California eagles are soaring in numbers

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California eagles are soaring in numbers

Tom Stienstra, San Francisco Chronicle

February 17, 2002

The little duck never knew it was being watched.

It was a yearling mallard, a female, and it was paddling in front of our boat, as if it was setting the pace as we trolled for trout this past week at Lake Shasta.

Suddenly, behind us and off to the east, a golden eagle appeared in the sky.

Its dark form and 7-foot wingspan were silhouetted against a gray sky. It too had spotted the duck, and emerged in silence from a forest of oak and fir set below a limestone ridge, on the hunt, peering down at that little duck.

In the next few seconds, that golden eagle banked overhead at 45 degrees, then propelled downward at full speed, on a strafing run. At the last second, the duck must have caught a glimpse of the movement in the sky. Because an instant before that eagle went for the kill, the little duck managed to bob down, disappearing underwater.

The golden eagle pulled up, hovered, circled then saw the duck pop up, this time about 40 yards away. By now the duck was on red alert status, and after two more underwater escapes, the golden eagle pulled off and headed for land, perhaps to look for a squirrel.

With apparent ease, the duck returned, and just like before, set the pace for our boat. Within seconds, we looked up, and moving into strike position was a bald eagle, with a wingspan of about 8 feet, glossy black, its head and tail feathers glistening white. Just as quickly, the duck bobbed under, and again escaped. The bald eagle veered off for shore, then took a distant perch on an old dead pine, watching every move. The duck, meanwhile, paddled off, getting some distance from us as well.

Many people now have the opportunity to experience episodes like these. There has been a seven-fold increase in eagles in the past 30 years in California, according to estimates revealed this week by a consortium of scientists on the eve of the annual midwinter count of bald eagles.

According to census numbers, there are roughly 1,000 bald eagles in California right now, with more than 500 wintering in the Klamath Basin in Modoc County, and counts of more than 10 at nine other locations in northern California. The adjacent list details where.

On national forests in California, the number of "active territories" with nesting pairs of bald eagles has increased from 30 in the 1970s to roughly 200,

"a huge increase," notes Matt Mathes at Forest Service regional headquarters in Vallejo.

In addition, there are more golden eagles within a 40-mile radius of Mount Diablo than anywhere in the world, with roughly 60 to 100 nesting sites in rural Alameda and Contra Costa counties. A nesting pair of bald eagles has also taken up residence at Del Valle Reservoir south of Livermore. Bald eagles have also been spotted at several other lakes in the Bay Area, including San Pablo Reservoir, Lafayette Reservoir, Upper San Leandro Reservoir, and Briones Reservoir.

"This is a very exciting time for eagles," said Janet Linthicum, a wildlife biologist for the Santa Cruz Predatory Bird Research Group.

She described how biologists have equipped bald eagles at Millerton Lake in the Sierra foothills east of Fresno with "satellite backpacks," and how these eagles have migrated 1,600 to 2,000 miles to Canada's Northwest Territories near Great Slave Lake, just south of the Arctic Circle. The public can follow the tracking of this migration at the Research Group's Web site.

The increase in eagle numbers is directly attributable to three elements, according to Forest Service wildlife biologists.

Scientists credit the ban of the poison DDT and its virtual purging from the environment. By the 1970s, the use of DDT had infused into the wildlife food chain, and in turn, caused the eggs of many birds (including that of eagles) to become too thin to withstand the weight of the parent bird in the nest. During nesting, the thinly-shelled eggs would thus be crushed.

Other keys are the number of reservoirs and trout plants in California, which provide habitat and food for the eagles. Mathes added that limits on recreation in the vicinity of eagle nest areas has provided undisturbed areas for successful nesting.

The long-distance migrations mean that bald eagles can occasionally show up anywhere in California where there is sufficient food (usually fish and ducks),

water (at lakes and rivers) and protection (usually forest for bald eagles, rock ledges for goldens). The result is that when you least expect it, a bald eagle can suddenly arrive and put on a show.

That's true not only for people out on adventures, but for little ducks looking over their shoulders.

Contacts:

-- Santa Cruz Predatory Bird Research Group, Long Marine Lab, UC Santa Cruz,

1156 High Street, Santa Cruz, CA 95064; (831) 459-2466; http://www..ucsc.edu/scpbrg/;

eagle cam: http://www.iws.org/.

-- Department of Fish and Game, 1416 Ninth Street, Sacramento, CA 95814; (916) 653-7664; http://www.dfg.ca.gov/, then click on endangered species.
 

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