Coastal Wildlife & Native Plants
By John Marshall
Ospreys: Winged Anglers
Although once a rare site along the Gulf Coast and many other areas, ospreys are now a common occurrence in our area. Also known as fish hawks, these fish- eating birds of prey can be found anywhere there is a source of permanent water, fresh or salt.
Ospreys are found in similar habitats as bald eagles, and are sometimes mistaken for them. Bald eagles are larger and the adults have white head feathers and black bodies. Ospreys have white crowns, foreheads, necks, breasts and bellies, with black wings and backs. Separating the white feathers on the crown from those on the neck and chest is a distinctive black eye stripe. As with many other birds of prey, the females are about 20% larger than the males.
Like bald eagles, ospreys mate for life. Once a pair bonds and mates, nest construction begins. The osprey pair will return to the same nest, year after year, continuously building onto it. Older nests can reach 4 or 5 feet in diameter and weigh several hundred pounds. They prefer to build their nests in the tops of large dead trees with flattened tops, but will build on top of power poles, cell phone towers and channel markers.
Female ospreys lay 2 or 3 brown speckled eggs which incubate for about one month. The eggs hatch in the order in which they were laid, giving the oldest chick an advantage in feeding and growing first. The younger chicks often do not survive during food shortages.
After the nest is built and the eggs laid, the male spends most of his time hunting for himself, his mate and eventually, the young. He will continue this behavior until the young birds can fly and hunt for themselves.
Both osprey parents care for their young, and the chicks grow rapidly. They reach more than 70% of their adult size in just a month. After about 2 months, young ospreys are ready to leave the nest, but often return to the nest for several weeks to beg for food from their parents.
An osprey’s diet is pretty monotonous, about 99% fish. They are not particular, feeding on whatever species is most abundant. Although bald eagles will eat dead fish, ospreys prefer to take their prey live. Where ospreys and eagles share hunting grounds, eagles often “mug” the ospreys, stealing their fish.
While bald eagles swoop down over the top of the water and catch fish near the surface, ospreys plunge completely into the water from as high as 200 feet, talons out front, sometimes going under.
To help hold fish, ospreys not only have sharp talons but also have spines on the pads of their feed called “spicules”. They also have an opposable toe that can be rotated forwarded or backward, depending on the circumstances.
After taking flight the osprey will rotate its feet so there are 2 claws on each side of the fish. This helps to reposition the fish to face head forward, making it more aerodynamic in flight.
Like bald eagles and brown pelicans, ospreys fell victim to pesticides like DDT. These pesticides built up in the food chain and caused the shells of osprey eggs to weaken and break under the weight of the females during incubation.
Since these pesticides were banned in the 1970s, ospreys have made a dramatic comeback. Now these winged anglers are once again a common site along our waterways.