Getting the Lead Out
This blog post by Los Angeles Zoo animal keepers was originally published internally on February 3, 2016. To learn more about California condors and how we care for them, visit the L.A. Zoo on September 1, 2018 for International Vulture Awareness Day.
California condor 360 is a 10-year-old male that hatched April 3, 2005 and was raised at the World Center for Birds of Prey in Idaho. On January 11, 2006 he was transferred to Hopper Mountain National Wildlife Refuge, where he was released that fall to the wild. He had been captured and sent to the Los Angeles Zoo two times prior (once on June 30, 2010 and again on June 20, 2012) for chelation treatment for lead poisoning. Neither of these instances was severe and he showed no physical signs of being ill. On January 6, 2015, he was found in the Bitter Creek National Wildlife Refuge flight pen very weak and wobbly, not even able to jump up to a three-foot perch.
Luckily, it’s not uncommon for these released birds, when sick, to return to areas where there is a known food and water supply. He came in weak, wobbly, and with a very large crop of food, which can be indicative of lead poisoning. His initial blood work came back with an incredibly high blood lead level of 800 µg/dL (eight parts per million). Radiographs showed a small metallic density in his ventriculus (stomach). We spent the next several days trying to get him to either cast up or pass the density, which we were almost certain was a lead fragment that was causing his blood lead levels to spike.
Not having any luck getting rid of the fragment naturally, L.A. Zoo veterinarian Dr. Stephen Klause performed abdominal surgery on January 11, 2015 and the density was successfully removed. Dr. Myra Finkelstein of UC Santa Cruz was able to screen the density on December 1, 2015 proving that the metal indeed was lead consistent with lead-based ammunition.
Condor keepers spent the next several months trying to get #360’s digestive system working. One of the many side effects of lead is paralysis of the digestive system. This is why we sometimes see lead-poisoned birds with huge crops full of food. The crop is only a storage compartment and no active digestion takes place there. The bird squeezes the crop and, bit by bit, the stored food is delivered into the stomach (ventriculus). In a severely lead-poisoned bird, the crop muscles are paralyzed so the food just sits there and doesn’t move into the stomach. Since there is no food in the stomach the bird, still hungry, keeps eating and eating. The food accumulates in the crop and rots. The rotting food irritates the crop and causes injury to it, which leads to further complications.
Condor #360 arrived at the Zoo weighing 16.7 pounds (2 to 3 pounds of crop included) and deteriorated down to 13.6 pounds at his lowest point. The normal weight for an adult male condor is 18 to 23 pounds.
After removing the rotten food from his crop and allowing some time for the crop to heal, we began to slowly feed him fresh, clean food. Fortunately, we have developed a way to move food from the crop to the stomach manually with our hands several times a day by massaging it down and out of the crop and into the stomach, allowing the bird to receive nutrition vital to its recovery process. Along with supportive care, medications, and keeping him hydrated, we were able to get him through this ordeal. He spent two months inside our condor “ICU.” He spent five months in a small outdoor cage with supplemental heat while keepers kept close observations before he could be moved into a group situation with other birds.
It wasn’t until eight months later, at the beginning of September, that we felt he was strong enough and ready to go back out to the pre-release flight pen at Bitter Creek NWR (where he came from) for an acclimation period prior to his potential release to the wild.
On Tuesday, October 20, 2015 he was released by U.S. Fish and Wildlife Service (USFWS) biologists, who report that he is doing great. Mike Clark and I were able to see him on November 18 when we went to the Bitter Creek flight pen to help USFWS biologists perform exams on 13 condors. Mike and I were up there to conduct condor handling training for the Santa Barbara Zoo keepers and veterinary technicians and keepers from the California Living Museum (CALM). Two keepers from the Oakland Zoo arrived for training on handling as well as chelation treatment on November 20-22, 2015.
Update: June 27, 2018
“A few years ago #360 went to the Los Angeles Zoo and Botanical Gardens for severe lead toxicosis. His blood-lead levels were some of the highest the Condor Recovery Program had seen for any treated individuals, and there was a great concern as to whether or not he would pull through. After a year of intensive care by the … keeper staff and the Los Angeles Zoo veterinary team, #360 was finally deemed ‘fit for release.’
“It so happened that at the same time he was to be released, a group of captive-bred condors were also set to be released into the wild. Condors that are bred in captivity need time to adjust to the wild, and are placed in an outdoor flight pen at their release site for a few months until the Condor Team determines that are showing the correct behaviors for surviving in the wild. Many times, the Condor Team will place a mentor bird, an experienced, older bird, in with the group to help them adjust to the coming social structure. For this group, it was decided that #360 would be their mentor. Not only did #360 serve in that role, he went above and beyond, feeding the youngsters and staying with several of them after he was also released. With no known parenting experience in his past, he stepped up to play dad to a group of eight young condors. Those condors are still doing well today! This year, #360 has used his incredible dad-skills to have a nest of his very own.
“Congratulations Condor #360!”
[Source: The Condor Cave]