Until all natural food sources are free from lead-based ammunition, lead poisoning will threaten recovery of naturally sustaining populations of condors in the wild.
Seven-year-old Ventana, the oldest living wild-raised condor chick in the Central California flock, died at the Los Angeles Zoo on August 26th, where she was being treated for lead poisoning - for the fourth time.
The death occurred less than one year after Jerry Brown, the Governor of California, signed into law Assembly Bill 711, which will eventually ban the use of lead-based ammunition for wildlife hunting throughout the state, and less than two weeks away from International Vulture Awareness Day.
Known as Condor #444 to the many condor spotters who searched the skies with their binoculars, Ventana hatched from an egg laid at the Los Angeles Zoo and was raised in the wild by condor foster parents.
She spent the first six months of her life 40 feet off the ground in the cavity of a Big Sur giant redwood. Soaring on thermals, Ventana eventually left Big Sur on the Pacific coast for the mountainous Central California Pinnacles National Park.
There she paired up with Condor #340 in 2012 and in the spring of 2013 she laid an egg in one of the Pinnacles cliff cavities. Unfortunately, the egg failed to hatch.
Wild condors - only surviving on intensive care
Ventana, like nearly every surviving wild California condor was fitted with radio tags and like many she also had a GPS tag. These tags allow biologists to track the whereabouts, the movements, the behavior and the health of the condors.
Condors are normally trapped twice a year for general health checks and to test for lead poisoning and, if necessary, treat the condors for lead exposure and change transmitter batteries. The purpose of monitoring and mitigating lead exposure is to inform management and policymaking and prevent lead-related mortalities.
This past May, Ventana was trapped and tested positive for lead. She was then taken to a new facility at the Oakland Zoo where she was the first lead-poisoned bird to be treated at the zoo's new Steve and Jackie Kane Condor Recovery Center.
Before the Oakland Zoo opened this facility, the only place set up to care for seriously ill wild condors was much farther south at the Los Angeles Zoo, a time-consuming and arduous trip for a critically sick condor from Central California.
Ventana responded well to her chelation therapy - an intramuscular administration of chemicals that bind to lead so that it can be excreted from the body - and after 22 days of supportive care in captivity she was healthy enough to be released back to Pinnacles.
However, a few months later Ventana was seen acting strangely and stumbling, so she was re-captured and tests revealed high levels of lead in her blood.
Half of California's wild condors suffer from high lead levels
Ventana's predicament was not an isolated case. According to research conducted by Myra Finkelstein and her colleagues at the University of California Santa Cruz, almost 50% of the free-flying condor population in California have had blood lead levels high enough to trigger hospitalization and clinical therapy. And like Ventana, some individuals have needed numerous chelation treatments within a single year.
Some observable signs of clinical lead poisoning in condors are lethargy, a drop in dominance at the feeding stations, and paralysis of the crop / digestive system and then the legs - a particularly cruel way to die.
A poisoned animal cannot function normally in its environment, so it is more susceptible to predators. Since it cannot get or digest food, it can slowly starve to death.
The number of condor deaths would most certainly be greater if not for the intensive management (i.e. food provisioning) and treatment conducted to ensure condor survival, and prompt treatment has saved the lives of several birds. Regrettably, Ventana was not one of them.
In the final necropsy by the National Fish and Wildlife Forensics Lab, Ventana was found to be emaciated, while her bone lead level was almost double threshold levels. A small lead-bearing metal fragment was recovered from her digestive tract.
It was always hoped that Ventana would raise chicks of her own and that her chicks would represent the first generation of wild-born-and-raised condors. Now that will not happen. Sometimes the lead levels are just too high, the condor's physiological systems have been too compromised and/or the treatment comes too late. Two other condors from the Central California flock also died from lead poisoning this year.
Ventana "was special", says Kelly Sorenson, executive director of the Ventana Wildlife Society, which has been leading the effort in Central California to bring back these majestic birds from near extinction - and brought joy to many people and taught us much about condor behaviour.
"While Ventana's death is truly a disappointment," said Sorenson, "I remain optimistic that we can eventually reduce lead to reasonable levels and expand the condor range, and if we keep at it we will succeed, but the real question is, how long must we wait for success?"
60% of condor deaths down to a single cause: lead
According to Bruce Rideout, the director of the wildlife disease laboratories for San Diego Zoo Global, lead poisoning is the most important mortality factor for critically endangered, free-ranging condors and the most significant challenge to their recovery as a species. And, the numbers back him up.
According to John McCamman, the California Condor Coordinator, 237 condor deaths took place in the wild population from 1992 until the end of 2013. Of the 137 where the cause of death was determined, 51 (37%) were due to lead poisoning.
Over 60% of the adult and juvenile deaths (that is, excluding chicks and fledglings) in the wild population have been as a result of lead poisoning; a statistic that is perhaps more important considering the significant investment in time and resources required to bring a condor to adulthood and their potential for breeding.
Because condors have been known to live past the age of 50, do not breed until they are at least six years old, and raise only one chick every other year, their populations cannot withstand the mortality rates caused by this neurological toxin.
The wild condor population is only growing because of releases from captivity and intense management. "They're being held back by lead", says Sorenson. Finkelstein agrees: "The number of birds born just doesn't make up for the number of birds that die from lead posioning. That's what needs to change."
A recent study published in Conservation Biology evaluating the blood lead levels in wild condors over the past 15 years by epidemiologist Terra Kelly and her colleagues concluded that older breeding condors are most likely to be exposed to higher levels of lead - especially those that are gaining independence from food provisioning, and flying farther away from supplementary feeding sites.
Where's the lead coming from?
All scientific evidence to date overwhelmingly shows that the principal source of lead poisoning in condors is from lead-based ammunition and that lead poisoning increases during hunting season across the condors' range.
Other sources of year-round lead-based ammunition include non-game animal hunting, depredation or shooting of wildlife on private land, euthanization of farm animals, and poaching.
Part of the problem is that lead is a soft metal that fragments upon impact, leaving hundreds of small pieces in and around the wounded area of the animal. This also makes condor populations particularly susceptible to lead poisoning from lead-based ammunition because of their communal feeding behaviour.
According to the US Department of the Interior, since condors are group feeders and only one or two lead fragments or shot pellets can cause lead toxicity, just a single animal carcass or gut pile containing lead fragments or lead shot has the potential to poison several condors.
Against intense opposition, widespread media coverage and the deep pockets of the National Rifle Association, which considers the groups trying to ban lead-based ammunition "extremists", "duplicitous" and "scavengers", in October 2013 the California legislature passed Assembly Bill 711.
This law bans the use of lead-based ammunition whilst hunting wildlife throughout the state. But unfortunately it won't come into full effect until July 2019 - obviously too late for Ventana.
Can the critically endangered condor hold on until then? With each passing year more lead will enter the environment, potentially exposing many other condors as well as other scavenging birds and mammals that feed on carcasses to lead poisoning and death.
Condors (who can fly hundreds of miles a day) and other birds and mammals can also cross state lines, so a ban on lead-based ammunition that extends only as far as the state's borders is not enough.
According to Terra Kelly, until all natural food sources are free from lead-based ammunition, "lead poisoning will threaten recovery of naturally sustaining populations of condors in the wild."
For Joe Burnett, the Big Sur condor project coordinator for the Ventana Wildlife Society, it is clear that the only way to ensure survival of the California condor population is to eradicate lead-based ammunition because "the birds cannot reproduce fast enough to make up for the numbers that are dying from lead poisoning."
Hunting is not the problem
Many of the individuals and organizations who have been involved with condor conservation are not anti-hunting. They are simply anti-lead.
Rachel Wolstenholme, Condor Program Manager at Pinnacles National Park, maintains, "Hunting and ranching operations can actually provide valuable food for condors and other scavengers." However, she stresses: "Lead-based ammunition must not have been used in the operations for it to be safe to eat."
Wolstenholme is not alone in her beliefs. Christine Johnson, a professor at the University of California Davis School of Veterinary Medicine and co-author on the recent paper published in Conservation Biology that evaluated the condor blood lead levels, emphasizes:
"Hunters and ranchers who use non-lead ammunition have made an invaluable contribution to the health of scavenging wildlife by providing critically important food sources for scavengers."
There is also the very strong belief amongst many conservation groups that the way to avoid life-threatening lead poisoning and more needless deaths is not to stop hunting, but rather to try and change long-term hunting traditions and persuade all shooters, everywhere, to use non-lead ammunition now - and not wait for the July 2019 cut-off date.
In fact, the Ventana Wildlife Society believes that the literature linking lead poisoning in condors to lead from spent ammunition is so strong that they hand out free non-lead ammunition to hunters.
The ultimate goal - a lead-free environment
Dr. Andrea Goodnight, associate veterinarian at the Oakland Zoo, originally treated Ventana, and has personally seen the effects of lead poisoning from spent ammunition on other condors. No opponent of hunting per se, she is convinced that lead ammunition must be eliminated from the environment:
"We are not saying don't hunt. We are simply saying hunt responsibly by not using lead-based ammunition. Lead has been legally taken out of gasoline and paint. The military doesn't use lead, and if that isn't a huge message I don't know what is. Animals die. It happens. I know that. But we did this to Ventana.
"We as a human race did this to her. It was our fault. We were given these big brains to solve problems. And now we all have to use our big brains to solve this problem that we have created. The solution is not that complicated. It is quite simple. We have to take responsibility for this and we have to stop using lead-based ammunition now before other condors, other species fall victims to this practice.
"We need these magnificent birds. These opportunistic scavengers keep diseases down by eating rotting and putrid carrion. If valuable scavengers disappear from our ecosystem, who knows what will happen? Ultimately, this is not simply a condor issue. It's bigger than that. This is an ecosystem and a public health issue."
Like Sorenson, however, Goodnight is optimistic about the condor recovery project. Walking from her office at the Oakland Zoo's Veterinary Hospital to the isolated 900-square-foot condor recovery center where the chelation therapy is carried out on poisoned condors, Goodnight insists: "I think there is every reason to be hopeful. Everyone involved in the project has hope."
Goodnight and I look through a plate glass window separating us from Condor #411, an 8-year-old adult male from Pinnacles, transported to the center in a large modified dog crate because his blood lead levels were abnormally high.
After treatment he now seems fit and will soon be transported back to the Pinnacles. Looking at the magnificent, majestic #411, Goodnight expresses her greatest hope of all:
"The ultimate goal for all of us is that eventually there will be no more lead poisoning and we will be out of the condor recovery business. There are not very many careers where you actively try to put yourself out of a job. This is one of them."
Dawn Starin is honorary research associate at University College London. She conducts and writes about anthropological and environmental research. Her articles have been published in numerous publications including Christian Science Monitor, Daily Telegraph, The Ecologist, Index on Censorship, New Internationalist, New Statesman, The New York Times, The Times of India, and Yes!.
Author's note: As time of writing, condor #411 is once again soaring above Pinnacles after spending three weeks recovering at the center.
Wild condor-cam: By Ventana Wildlife Society.
Oakland Zoo condor-cam: to prevent the birds from socializing too much with humans and losing their natural instincts visitors to the zoo are not permitted inside the condor treatment facility. However, when condors are being treated at the Oakland Zoo they may be viewed on webcam day and night.
Also on The Ecologist:
- 'Eat lead! Condor survival versus National Rifle Association' (also by Dawn Starin)
- 'Hunting for Truth - we respond to the NRA's retraction demand' (The Ecologist has yet to receive answers from the NRA or Michel & Associates to the questions posed.)