Flight of the Condors: Expanding Their Range

Condor #625, a five year old male, flew over the Blue Ridge NWR on May 1, 2016, in the first documented flight to the refuge. Credit: USFWS

By Jon Myatt
September 7, 2016

California condors are expanding their territory, which is a significant milestone in their recovery, according to biologists monitoring the species.

Two California condors wearing GPS transmitters flew over the Blue Ridge National Wildlife Refuge just outside the western edge of Sequoia National Forest in May 2016. Condor #625, a five-year-old male, flew over the refuge on May 1, and Condor #648 followed two weeks later.

U.S Fish and Wildlife Service biologists say these flights represent the first documented presence of condors on the refuge since they were reintroduced to the wild in 1992 at Hopper Mountain National Wildlife Refuge, 125 miles south.

Condor #648, a four year old female, following the path of condor #625,  flew over Blue Ridge NWR on May 16, 2016. Credit: USFWS

“The flights over Blue Ridge National Wildlife Refuge is an important indication that as the condor population continues to grow they will continue to recolonize more and more of their former habitat,” said Joseph Brandt, supervisory biologist and leader of the California Condor Recovery Program field team.

“Condors are North America’s largest terrestrial bird, capable of flying over 200 miles in a single day, so their ability to soar such great distances means a single condor can frequent the entire annual range of the population in just a few days,” he said.

Condor activity over Blue Ridge NWR. This map shows
the GPS tracking data from the two flights over Blue
Ridge NWR in May 2016. Credit: Joseph Brandt/USFWS

Blue Ridge NWR, the smallest refuge of the Hopper Mountain Complex, is located in the foothills of the western Sierras. The refuge was established in 1982, when there were only 22 condors left in the world, because of its importance as a condor roosting site. In 1987 all remaining condors were brought into captivity as part of a Service-managed captive breeding program at San Diego Safari Park and the Los Angeles Zoo.

From 1987 until 1992, when the first condors were released, there were no condors in the wild. But since their reintroduction in 1992, the population of condors monitored and managed by the Hopper Mountain National Wildlife Refuge Complex has grown in size and distribution, according to Brandt.

His field team monitors the present flock of condors using modern technology to track the birds’ movements and habitat use. Biologists attach GPS transmitters to a subset of the Hopper Mountain Complex condor population. These GPS transmitters provide location, elevation and flight speed every 2 to 15 minutes for the condor wearing the transmitter.

The team interprets data from these transmitters to identify behaviors such as nesting, feeding, and roosting. The transmitters have been essential in documenting the range expansion of the flock, explained Brandt.

Condor 625 with GPS transmitter. Credit: USFWS

“Condors inhabit such a large area that the most efficient way to understand their day to day movements and identify the areas that they are re-colonizing is by using this technology,” he said.

“The range expansion of condors is best illustrated by mapping data from the GPS transmitters they carry,” he explained. “In the coming years we expect more condors to forage in the foothills of the Sierras and return permanently to the roosts located on the Blue Ridge refuge.”

“We are also currently working with researchers from the USGS Forest and Rangeland Ecosystem Science Center and West Virginia University to model condor flight patterns in different types of topography and weather conditions,” he said. “This will improve our understanding of the potential risk that wind turbines pose to condors.”

Condor population range expansion from 2005-2015. The purple polygons above encompass all condor GPS transmitter locations for the corresponding years. As the population has grown so too has the area of condor activity. Credit: Joseph Brandt/USFWS

As the flock of condors continues to grow in number “their range will also continue to expand,” said Brandt. “In ten years I think we can expect condors to be nesting in the Giant Sequoias and cliffs the southern Sierras. The southern flock is also likely to merge with the central California flock managed by the Pinnacles National Park and the Ventana Wildlife Society.”

Condor 625 as a juvenile in December 2014. Credit: USFWS

Condor 648 as a juvenile in October 2014. Credit: USFWS

The field team’s data has shown that both of the southern and central California flocks have begun to recolonize the habitat in Santa Barbara and San Luis Obispo Counties, intermingling more and more.

“This will eventually lead to the two flocks merging into a single population,” said Brandt. “In twenty years we may have one large population of condors across all of California and into Oregon, depending on what happens with the current efforts planned by the Yurok Tribe and Redwood National Park to release condor in Northern Calif.”

The Hopper Mountain National Wildlife Refuge Complex recently released their 2015 annual report, which can be found on the Pacific Southwest Region’s Condor Recovery Program website here and on the Bitter Creek National Wildlife Refuge website here.

Jon Myatt is the digital communications manager for the Pacific Southwest Region, located in Sacramento, California.