San Francisco Bay Osprey CameraBrought to you by Golden Gate Audubon Society
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Nesting Ospreys need our San Francisco Bay ecosystem and the surrounding watershed to be as clean, healthy, and safe as possible. This means that we all need to ensure the shoreline (read more…)
Ospreys of San Francisco Bay
Ospreys – sometimes known as “sea hawks” – are magnificent large hawks that evolved to hunt and eat fish. Their vision is over three times better than human vision so they can spot fish swimming below. The dark band around their eyes reduces glare from water. Their feet are unique among North American hawks: Rough pads on the feet help grip slippery fish, while one of their talons rotates to hold fish more aerodynamically in flight.
Ospreys build nests close to the water with materials such as sticks, moss, or seaweed. They traditionally nest on dead tree snags, but when those are not available, they often nest on human structures such as light poles, cranes, or tall platforms. In San Francisco, one Osprey pair used “caution” tape to help build their nest!
Ospreys are relatively easy to identify. Look for the white head, white breast, dark eye patch, and hooked beak. Flying overhead, their wings make a sharp M or W pattern rather than a gentle curve. Hovering over the water, they dive for their prey and then plunge their head and feet forward, grabbing the fish with their feet. You might spot an Osprey carrying a fish across the water to its chicks, to a mate sitting on the nest, or over to a perch to eat it solo.
We owe an environmental debt to Ospreys: They were one of the bird species that showed us the dangers of DDT, a toxic pesticide common in the 1950s and 60s. DDT washed into our waters and accumulated in fish and then in the Ospreys that ate them. That exposure to DDT caused Ospreys’ egg shells to become thin and break before hatching. The U.S. Environmental Protection Agency helped Ospreys survive by banning DDT in 1972. Since then, their numbers have grown from just 1,500 nesting pairs nationally in the 1970s to over 400,000 mature individuals in 2021 according to the Partners in Flight Science Committee.
San Francisco Bay has seen a dramatic growth in Osprey nests in recent years. There are no records of Osprey nesting along the Bay shore before 1990, although some nested at nearby lakes. Then in 2012, fifteen nests were found along the north part of the Bay, and in 2015 there were more than thirty nests!