At golden eagle nests in the Los Vaqueros Watershed, six eagle chicks were hatched, raised and fledged this year, wildlife biologists at the Contra Costa Water District have confirmed.

There were no such fledglings — birds able to fly out of their nests — in 2015 and ’17 and only four in 2016, they said.

The success is a testament to regionwide prosperity for many raptors, including once near-extinct peregrine falcons and bald eagles, according to Glenn Stewart, staff and volunteers at the Santa Cruz Predatory Bird Research Group at UC Santa Cruz.

The study area for the Predatory Bird Group ranges across the Bay Area, primarily from Point Reyes National Seashore in the north, south to Monterey Bay, and east to Mount Diablo and Mount Hamilton. The group — funded by donors — operates live cams, and has a network of volunteers and a partnership with UC Santa Cruz. Led by Stewart, wildlife biologists have been able to track and verify the expansion of raptors across the region.

Bald eagles: In the 1970s, there were no bald eagles in California south of Shasta Lake, according to the group’s long-term studies. Now they estimate 40-50 nesting pairs are in the region, and some have estimated 20 mated pairs in the Bay Area.

Peregrine falcons: In the 1970s, the population was believed to be just two nesting pairs — and in 2000, the only verified peregrine nest in the Bay Area was on the roof of Oracle Corp.’s headquarters. In a scientific paper, Stewart wrote that the Bay Area now has 41 known nesting sites, and at 18 nests, researchers found 45 young.

Best raptor sites

East Bay hills: Los Vaqueros Watershed, Livermore; Maguire Peaks, Flag Rock, Sunol Regional Wilderness; Lime Ridge Open Space, Walnut Creek.

North Bay: Skaggs Island/Sonoma Creek, Napa-Sonoma Marsh Wildlife Area; Hawk Hill, Marin Headlands; Lynch Canyon Open Space, Vallejo; Pine Mountain, Marin Watershed.

Peninsula: Vicinity of off-limits Felt Lake, Stanford; Pearson-Arastradero Preserve, Palo Alto Foothills Park.

A word about Los Vaqueros

Los Vaqueros — between Livermore and Brentwood — is often treated as a local paradise. At 95 percent full, it is by far the biggest lake in the Bay Area, double the size of San Pablo, and is surrounded by 20,000 acres of watershed lands and neighboring parklands. It also has the highest sightings of raptors in the region. Steve Goodall, who has mastered photographing eagles and other wildlife at Los Vaqueros, suggests renting a boat and then (perhaps while fishing) using binoculars to scan the oaks for nests and perches. Contact: Los Vaqueros Marina, 925-371-2628, www.ccwater.com/losvaqueros.

Waterfowl still booming

Just in: The duck population for this fall’s migrations on North America flyways is estimated at 41.2 million birds, down a bit from last year, but 17 percent higher than the 60-year average, according to the annual report released last week by the U.S. Fish and Wildlife Service. In addition, of 24 goose species, eight had “significant positive trends” over the past 10 years, including an 11 percent increase for snowgeese, 8 percent for Canada geese, and 4 percent for white-fronted geese, all common in California.

By species: Mallard (counted at 9.3 million), up 17 percent above the long-term average; blue-winged teal (6.4 million), up 27 percent; gadwall (2.9 million), up 43 percent; northern shoveler (2.6 million), up 62 percent; green-winged teal (3 million), up 42 percent; redhead (1 million), up 38 percent; northern pintail (2.4 million), 40 percent below long-term average; American wigeon (2.8 million), similar to long-term average; canvasback (700,000), similar.

Moral of the story: Buy the state and federal duck stamps.

Tourists vs. bison

A small nudge: “I heard one from a National Park Service employee about an impatient driver who didn’t like having his VW Bug’s path blocked by a bison. So he drove up to it and nudged it gently to encourage it to move out of the way. The bison responded by rolling his car, with him in it, for about a quarter-mile.” — Bill Zaumen

Launched into orbit: “My father was the dentist at the Lake Hospital in Yellowstone National Park ... and he also got to watch people wheeled into the emergency room. He remembers one in particular: a guy who wanted a bison to pose against a mountain range. He kicked the bison to get it into place. The guy was wheeled into the emergency room, with a small son in attendance who exclaimed, ‘You should have seen Daddy — he went higher than the car!’” — Mike Boom

Surprise otters

Looking out my back door: Regarding the family of river otters in the Contra Costa Canal: “I spotted three otters closer to Heather Farms (in Walnut Creek), but while on a walk closer to my home, I spotted five otters, feeding on what looked like shad. I saw one with a fish in its mouth (on Walnut Road). The otters were headed upstream, toward the Willow Pass baseball fields.” — Mark J. Furlong

Alone in the outdoors

Trail friendly: Some readers may remember the letter from Ning Chang, who won a lottery to venture to the High Sierra Camps in the Yosemite Wilderness, then learned that his hiking partner was unable to go and expressed the common fear about hiking alone. Chang filed this follow-up report: “I’m happy to say that I have successfully completed the High Sierra Camp Loop in Yosemite. ... The trail was well-marked. The people were very friendly. Throughout the trip, I saw very few people on all of the trails, which were almost deserted. While the afternoon smoke was a bit of an annoyance, the solitude along the trail was a once-in-a-lifetime experience!”

How to get away

Population growth vs. a lone voice: “The whole concept of your column is so evil. You find uncrowded places and get paid to turn them into crowded places. Thanks a lot. You take the spirit of adventure and turn it into a crowded mess. I hope a hundred people turn up next time you go to your favorite little place of solitude.”

— Gary Hughes

The numbers: Since 1970, the population of California has gone from 20 million to 40 million, and in the Bay Area, from 4.6 million to nearly 8 million. At the same time, infrastructure and the number of parks and recreation sites have not grown at that pace. In turn, park studies show, 2 out of 3 trips are now within 10 miles of residents’ homes. At major parks, at least 80 percent of visits come on Fridays, Saturdays and Sundays. Pick the wrong time and place and you now can guarantee a crowd.

The answer: Venture to landmark destinations Monday through Thursday mornings, and to nonlandmark destinations on weekends. If you don’t believe how many lakes, streams, beaches, camps and trailheads have few visitors away from peak times and days, hire a pilot to fly you around the Bay Area and Northern California on a Tuesday morning and count the cars in the parking lots at parks and trailheads, and boats on the lakes.

Tom Stienstra is The Chronicle’s outdoor writer. Email: tstienstra@sfchronicle.com Twitter: @StienstraTom or Facebook