Flight Control

Flight Control

A short article reporting on the Ventana Wildlife Society's efforts to test California Condors for lead exposure.


7 - 12+


Biology, Ecology, Geography, Physical Geography

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On a steep mountainside feathered with blooming yucca plants, a team of wildlife biologists prepares to capture a flock of California condors.

The biologists, who work for the nonprofit Ventana Wildlife Society (VWS), are rounding up the condors to test their blood for the presence of lead, a metal whose toxicity has been the primary cause of death among the endangered species.

These birds, native to the Big Sur area in California, have already been lured into an aviary, and been given a calf carcass to feed on.

Still, the biologists have to net the condors and bring them into a small lab for the blood test. This is no small feat, considering that California condors are the largest North American land birds, with a wingspan that exceeds the height of a professional basketball player—3 meters (9.5 feet).

Wearing gardening gloves to prevent injuries from a condor’s beak and holding an oversized net, VWS intern Ben Dudek walks through the door to the aviary. A condor in the pen flutters near the top of the enclosure like an oversized moth attracted to a giant light.

Meanwhile, VWS Senior Wildlife Biologist Joe Burnett explains his organization’s approach to the condor trap-ups, which occur twice a year. “The whole goal is not to injure the bird,” he says. “We catch them as softly as possible.”

A few minutes later, Dudek nets a condor and enlists VWS intern Johanna Dunlap and VWS wildlife biologist Mike Tyner to help carry the massive bird inside. Once in the room, the three sit down with the bird sprawled across their laps.

As the condor breathes heavily, the biologists spring into action.
With the bird restrained, Burnett takes out a syringe and draws a plastic tube’s worth of maroon blood from one of the condor’s hairless legs.

He then hands off the container to Terra Kelly and Daphne Carlson, from the University of California at Davis’ Wildlife Health Center. They’ve set up a portable lead check station in the corner of the room. The station consists of a collection of chemicals and testing equipment, as well as a machine called a tabletop lead analyzer. This machine can give a rough estimate of the lead in a condor’s bloodstream in just 180 seconds.

Ban on Lead Bullets

Kelly says that she is in the midst of a two- to three- year condor-monitoring project. “We’ll be taking blood from the birds to look at lead exposure,” she says. “We are really interested in seeing if the ban is working or not.”

The ban Kelly is referring to is a 2008 regulation prohibiting hunters from using lead bullets within the range of the California condor. Condors are scavengers that feed on decaying animal carcasses. They can intake fragments from lead bullets when feeding on animals such as deer, coyotes, and wolves, that have been shot by hunters.

Burnett explains how lead wreaks havoc on a condor. “It just paralyzes their digestive tract so they can’t digest food,” he says. “They basically starve to death.”

Lead poisoning led to the bird being listed as endangered under the Federal Endangered Species Act in 1967. Twenty years later, in 1987, the last wild condor was taken into captivity, where it joined 26 other birds.

Since then, captive breeding efforts have increased the population of the California condors. Today, there are 52 condors flying above Central California.

Two condors have died from lead poisoning since the 2008 ban.
Routine Check-Up

During the three minutes the tabletop lead analyzer takes to study the condor’s blood, Burnett examines the restrained bird like a doctor giving a patient their annual check-up. As the condor’s eyes look away, he checks the bird’s feathers and feet.

Burnett also makes sure that the condor’s numbered tag and radio transmitter are properly attached. The tag allows the biologists to know which of the 52 local birds they are dealing with. The radio transmitter allows them to monitor the condor’s movements.

A beep from the tabletop lead analyzer means the verdict has come in. “10.3 [micrograms of lead per deciliter],” Kelly says.

“Good,” Burnett responds.

While anything greater than 10 micrograms per deciliter means the condors have been exposed to more than the naturally occurring levels of lead in the environment, the biologists only take in condors that have lead levels over 20 micrograms per deciliter.

If such high levels of lead are found in their bloodstream, the condors are taken to a clinic in nearby Monterey, California, where they begin a treatment of injections that help the bird to dispel the metal. In the worst cases, the condors are rushed to the Los Angeles Zoo and Botanical Gardens for more intense treatment and monitoring.

The process moves quickly as the biologists capture condor after condor and take blood samples while doing quick physical examinations. At one point, Burnett removes an old tracking device and attaches a new one on a condor’s wing.

On most days, the VWS biologists use radio transmitters to track the condors’ movements, feeding, and roosting. They also put out stillborn calf and deer carcasses for the birds.

“We supplement feed to provide a clean food source and to provide food for younger birds who have not learned to feed yet,” Burnett says.

As the afternoon heats up, a halo of flies appears around the biologists’ heads. They capture one last condor for testing. “It’s not over yet,” Burnett says. “It’s always the last bird [that is poisoned by lead] by Murphy’s Law.”

Just three minutes later, the tabletop lead analyzer beeps for the last time that day. “7.9 [micrograms per deciliter],” Kelly calls out.

The biologists seem to breathe a collective sigh of relief. “We thought for sure we’d find one with high levels of lead today,” Burnett says, “so this is a good day.”

Fast Fact

Big Birds
An adult California condor can weigh around 10 kilograms (22 pounds) and have a wingspan of 3 meters (9.5 feet).

Fast Fact

Ventana Wildlife Society
For students interested in wildlife biology and conservation, the Ventana Wildlife Society welcomes volunteers interested in preserving the habitat of the California condor.
For more information, contact the Ventana Wildlife Society.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Stuart Thornton
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
National Geographic Society
Last Updated

October 19, 2023

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