Migration on the Watershed

It's migration season. The Peninsula Watershed can be a good place to see a few or more colorful birds that aren't usually around the rest of the year.  

September through early October is peak migration season here in the Bay Area for multiple species of birds passing through on their way south from their northern breeding ranges to the warmer wintering grounds.  

Flying long distances in a single day or night, many will stop for a few days at various woodsy Bay Area spots to refuel for the next leg of the journey. Some species glean insects from tree leaves or bark, while others dart out from a perch to catch flying prey in the air.  

The abundance of insect life, native trees and other greenery makes the watershed an attractive rest area for birds on the move. If you're out on the trail, here are some typical western migrants that you might spot before they move on. 

Photos, top to bottom:  Yellow warbler; Black-throated gray warbler, Western tanager; Pacific slope flycatcher 

Trail Update: Temporary Closure of San Andreas Trail September 26 – 29

The paved portion of the San Andreas Trail, between Larkspur Drive and San Bruno Avenue, will be closed from Tuesday, September 26, through Friday, September 29 for a pipeline repair.  

Cyclists should use alternate routes during that period.    

Bald Eagle Report: 2017

The breeding pair of Bald eagles returned to the watershed to nest and reproduce again this year—though this time it was an only chick. 

It was the fifth year in a row that the pair had nested here--after a more than 100-year absence of the species from  San Mateo County. 

Though the young eaglet won’t be returning to the nest, it will continue to hunt in and near the watershed for another few months. It will keep its uniform brownish mottled color before acquiring the distinctive white head at full maturity in four years.    

  

Bald eagles mate for life, and—because they can live up to 30 years in the wild—chances are that one or more of our pair's progeny will return to the watershed too, when ready to nest and reproduce.  

  

Update: Last week's San Francisco rare bird alert reported “a juvenile Bald eagle soaring with Peregrine Falcon and Red-shouldered Hawk” above Lake Merced. Could it have been ours, checking out the neighboring terrain? 

Keep watching.  

Clearing Away for Wetland and Native Woods

People have been asking about the tree clearing along the reservoir just to the north of Highway 92. 

The approximately 80 non-native, invasive trees are being removed to restore a stretch of natural wetland that over time will again nurture and sustain water- and shoreline-dwelling wildlife. We’ll also bring back several acres of adjacent native grassland. 

Starting next week, you’ll also be able to see another tree-clearing project from Highway 280 near Trousdale.  We’ll be removing mostly eucalyptus trees, and replacing them with historic native grasses and Coastal oak woodland. 

Threatened California red-legged frog.

The work at both sites is part of the Peninsula Watershed Habitat Restoration Program to bring back native environments—and the plant and wildlife communities that depend on them—at different locales throughout the watershed. The SFPUC will maintain the new plantings and monitor their performance for up to 10 years.

The 23,000-acre Peninsula Watershed is home to a diversity of native California plants, insects, birds, reptiles, amphibians, and animals, including the highest concentration of rare, threatened or endangered species in the nine-county Bay Area.  The watershed is also designated a State Fish and Game Refuge. 

The Jepson Laurel: Centuries-Old Natural Monument Marks Sawyer Camp Trail Midpoint

The Jepson Laurel, known to be at least 600 years old, marks the Sawyer Camp Trail midpoint. At 55 feet in height, and some 22 feet around, it’s the largest laurel in California. 

It stands just north of where one Leander Sawyer kept an inn called Sawyer Camp in the 1850s and ‘60s. The establishment provided lodging for horsemen and wagons, as well as food for daytime picnickers. Old-timers said that Sawyer and his wife Sophia lived nearby in an adobe cottage close to a natural spring. Sawyer also grazed cattle in the area to control the brush and maintain access for incoming wagons. Today nothing remains of either the camp or the Sawyer dwelling.

The Jepson Laurel stays on, monitored and safeguarded by our natural resources staff. It is named after distinguished  UC Berkeley early botanist Willis Linn Jepson.

Peninsula Watershed Photo Friday - Stone Dam

For this Photo Friday, we thought we’d highlight one of our lesser known dams in the Peninsula Crystal Springs Watershed – Stone Dam.

This small dam was built in 1871 approximately two miles away from Pilarcitos Dam (which was constructed in 1866).

Spring Valley Water Company constructed Stone Dam to take advantage of the lower Pilarcitos Creek Watershed. Water impounded at Stone Dam on San Mateo Creek impounds about 5 million gallons of water (in contrast to nearby Pilarcitos Reservoir which can store 1 billion gallons of water).

Happy Friday!

Sightings on the Watershed

Two Double-crested cormorants sun their spread wings to dry during a late summer afternoon on the San Andreas Reservoir. The pastime can be a common site around the watershed. 

Since the black seabirds are at home in both salt water and fresh, the watershed reservoirs provide ample small fish for food. During the spring breeding season, they’ll display the tufted crests they’re named for.