Osprey

The Western Osprey (Pandion haliaetus), or “Sea Hawk”, is the only hawk in all of North America to subsist on a diet almost entirely composed of fish. While it is still under debate if they lived here in pre-colonail times as their bones have not been found in Ohlone shellmounds, they are certainly experiencing a population boom now around the east bay, and can be easily viewed along the bay shoreline, particularly Point Molae from Spring through end of breeding season in and around their nests built on man made poles.
Hawks belong to an ecological group known as raptors, or birds of prey, meaning they are carnivorous predators that capture and feed on live prey. Osprey are the dominant birds of prey that can be spotted from Temescal Creek mouth, as San Francisco Bay is positively swimming with fish to be preyed upon. Although historically Osprey populations have been small and infrequent, numerous nests have been found by bodies of water across the Bay as of 2020. The news is bitter sweet however, as these birds are a prime example of biomagnification, or the accumulation of toxins in predators of an ecosystem. Due to mining practices during the gold rush, the Bay has accumulated tons of mercury and other toxins at its bottom that is transferred up the food chain from algae, to herbivory fish, to predators. Each tertiary level experiences a different concentration of toxins, as top predators such as the Osprey are subject to the highest. Perhaps their return is a sign that conservation efforts such as Save the Bay are successful in their efforts to reduce the amount of mercury and toxins in the Bay, however further research is necessary to provide conclusive evidence.