FILE - A pair of young peregrine falcons stare at University of California Santa Cruz biologist Glenn Stewart before being banded in their nest on the 33rd floor of the PG&E building in San Francisco, in this May 12, 2009 file photo. After decades of scrambling on the underside of California bridges to pluck endangered peregrine falcon fledglings teetering in ill-placed nests, inseminating female birds and releasing captive-raised chicks, wildlife biologists have been so successful in bringing back the powerful raptors that they now threaten Southern California�s endangered shorebird breeding sites.
After decades of scrambling on the underside of California bridges to pluck endangered peregrine falcon chicks from ill-placed nests, inseminating female birds and releasing captive-raised fledglings, wildlife biologists have been so successful in bringing back the powerful raptors that they now threaten Southern California's endangered shorebird breeding sites.
As a result, the U.S. Fish and Wildlife Service says it will no longer permit peregrine chick rescues from Bay Area bridges, a move that they concede will likely lead to fluffy chicks tumbling into the water below and drowning next spring.
"It's a paradox," said Marie Strassburger, chief of the federal agency's division of migratory birds and habitat in Sacramento. "Yes, chicks are cute. I won't deny that for a second."
But she said the loss of chicks that fledge from the nest too early is a natural part of life.
Peregrines nest high on cliffs, trees, buildings and bridges because they hunt by diving, at speeds topping 200 mph, at wild birds they like to eat. When fledging, young peregrines fly well and land poorly. On cliffs, there are plenty of easy spots for a crash landing. On buildings, they scramble back onto window sills or ledges when their first flights go awry, or they hit the sidewalk and can be carried back to their nests. But on bridges, with smooth steel or concrete supports, chicks find no perch and often just hit the water.
"We see the loss of a chick by natural causes as an educational moment as this happens in nature all the time," said Strassburger. "The peregrine falcons on the bridges in the Bay Area just happen to be in a very visible spot so the public is more aware of it."
The recovery of peregrines, and now their potential threat to other species, underscores the fragile balance of nature that biologists have struggled with in recent years: Saving bighorn sheep in Yosemite National Park meant hunting protected mountain lions; reintroducing gray wolves in the Rockies brought a backlash when ranchers complained they were killing livestock; and bringing golden eagle populations back on California's Channel Islands nearly devastated the island fox, one of the world's smallest canines.
The decision to stop saving peregrine chicks is strictly local, says U.S. Fish and Wildlife Service migratory bird specialist Alicia King at their Arlington, Virginia headquarters. She said she didn't know of any other place where this was happening, and there's no national position. She noted that in many communities the peregrines are beloved and their chicks are treasured.
"But birds sometimes nest in places that are not the best places for them to nest, and while it's hard to watch, sometimes nature has to take its course," she said.
No one is suggesting that the drowning deaths of a dozen or so chicks taken from Bay Area bridges is going to tip the entire species back into a risky situation. Nor is anyone suggesting that allowing a few birds to be saved would actually damage the dwindling population of at-risk shorebirds hundreds of miles south.
But there are two very different sentiments about how to proceed.
For wildlife biologist Glenn Stewart, who directs the University of California, Santa Cruz Predatory Bird Research Group, allowing baby birds to topple into the choppy, frigid San Francisco Bay and drown is an indefensible approach.
"Yes, peregrines are recovered, but should we let this sometimes vigorously protected and sometimes left-to-drown resource be squandered?" said Stewart, who wrote "Eye to Eye with Eagles Hawks and Falcons" published earlier this year.
And conversely, the U.S. Fish and Wildlife Service says it makes no sense to permit chick rescues in one part of California when they are busy having to trap and move them away from threatened species habitat elsewhere in the state.
Thus Stewart was informed this year, as he applied for his annual springtime permit to remove chicks, that this would be his last.
Peregrine falcons were listed under the Endangered Species Act in 1973; at the time, there were just 11 of the birds known to be living in California and about 100 nationwide. Over the next three decades, independent biologists working with federal and state researchers successfully rescued the species, largely by releasing more than 4,000 captive-raised peregrines in 28 states, but also through meticulous conservation, ranging from chick rescues to incubating and hatching eggs.
Today there are around 2,000 in California, and as many as 10,000 more across the U.S., where they've become wildly popular thanks to live, streaming webcams above their nests and annual media accounts of their rescues from New York to Portland, Ore. KathyQ, a peregrine nesting in downtown Indianapolis, has her own Facebook page.
Falcon fans from around the world log in regularly to watch peregrines perched in their nests below bridges or on ledges of tall buildings, commenting excitedly when the 1 ounce chicks hatch, and weeks later, gathering in crowds below as they attempt their first flights. In many places, the birds even have names: Diamond Lil and her mate Dapper Dan have nested on the 33rd floor of the Pacific Gas and Electric Co. building in downtown San Francisco since 2008.