Peregrine Falcons

Return of the Peregrine Falcons Marks a Red-letter Day for Wildlife

Dangling at the end of a 250-foot rope on the sheer face of a 500-foot-high sandstone cliff, Mike Britten did his best to ignore the avian curses hurled in his direction. After all, who could blame an outraged peregrine falcon for taking exception to the invasion of her nest, high above the blue-green waters of Lake Powell?

And Britten, a National Park Service biologist, was perfectly willing to make allowances. So long as the distraught mother didn't actually take a chunk out of his back in one of those power dives that have made the peregrine falcon the world's fastest and perhaps most spectacular flier.

The unnerving tableau of maternal devotion climaxed an ambitious effort to document the heartening surge in the number of peregrines along 2,000 miles of Lake Powell shoreline and in the hidden depths of the Grand Canyon. As Britten and I watched, two biologists-turned-climbers, delivered to the cliff top by helicopter, inched down to seven nests and tagged 15 peregrine chicks in an ongoing effort to understand one of the rare success stories in the long, sad annals of vanishing wildlife.

Just two decades ago, the oncethriving peregrines seemed doomed, devastated by pesticides, harried by hunters, and pressured by habitat loss. Perched atop their particular food chain, peregrines ate birds that ate insects that ate pesticides. The peregrines concentrated the chemicals in their bodies, which led to eggshells so thin they rarely hatched. That caused a population crash, which probably pushed the number of nesting peregrines in Arizona below 20.

Now wildlife managers have logged some 150 nesting pairs, including about 65 in the Grand Canyon and 60 on the shores of Lake Powell. Experts believe the area actually harbors 200 or 300 pairs, which would give Arizona the second-largest concentration of peregrines in the United States (behind Alaska). Experts credit the peregrines' comeback in Arizona to a ban on DDT and the completion of Glen Canyon Dam in the mid-1960s. The dam set the stage for a peregrine smorgasbord of bats and birds along the shores of Lake Powell and in the Grand Canyon. The peregrines in the Canyon reaped a windfall when the dam transformed the Colorado River from muddy to clear, triggering a boom in underwater insect populations which fueled a growth in insect-eating bats and birds favored by the peregrines.

Currently the biologists want to determine if it is time to take The impact alone is usually lethal.

Even their courtships are generally conducted in midair, aerobatic nuptials which last for life.

The nest study has revealed that most of the lakeside peregrines raise two or three chicks a year, which is fortunate since three-quarters of the fledglings die in their first year.

Biologists hope the banding of the young by Pinnock's team will reveal whether the lakeside peregrines migrate to Mexico and South America or remain in the area year-round.

In the meantime, Pinnock's group has the inestimable satisfaction of actually laying eyes on the fledglings to which they have devoted so many hours.

Perched on a ledge at the edge of a cliff, Mike Britten cradled one chick tenderly on his lap while the ground-based watchers peered anxiously through high-powered binoculars. The mother peregrine hovered just above the heads of the climbers, screeching falcon invectives. The father, high above the mesa top, folded his wings and flashed past the cliff face at a dizzying speed.

Unflappable, Britten carefully held up the gawky, fluffy chick, which looked for all the world like a Jim Hensen muppet.

The complex and triumphant $38,000 team effort that Mike Britten participated in was orchestrated by Jamaicanborn Clive Pinnock, a Park Service biologist whose ready laughter and tint of island accent impart an air of playful adventure. His parents wanted him to be a banker or a lawyer, but he couldn't shake his gnawing obsession with the wild world.

Pinnock spent six months puttering along hundreds of miles of lake channel with a good-natured team of coworkers searching for hidden nests, most tucked into cracks high on cliff faces.

Streamlined and fearless, peregrine falcons hunt entirely in the air, plunging like feathered missiles in dives of breathtaking speed. Then they pull up at the last possible instant, striking their prey with long legs equipped with biological shock absorbers.

Down on the beach, a great and decidedly unscientific "ohhhhhhhhhhh" swept the little gaggle of biologists, eyes stuck to binoculars like a covey of proud fathers peering through the glass of a hospital nursery.