Nature of the Lake: Ospreys

An Osprey with a fish in its claws.

One of Lake Martin’s most impressive bird species is the Osprey.

But this very large hawk often plays second-fiddle to another large Lake Martin bird of prey, the Bald Eagle, which is the darling of patriotic lake birdwatchers.

The two birds are sometimes confused because of their similar size and shape.

That’s a shame because the Osprey is a fascinating and impressive lake resident in its own right, and it is easily distinguished from a bald eagle with a little practice.

A mature Bald Eagle has an all-white head, but Ospreys have  white heads with prominent brown stripes on the sides of their faces and through their eyes.

Ospreys are brown when seen from above and have mostly-white bodies and white on their wings from below. They have  distinctive dark patches on the undersides of their wings, at their “wrists” where the wings hinge.

While eagles fly with their wings fully extended, Ospreys often bend their wings to form an “M” shape and flap their wings in a rowing motion. The wingtips of an Osprey have four “fingers,” large dark feathers that are clearly visible in flight.

Ospreys have black beaks and white-feathered legs, while Bald Eagles have yellow beaks and legs. Finally, Ospreys have distinctive dark bars on their tails unlike Bald Eagles.

A mature Osprey weighs up to 4 pounds and stands about 2 feet tall. Its wingspan can reach almost 6 feet.

These birds are unusual because they are found across the world, with subspecies found in North America, the Caribbean, and the arctic regions. Recently the Asian variety, formerly another subspecies, was upgraded to a new species status with the common name Eastern Osprey.

The American subspecies goes by the scientific name Pandion haliaetus carolinensis and has a number of common names including sea hawk, fish Eagle, fish hawk and river hawk.

Ospreys hunt by searching for fish from high in the air, then hovering above fish spotted near the surface, before diving – feet first – to snatch their meals from the water with bone-crushingly strong talons. Ospreys are the only hawk in the Americas that feed primarily on live fish, though rarely they have been known to eat other animals, such as birds, snakes, squirrels and fish carcasses.

They are very well adapted to fishing and have the ability to close their nostrils to keep water out. They also have oily plumage that keeps them from becoming waterlogged. They have reversible outer toes that help them grab fish with two toes in front and two behind, as well backward-facing scales on their talons which function as barbs to hang onto slippery fish.

After catching a fish, the Osprey maneuvers it so that the fish’s head is facing forward to make it easier to carry in flight.

The call of an Osprey is a series of whistles, sometimes described as “cheep, cheep” or “yewk, yewk.” If you get too close to a nest, you are likely to hear an agitated call that sounds like “cheereek!”

When it comes to fishing, Lake Martin’s best bassers don’t have anything on an Osprey. These birds are reported to catch fish on at least 25 percent of their attempts, sometimes approaching a 70 percent success rate. Even more impressive to human fishermen, Ospreys spend an average of 12 minutes hunting for each fish they catch. Try that with a fishing rod.

Ospreys build their nests around bodies of water – any type of water – from rivers and ponds to saltwater marshes and even around coral reefs. On Lake Martin, Ospreys are highly visible during nesting times because their nests are large structures, built primarily of sticks and lined with all sorts of materials that can be easily found around the lake such as grass, bark, vines and items they find floating in the water.

The two nests pictured in this article were photographed this year on man-made platforms situated above the lake. One, located near Camp ASCCA, is constructed year-after-year on a wooden tabletop mounted on a telephone pole and made specifically for Ospreys. The second is built on a shallow-water hazard marker directly in front of The Ridge Marina.

Nests are built in an open area with a wide, sturdy base high above the ground, which protects the eggs and young birds from predators like raccoons.

Ospreys live 7-10 years in the wild, though some have been known to reach age 25 or older. These birds reach sexual maturity at age 3-4 and typically mate for life. Males perform a “sky-dance” above nesting sites, flying steeply up, usually carrying a fish or nesting material; then, hovering several hundred feet up with tails fanned wide and talons dangling; then diving sharply while screaming and continuing this undulating flight up and down while gradually descending to the nest.

One of the few predators of Ospreys is the Bald Eagle, which has been known to raid nests and kill adult Ospreys; however, more often, instead of attacking the Osprey outright, an eagle will pester it until the Osprey drops its fish. The eagle then makes a meal of the stolen fish instead of the bird itself.

Fun Facts:

~ Ospreys are long-distance migrants, covering huge distances during their lifetimes. One Osprey was tracked flying 2,700 miles in 13 days by scientists, who recorded it flying from Martha’s Vineyard, Massachusetts, to French Guiana in South America.

~ Ospreys have been depicted on more than 50 international postage stamps.

~ The name Osprey is a common brand name for sports teams around the world in sports from football to rugby to baseball, and so is one of its common names, the Seahawks.

~ Ospreys are popular in literature around the world, from Buddhist writings to Shakespeare, the poet William Butler Yeats to the Roman writer Pliny the Elder and in Chinese poetry.

~ Osprey populations crashed from the 1950s to 1970s because of the use of the pesticide DDT, which caused its eggs to break before chicks could hatch. Since the ban on DDT, the species has rebounded strongly.