Creature Feature: California Condor

Once teetering on the brink of extinction, with only 22 individuals surviving in the wild, these bald-headed gentle giants have persevered through the most brutal of trials and have emerged as one of the most beloved conservation icons. Recognized by their naked pink-orange heads, royal ruff of midnight-black feathers around the neck, and the conspicuous patagial number tags each individual has, the California Condor is a unique species of New World vulture that acts like Mother Nature’s very own recycling crew.


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A California condor at the San Diego Zoo. After their perilous decline in the 1980s, the U.S. Fish and Wildlife  Service captured the few remaining wild individuals and placed them in captive breeding programs. Researchers and geneticists at the San Diego Zoo worked together to successfully breed a number of chicks and release them back into the wild in 1992. Today, there are over 400 California condors, both in the wild and in captivity. [Source]


Gymnogyps californianus is the largest North American vulture with a wingspan of 10 feet and a weight of up to 30 pounds. Its current range is almost unrecognizable compared to its historic range: prehistorically, the “California” condor spanned from Canada to Mexico and spread throughout the country west of the Rockies. Over time, the California Condor’s range rapidly shrunk westward until these birds only persisted in a few small patches in California. After immense human effort, including captive breeding programs and legislation changes, the California Condor now has a range that consists of four main healthy populations located in Big Sur, CA, Pinnacles National Park, CA, Transverse Ranges, CA, and Grand Canyon, AZ.


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Historically, perhaps it would have been more accurate to refer to Gymnogyps californianus as the western North American Condor. Compare its historic range (top) with its current range (bottom), with condor release sites labelled with red stars. 


The cause of such rapid population decline was a lethal combination of harmful human activity and naturally fragile life history traits that made this species the near victim of extinction. The California Condor’s source of food is exclusively carrion, i.e. the rotting flesh of deceased animals. After the last major glacial period, a mass extinction of North American megafauna meant that there were fewer large terrestrial animals left to sustain healthy condor populations1. Thus, only coastal populations survived since they could scavenge of dead marine mammals that washed ashore1. While this might seem like a reliable food source, by the 18th century a rapidly expanding human population meant increased marine mammal hunting along with increased cattle ranching2. By the late 20th century, the birds were threatened by a new danger: lead poisoning. Because condors only eat dead animals, often the carcasses they consume have been shot and left behind by hunters. The condors were consuming flesh that had been poisoned by the leftover lead bullets3. This was by far the most significant killer of California Condors in the 1980s. These days, the impact of this human-mediated problem is being mitigated by medical intervention procedures such as blood chelation (the treatment of blood in order to remove lead), in addition to various legislative protective measures.


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Today, researchers can track exposure to lead by examining feather growth and estimating blood lead levels. [Source]


California Condors are, in general, a very sensitive species. They do not reach adulthood until 7 years of age, they produce only 1 egg per year, and they care for their chick for approximately 18 months. Because of the species’ highly specialized breeding ecology, it is near impossible for them to recover from any unnatural causes of population decline, such as lead poisoning or egg collecting. Although it seemed like the world’s population of California Condors was fading into oblivion, thanks to the intervention of compassionate conservationists, this species is making a slow but steady comeback. We have a lot to owe to captive breeding programs, such as the one taking place at the San Diego Zoo, which raises chicks using life-like condor puppets to avoid imprinting on humans.


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A California condor chick raised in captivity at the San Diego Zoo. These chicks are raised with puppet adult condors, so that they do not imprint on their human caretakers. 


As we move forward, a new generation of conservationists can learn from the failures and successes of such historic reintroduction programs. This will allow us to protect beautiful and invaluable species such as the California Condor by using preventative measures rather than scrambling to conduct post-mortem recovery programs for species that play an integral role in the functioning of healthy ecosystems.

[By: Roxanne Conowitch]

Roxanne Conowitch is a fourth year Wildlife & Conservation Biology undergraduate student who is particularly interested in avian behavioral ecology. She works in the UC Davis aviary, taking care of the various species of ducks that live there. When not hanging out with ducks, Roxanne is in the field gathering data for a research project that is focusing on Ash-throated Flycatcher nesting material preferences. In the past, Roxanne has had the privilege of working on Dr. John Eadie’s Wood Duck Project, studying Wood Duck breeding ecology in the Central Valley.


References:

1Emslie, S. D. (1987). Age and diet of fossil California condors in Grand Canyon, Arizona. Science237(4816), 768-770.

2Chamberlain, C. P., Waldbauer, J. R., Fox-Dobbs, K., Newsome, S. D., Koch, P. L., Smith, D. R., … & Risebrough, R. (2005). Pleistocene to recent dietary shifts in California condors. Proceedings of the National Academy of Sciences of the United States of America102(46), 16707-16711.

3Finkelstein, M. E., Doak, D. F., George, D., Burnett, J., Brandt, J., Church, M., … & Smith, D. R. (2012). Lead poisoning and the deceptive recovery of the critically endangered California condor. Proceedings of the National Academy of Sciences109(28), 11449-11454.

Additional references:

https://www.allaboutbirds.org/guide/California_Condor

https://www.popsci.com/contaminated-mammals-pose-threat-to-condor-success-story

http://institute.sandiegozoo.org/species/california-condor

https://www.fws.gov/cno/es/calcondor/CondorCount.cfm

https://defenders.org/california-condor/basic-facts

https://www.sfgate.com/g00/science/article/Plan-would-bring-majestic-California- condors-back- 10883087.php?i10c.encReferrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8%3D&i10c.u a=1&i10c.dv=13

http://earthsky.org/earth/lifeform-of-the-week-california-condors-are-making-a- comeback

Main featured image [Photo by Madison Roberts, Source]

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