Lead Ban Chronicles – Is The Lead Ban Saving The Condors?

January 23, 2012

In a report a few years ago, the American Ornithologists’ Union (AOU) wrote a fairly extensive report on the state of the California condor.  In it, as many other reports have stated, the writers concluded that unless lead ammunition is completely removed from the environment, the condor program will never be a success.  But what they also said is that even if lead is abolished, the success of the condor reintroduction is a tenuous proposition.  There are simply too many factors aligned against this big bird. (You can read the whole thing here.)

A new report (that sounds an awful lot like the old reports) was recently released by the San Diego Zoo, and suggests that humans are still the biggest threat to the survival of the condor.

Scientific paper shows California condor still threatened by human activities  

A recently released scientific paper authored by San Diego Zoo Institute for Conservation Research scientists shows the leading causes of death of the endangered California condor in the wild are human influenced, with lead poisoning being the primary factor in juvenile and adult birds.

The study documents the deaths of wild California condors at all release sites—California, Arizona and Baja, California, Mexico—from the inception of the reintroduction program in October 1992 through December 2009. The study found that 70 percent (53 out of 76) of condor moralities can be attributed to human influences.   For nestlings (birds younger than 6 months of age), 73 percent of known mortalities can be attributed to the consumption of microtrash, such as bottle caps and small pieces of broken glass, plastic and metal. Lead toxicosis, from the ingestion of spent ammunition, was the most important factor in juvenile condor mortality (birds between the age of 6 months and 5 years) and was the only significant cause of death in adults (birds 6 years old and older). Eight of 23 birds that died of lead poisoning still had metal or lead fragments in their gastrointestinal tract. Condor 422 was in the wild for six months and was exposed to lead four times prior to its death.

“The most important mortality factor for the combined free-ranging populations was lead toxicosis,” states the report. “The evidence that the principal source of exposure is lead ammunition is overwhelming and includes the recovery of lead shotgun pellets and bullet fragments from the upper GI tract where lead is readily absorbed and tissue lead isotope signatures that match lead ammunition and not other sources of lead.”   In addition, the paper cites exposures to lead that coincide with deer hunting season, the condor’s foraging activity in popular hunting areas, high numbers of lead-bullet fragments in hunter-killed carcasses and lack of other lead sources in condor habitat.   “Although lead toxicosis from spent ammunition still threatens the survival of the California condor, one of our most iconic species, the good news is that solutions are available in the form of nontoxic ammunition,” said Bruce Rideout, DVM, PhD, Dipl. ACVP, San Diego Zoo Institute for Conservation Research director of wildlife disease laboratories. “We can make this a win-win situation if we choose to.”   Additional human-influenced deaths included 11 power-line collisions or electrocution. However, no fatal collisions or electrocutions have occurred since 2007, when power-pole aversion training was introduced for condors being prepared for release into the wild. During the study period, four birds died by gunshot and one by arrow. Two birds ingested zinc-core pennies, which led to zinc poisoning.

Parent feeding of microtrash to nestlings was the most important cause of death in this age class. Biologists have been clearing nest caves of trash prior to hatching and periodically throughout the nestling stage to reduce this problem. It has helped, but the cause of this behavior by adult birds remains open to speculation. One belief is the parents are feeding what they believe to be bone or mollusk-shell fragments—but is actually trash—as a calcium source for the chicks. Others suggest it is a substitute for small stones and sticks that aid digestion. Polished bone fragments are now being provided as a calcium source for adults to feed to nestlings.




5 Responses to “Lead Ban Chronicles – Is The Lead Ban Saving The Condors?”

  1. Dann on January 23rd, 2012 08:40

    The lead poisoning caused from hunter ammo story is getting old.

    We’ve had the lead-free ammo requirement in place for 3 1/2 years now and according to the DFG, we’ve had compliance approaching nearly 100%.

    If the condors are still dying, I suggest they look elsewhere, ’cause it ain’t us and I never thought it was.

  2. Tony on January 25th, 2012 09:32

    Dear Phillip,
    The human effects argument is an interesting one.

    There is important research done by Dr. Sanford Wilbur showing a) that condors possibly enjoyed a population resurgence in California back during the Spanish Rancho days when cattle roamed across Condor range in California; and b ) that condors were negatively impacted by scientific collection practices (eggs, zoological specimens, research skins and skeletons). More than 300 condors alone were taken (killed/captured) between 1850 and 1920 for research and display purposes.

    Given that the Condor Program has just spent more than $ 40 million with their “inbreeding” program to get the world population up to just under 400 (wild and captivity), Dr. Wilbur’s research offers interesting perspective.

    The current recovery program is not without its mortalities as well. Condor deaths related to condors impacting poles (blunt force trauma) and what appears to be related to veterinary problems during chelation are also part of the record.

    It will be interesting to see this latest San Diego Zoo study, if only to see if there are any omissions of sources of lead that don’t comport with the “lead ammo meme”.

    Given what happened with Condor # 132, and that the source of lead that was first attributed to ammunition was later revealed to have been a piece of lead-contaminated wood, the public would do well to remain skeptical.

  3. Jeff Mcloughlin on January 27th, 2012 10:48

    California DFG saying they have 100% compliance is a bit of a leap, don’t you think? They have 350 field officers for the entire state. While compliance within the deer zones might be good, the ability to police or verify the use of non-lead within the vast tracts of private land is impossible. I’ve heard of ranchers saying they wouldn’t waste a copper bullet on a pig. It’s unfortunately those guys that can take out a dozen condors with one lead bullet.

    I’ve seen both eagles and condors die in an ugly twitching death from ingesting fragments of lead ammunition. Senseless waste of beautiful animals. You can deny it all you want but they are dying from licking batteries or peeling off lead paint. It’s the lead bullet. No other plausible source. None. Zero.

  4. Phillip on January 27th, 2012 14:35

    It’s always dangerous when we’re talking absolutes, whether it’s 100% compliance with the lead ban or zero alternative plausible sources of lead other than ammunition.

    For what it’s worth, I agree that 100% lead ban compliance is highly unlikely. The compliance numbers come from checkpoints, and focused only on hunters. There has never, to my knowledge, been a concerted effort to police the behavior of land owners in the lead ban area, and I have no doubt whatsoever that many of them are still using lead shot and bullets on everything from squirrels and coyotes to deer and pigs. It’s happening. The thing is, how do you stop it? That’s one of the key weaknesses of the whole lead ammo ban, because it’s really not enforceable. California simply doesn’t have the resources to manage this.

    But, I also don’t believe you can rule out alternative sources of lead besides ammunition. We DO know that there are piles of stuff out there, from lead-painted scrap wood to lead-coated telegraph wire. This isn’t to say that lead ammo isn’t a source. I’ve been pretty well convinced (sorry, Tony) that the ingestion of lead fragments creates a health problem. I’m simply not convinced that the lead ammo ban will solve the problem for condors in the long run, and if not, then what was the point? A delaying action?

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