OSPREY SHIFT FROM NESTING IN TREES TO ARTIFICIAL STRUCTURES IN THE SAN FRANCISCO BAY AREA, CALIFORNIA.

Abstract

Abstract This note documents changes in both substrate used for nest sites and distribution of nesting Ospreys in the San Francisco Bay area over the last 2 decades. Ospreys shifted from use of natural to artificial structures for nesting, as well as shifting nesting distribution from a fresh-water reservoir to the San Francisco Bay estuary. Changes in predator populations, prey, and availability of nest sites may be influencing these changes. The shift from use of natural to artificial structures for nest sites by Osprey mirrors a pattern observed in other western states.