another thing we did was expand our prior data set five-fold to look at the isotopic composition for lead in condors and lead in different ammunition sources.

California condor
Paul Wellman

So is the lead ammo ban working or not?

We don’t know. We didn’t assess that. We didn’t assess anything to do with compliance. The only thing we looked at is lead exposure in condors. The only thing we can speak to is, that in the two years after the ban was implemented, condor lead exposure rates had not declined.

So even with the ammo ban, lead is still getting into the habitat?

Condors are continually and still currently exposed to lead, and they are becoming lead poisoned. One of the things we think is contributing to this is the fact that even if you have a very low carcass contamination rate, the probability that a condor will encounter a contaminated carcass is very high. Then consider the fact that condors live a long time and have to avoid contaminated carcasses for decades.

Would the complete removal of lead from the condor habitat save the species?

One of the things we examined with our population models was that, if we removed lead mortality, their population would be growing and they could potentially reach a self-sustaining population.

So you’re saying that there’s actually a chance for this species to succeed?

That’s what our study shows. It does seem like the condor might be able to make it if we are able to eliminate lead poisoning.

What’s the next step for this study?

Our hope is that this information can be used to help inform effective and efficient management decisions.


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