April 14, 2003

Peregrine falcons take flight at Long Marine Lab

By Tim Stephens

Three young peregrine falcons are testing their wings this week at Long Marine Laboratory.

The young falcons were hatched by captive parents and raised in a large aviary with minimal human contact to prevent tameness toward people. Photos: Howard "Boots" McGhee

The falcons were raised in captivity and are being released to the wild by the Santa Cruz Predatory Bird Research Group (SCPBRG), which is affiliated with UCSC's Institute of Marine Sciences and based at Long Marine Lab.

Glenn Stewart, SCPBRG program manager, said the birds may remain in the area of the laboratory for a month or longer, taking food provided by the researchers, while they develop their flying and hunting skills. Visitors to the lab's Seymour Marine Discovery Center will be able to see the falcons during this time, although it is hard to predict how much time the birds will spend near the release site, Stewart said.

"In the wild, it takes about a month for them to learn to hunt for themselves and become independent from their parents," he said.

The three falcons, all males, are being released using the same methods that SCPBRG biologists have used since the 1970s to help bring the peregrine falcon back from the brink of extinction. The group has released more than 950 peregrine falcons into the wild, mostly in California. These are the first to be released at Long Marine Lab.

"We use a release method known as 'hacking,' after an old falconry method for getting young birds in shape before taking them up for hunting. The difference is that we are returning them to the wild," Stewart said. (A detailed description of hacking can be found on the SCPBRG web site.)

The release at Long Marine Lab was planned as mitigation for the disturbance of a nesting pair of wild peregrines during seismic retrofitting work on the San Francisco Bay Bridge. Caltrans contracted with SCPBRG to carry out the release, which was required under state and federal wildlife regulations.

The young falcons were hatched by captive parents and raised in a large aviary with minimal human contact to prevent tameness toward people.

When they were five weeks old, they were transferred to the release site, called a "hack box," set up on a third-floor landing of the Center for Ocean Health building at Long Marine Lab. The box, with a gravel-covered ledge, is similar to a natural eyrie. It has a hatch where food can be dropped in surreptitiously, so the birds aren't aware that they are being fed by people and don't become tame.

Glenn Stewart hopes the birds will be perching on rooftops for several weeks in the area of Long Marine Lab, where people can enjoy watching them. One of the falcons is on its perch outside the high window in the background. Photo: Tim Stephens

The falcons were held in the hack box for about a week while their flight feathers grew in. On Thursday last week, Stewart slid back the bars that covered the front of the hack box, giving the birds their first opportunity to try their wings. They could take their first flights any time in the next few days, Stewart said. A supply of fresh quail ensures that the birds will continue to associate the hack box with food as they explore their surroundings.

"They usually return to the box daily for up to six weeks for food that we secretly provide in the box," Stewart said. "My hope is that for several weeks they will be perching on rooftops and generally dominating the airspace around the lab, where people can watch and enjoy them."

It is possible that one or more of the birds will leave the area after just a few days. They might also spend most of their time out of sight, only appearing once a day for 30 seconds or so while they grab some food.

"It's very unpredictable how much time they will spend at the front of the box," Stewart said.

When SCPBRG began its work in 1975, only two nesting pairs of peregrine falcons remained in California. Peregrine populations throughout North America had been decimated by the pesticide DDT, which caused the birds to lay thin-shelled eggs that broke or dried out. In 1999, when the peregrine falcon was removed from the endangered species list, the director of the U.S. Fish and Wildlife Service gave the SCPBRG an award in recognition of its "pioneering efforts" to restore wild peregrine populations.

The group is currently engaged in a survey to quantify the current population of peregrine falcons in California. The researchers estimate that there are more than 250 breeding pairs in the state, but the last comprehensive survey was done in 1992.

"We used to be able to observe every nesting site, but there are so many now that we don't have the staff to keep track of them all," Stewart said.

The group has been recruiting a large network of volunteers throughout the state to provide information about nesting pairs of peregrine falcons. People who know of peregrine nest sites and are willing to make at least two visits to the sites this spring are encouraged to e-mail the SCPBRG. More information about the survey is available on the group's web site.

The SCPBRG is dedicated to the recovery of endangered predatory birds and applies its expertise to a wide range of bird species. The organization's work is entirely supported by foundation grants, gifts from individuals, and contracts awarded by state and federal agencies.

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