Limited time opportunity! Catch a rare glimpse of nesting ospreys during a ride on the Seaplane ferry. The birds won’t be here much longer.
The adult ospreys have been bringing fish, the only food they eat, to their young for about a month. Their three fledglings are almost ready to start flying. Once the young birds start flying, they will hang around the nest for a week or two before they depart and have to quickly become adept at catching their own fish.
Ospreys nesting around San Francisco Bay is a relatively recent phenomenon, according to Tony Brake, a volunteer who has been monitoring ospreys around the Bay for over a decade. “There were no historical nesting records for ospreys until 1990,” said Brake.
Ospreys returned again this year to nest at Alameda Point’s Seaplane Lagoon. But midway through the rearing process, the female became the sole provider and protector of her three chicks, after the male became entangled in fishing line. Such osprey single parenting is unheard of.
Male osprey with fishing line and bobber. Credit: Phil Dauber.
Location, location, location! But for a fenced-off dilapidated navigation light stand on a jetty at the Seaplane Lagoon, ospreys would not have had a successful nesting season this year.
In late August two adult ospreys took flight from their Seaplane Lagoon perch for parts unknown with two healthy offspring. It was a welcome sight because for the past three years a series of frustrating avian soap operas featuring other ospreys and unwanted nesting attempts aboard the maritime ship Admiral Callaghan were marked with failure. Previously in 2012 they had raised one chick, the only other recorded case of osprey reproduction at Alameda Point.
Two young ospreys on June 8, 2016, at Alameda Point Seaplane Lagoon.
In early June a pair of returning ospreys looked ready for the day in their newly made nest atop a parking lot light pole at Alameda Point, but they had no chicks to attend to. The pair’s first nest this season — on a nearby ship — had been removed during construction. Their second attempt faced interference from another osprey. By June, hopes for fledglings this year had faded. An ad hoc group of osprey watchers is hoping a dedicated osprey platform can be erected at Alameda Point in a spot where competing interests and annoyances of daily commotion don’t intrude into the reproductive efforts of the ospreys.
Male osprey bringing nesting material to light pole near maritime ships at Alameda Point with female looking on.
In early March the osprey pair began building their first nest this year where they had nested last year — on a kingpost high atop the maritime ship Admiral Callaghan. The ship’s owner, the Maritime Administration (MARAD), had removed last year’s nest. This year MARAD moved quickly to stop the nest building to avoid potential delay to relocate a nest if ordered into service. “The Maritime Administration worked closely with the California Department of Fish and Wildlife on dismantling the nest and installing deterrence devices on March 19 prior to any eggs being laid,” said Alameda resident Harvey Wilson, who has been monitoring the ospreys at Alameda Point.
Crew removing osprey nesting material from kingpost on Admiral Callaghan maritime ship at Alameda Point, March 2014. Photo by Harvey Wilson.
But that removal didn’t end the ospreys’ interest in the ship, at least not for the male osprey. He soon started bringing sticks to a lower-level hoisting post on the ship. The female, on the other hand, took a liking to a light pole in the parking lot next to the wharf. After weeks of back and forth episodes of mating and nest building at both sites, the female won, and nest building started ramping up on the light pole. At one point, it appeared that the female was hunkering down in the nest, a sign that eggs had been laid and incubation had started. But soon another female osprey appeared, trying to lure the male from his duties and disturbing the composure of the female.
Female osprey bringing nesting material to nest on parking lot light pole near maritime ships at Alameda Point – May 2014.
The third osprey now seems to have moved on, and the original pair has continued to visit the nest, but the lateness of the season offers little hope that eggs will be laid again, if they ever were, this year.
Osprey with striped bass in early June 2014 near maritime ships at Alameda Point.
The appearance of ospreys at Alameda Point, first documented in 2010, is part of larger Bay Area phenomenon of ospreys beginning to nest on the shores of San Francisco Bay. Osprey first began nesting in the San Francisco Bay Area in the year 2000, having moved their nesting range further south. There are currently 24 active nests on San Francisco Bay. One theory for the ospreys’ Bayside nesting interest is a reduction of silt in the Bay, making it easier for osprey to catch fish, their primary food source. The high silt levels are a legacy of the gold mining era during which streambeds emptying into the Sacramento River were blasted with water canons to expose gold particles.Ospreys normally return to the same nest every year, but the Alameda Point pair has now used three different sites. In 2012 they successfully raised their lone chick on an old light stand on the western jetty of the Seaplane Lagoon, their regular nest for three years. For unknown reasons, they chose the heights of a maritime ship in 2013, and in 2014 a parking lot light pole.
Osprey pair on their light pole nest April 18, 2014 as nest building continued.
An ad hoc group of osprey watchers that includes members of the Golden Gate Audubon Society have been discussing with the city the possibility of erecting a permanent osprey nesting platform on the western side of the Seaplane Lagoon. “City staff has been and is willing to continue to work with interested members of the local community to potentially establish an osprey platform at Alameda Point,” said Jennifer Ott, Chief Operating Officer for Alameda Point. “The identification of an appropriate location for this platform will depend on a number of factors, including approval by the United States Fish and Wildlife Service.”In March of this year, the city of Richmond’s Public Works Department assisted with the installation of an osprey platform at Pt. Molate, which helped divert nesting efforts from a utility pole with live wires. PG&E, with extensive raptor nesting diversion experience throughout California, has offered to install a pole and nesting tub at Alameda Point for free.
City of Richmond public works employee after installation of nesting tub at Pt. Molate – March 2014. This photo and three below are by Tony Brake.
Pt. Molate nest. Photo by Tony Brake.
Pt. Molate nest. Photo by Tony Brake.
Pt. Molate nest. Photo by Tony Brake.
“It is difficult to know what the ospreys feel or how they respond or what their capacity is for all the activity that goes on around them, but this season certainly challenged them,” said Alameda wildlife biologist Leora Feeney. “Providing safe platforms for them out of busy corridors would serve everyone better.”
Female osprey arranging nesting material with male looking on.
Osprey with striped bass, maritime ship in background at Alameda Point.
Female osprey after leaving nest and headed to Enterprise Park to gather nesting material.
Female osprey leaving nest to gather nesting material.
Male osprey (right) looking at fish before giving to female.
Male osprey mating with female 2014. Female’s tail feathers visible on left.
Osprey pair deciding on whether to set up nest on light pole in parking lot at Alameda Point 2014.
Frequent roosting area for ospreys in 2014. Female with fish.
Alameda Point Environmental Report 