Ospreys in San Francisco Bay

The last decade has seen a remarkably rapid expansion of nesting Ospreys along the San Francisco Bay shoreline. The first record of an Osprey nest was on the Mare Island Strait in Vallejo in 1990. Beginning in 2003, the number of nests began a steady climb and expansion southward. In 2012, a census of Osprey nests was launched and found 15 successful nests producing 30 fledglings. By 2016 a total of 42 Osprey pairs were observed, with 26 successful nests producing 51 fledglings. Nests are concentrated mostly along the Mare Island Strait and the Richmond shoreline. Nearly all of the nests were built on human-made structures, such as light towers, cranes, and utility poles. Many of these are on derelict structures that may collapse or be removed, presenting a significant conservation challenge. A positive development is that in 2016, nine nests were on artificial platforms or modified utility poles.

Speaker: Tony Brake, UC San Francisco, retired.