On a crisp and clear Saturday in December, 17-year-olds Lucas Stephenson and Eddie Monson circumnavigated Olema Marsh in search of as many bird species as they could find. By noon, they had clocked 60 sightings, including the ultra-rare black-and-white warbler.
The teenage duo comes to West Marin from Napa and San Francisco nearly every weekend for the area’s unmatched birding, but this weekend was special. It was the 124th Point Reyes Christmas Bird Count, held annually by the Marin chapter of the National Audubon Society in collaboration with Point Blue Conservation Science.
The boys were five hours into the count and, with five hours left of daylight, they had little time to spare. They walked, listened and looked in every direction as they spoke to the Light.
“The birding out here is just so good, other places don’t even compare,” said Mr. Monson, a third-generation birder and president of the California Young Birders Club. He stopped for a moment. “Did you hear that?”
“Sounded like a golden-crowned kinglet,” replied Mr. Stephenson, whose father is president of the Napa-Solano Audubon Society.
Mr. Stephenson’s eyes darted to the tree line over Olema Creek. He fixed his fingers in his mouth and made a high pitched “pspspsps” sound.
The boys knew the marsh had good potential for a rare bird sighting. Sandwiched by creeks, the area contains over five miles of riparian corridor—a respite for vagrants, or birds that get lost outside their breeding and wintering paths and come to temperate climates.
Each year, hundreds of birders flock to West Marin to participate in two Audubon Society bird counts: the Point Reyes count, a 15-mile-wide zone centered in Inverness, and the South Marin count, which covers Bolinas, Stinson Beach, Mount Tamalpais and much of southern Marin. The data they gather helps identify declining bird species and those that are expanding their territories.
West Marin contains several unique biomes for birds in a close radius and is often ranked in the top five zones nationally for the number of species and rarities observed. It sees high traffic from birds migrating along the Pacific Flyway, a diverse superhighway used by birds year-round for north-south travel between Alaska and Patagonia. Many birds typically seen further east also seek refuge on the coast during colder months, and vagrant birds often stop in West Marin’s hospitable landscape.
“You have everything from rocky shore and beach to freshwater marshes, big open fields, coniferous forests, riparian woodland, agricultural habitat and so much more,” said Josiah Clark, a consulting ecologist who compiles the numbers for Bolinas. “When you put that all together, it’s a heck of a lot of vegetation and water diversity.”
Though official numbers are yet to be released, officials said preliminary results showed an average overall count for Point Reyes, with 10 fewer species than last year’s 201-species count. The South Marin count had a paltry year, though it was still a huge recovery from last year, when rain made for one of the worst counts in history.
The counts yielded some rare sightings and revealed population fluctuations of important native and non-native species. Waterfoul were more plentiful than usual on Tomales Bay, numbering in the thousands, while shorebirds were pushed by king tides into crevices where they were difficult to spot.
But the king tides also provided plenty of water habitat. Five miles north of Mr. Monson and Mr. Stephenson, Bolinas birder Keith Hansen and a team of five scoured Inverness during the Christmas bird count. Standing on a turnout along Sir Francis Drake Boulevard, they gasped at what they saw on the bay: thousands of greater scaup gliding above the water toward the Giacomini Wetlands.
“I would guess there are 3,400 out there, and that would be very conservative,” Mr. Hansen said, eyes squinting through a pair of binoculars. “I don’t think I’ve seen that many birds of any species in Marin lately.”
In the day following the southern count, Mr. Clark led a hike at Tomales Point, where he spotted 68 greater yellowlegs, a shorebird most commonly found alone. Due to the high tide, dozens were squished together in one small area. “[King tides] change the way some of these birds roost and make it harder to track them,” he said. “It’s most dramatic on the coast where you have all these rocky shorebirds, which are already hard to find in southern Marin. The waves were so big and the tide was so high that we did not see a single sanderling in all of Bolinas.”
According to a 2021 study published by Audubon Canyon Ranch, waterfowl populations have dipped slightly—with some big fluctuations—since 1992, when there were 21,900 birds on the bay. That figure rose to around 29,000 in 2008, then fell to 19,000 in 2022. But some species have fared better than others. The surf scoter has declined steeply from about 6,600 to 2,300 in the past 30 years, while the greater scaup increased from 4,000 to 6,700 in the same period.
Shorebirds have declined by 66 percent since 1990, from around 16,000 birds to 5,300 now. The western sandpiper experienced the greatest decline, down 94 percent.
Most waterbirds and shorebirds are only on Tomales Bay in winter before migrating to Canada and Alaska to breed. Scott Jennings, a co-author of the article, said both face many challenges along their migration, from habitat loss to insufficient feed. “Long-term declines for most species are probably due to many factors in many locations along these paths, rather than to any single factor in one place,” he said.
Along with sanderlings, a shorebird, peregrine falcons were completely absent this year in Bolinas. Peregrine falcons were also concerningly low in the Point Reyes area, said David Wimpfheimer, a naturalist who helps to lead the count. This was puzzling, he said, because last year, Point Reyes had one of the largest counts of peregrine falcons in North America.
“We’re all a bit perplexed about that,” he said. “Back in the ‘70s, we had a very small number and then it slowly climbed back up and last year it was huge, somewhere in the mid-20s, but there were only 10 this year.”
Crow and raven sightings peaked this year in both counts, with over 500 spotted in Bolinas and Point Reyes. This is bad news for many other birds, Mr. Clark said, as these birds are responsible for more nest predation than any other avian species.
Osprey sightings have also dropped precipitously since 2008. Mr. Wimpfheimer and Jules Evens, a research associate for Point Blue Conservation Science, said the disappearance of osprey can be chalked up to the increase of predatory bald eagles, which are not native to the area. Bald eagles first showed up in the 2008 count and have increased each year since. This year, there were 22 bald eagle sightings. Meanwhile, there were just 12 osprey sightings, down from 30 in 2008. Mr. Wimpfheimer said there were more than 30 osprey nests on the Inverness Ridge and Kent and Alpine Lakes in the 1980s. There are fewer than 10 now.
“Our national symbol can be a bully and pirate, and many osprey did not want to put up with that kind of harassment,” he said.