and getting better
Here’s Why:
Osprey populations have rebounded and are improving. Their recovery demonstrates the value of reducing contaminants in our environment and employing conservation measures.
Ospreys are a unique type of hawk, known for their impressive hunting techniques. They dive feet-first into the water to catch fish swimming near the surface. Thanks to their oily feathers, broad wings, and unique reversible toes, these birds of prey can effortlessly emerge from the water, often carrying a large fish in their talons. These successful hunters can make a catch 25 to 70 percent of their dives, taking just 12 minutes to fish out their meal.
Every March, Ospreys make their way to the Delaware Estuary, with their nesting season starting in April. These large birds (roughly the size of a goose) build colossal nests on top of trees, utility poles, and specially erected nesting platforms. They’re big on recycling, reusing nests, and expanding them each year as wide as 6 feet and as deep as 13 feet – about the size of your average car.
Magnificent as they are, ospreys face several challenges. Fledgling, or baby, ospreys are preyed upon by bald eagles and great horned owls, and raccoons occasionally take their eggs. Moreover, other birds of prey are known to take over osprey nests and rob them of their freshly caught fish.
Ospreys face challenges from humans as well. Historically, the osprey population in the Northeast United States faced significant declines from the 1950s through the 1970s due to exposure from DDT (a pesticide used for mosquito control) and PCBs (polychlorinated biphenyls, a man-made chemical found in industrial equipment) building up in the food chain. Ospreys became exposed to these contaminants by eating fish with chemicals in their systems. This exposure negatively affected their breeding success, with populations remaining low until the 1990s. At that time, the introduction of stricter regulations to reduce the use of these harmful contaminants. Osprey eggs in the Delaware Estuary were transported to nests in New Jersey and the Chesapeake Bay to supplement populations there.
As a result, osprey populations in the Delaware Estuary have shown significant improvement over the last few decades. Osprey recovery efforts have been so effective that these birds have been removed from the endangered species list in Delaware and Pennsylvania.
However, the threat is far from over. While stricter regulations have curtailed the use of legacy contaminants like DDT and PCBs, new types of chemicals called emerging contaminants are raising concern for their potential environmental impacts. While exposure levels to these emerging contaminants are below the thresholds currently believed to cause concern, monitoring ospreys continues to be crucial in understanding the potential long-term effects of these substances on the food chain and ecosystem.
Below are a few highlights of work to support the monitoring and management of osprey populations throughout the watershed
New Jersey Fish and Wildlife and the Conserve Wildlife Foundation of New Jersey conduct annual surveys of osprey nesting in about ten regions of the state.
Permitting coordination to mitigate impacts of permitted activities in the Commonwealth of Pennsylvania is done with the PA Game Commission via the Pennsylvania Natural Diversity Index database.
How do osprey recovery efforts contribute to the strategies and goals outlined in the Delaware Estuary Program’s Comprehensive Conservation and Management Plan?
CCMP STRATEGY W2.3: Support adaptive management and reporting of pollution reductions
This osprey indicator status report is based on research compiled in the 2022 Technical Report for the Delaware Estuary and Basin (2022 TREB). Please refer to this document for more information.
