Species: Pandion haliaetus
The last bird I spoke of was a flightless bird, the African penguin. Penguins are the only flightless aquatic birds. Today, I’ll be discussing an aquatic bird that has been seen on every continent but Antarctica: the osprey.
Pandion haliaetus is a bird of prey that often gets mistaken for a bald eagle, at least in the United States. From far below, these two birds can look very similar. Both species are large (around two feet tall or more) with wing spans of five to six feet. Ospreys and bald eagles frequent many of the same hunting grounds too: rivers, lakes, estuaries, and other coastal areas.
They way to tell an osprey from a bald eagle is by the coloring. If the birds are flying overhead, a bald eagle has a dark underside while an osprey has a white underbelly and legs. If you get close enough to see their heads, look for the dark stripe that streaks away from the eyes of the osprey.
Ospreys primarily feed on fish. They soar high above the water until they locate their prey. Then the bird drives straight for the water and hooks its talons around a fish. Pandion haliaetus have specially adapted feet that allow them to keep hold of their slippery prey: their talons are long and curved, and the soles of their feet are spiny, the better to grip their prey. After catching its prey, the osprey returns to its nest high above the ground.
Fun fact: In the US, bald eagles will often attack ospreys, trying to get the slightly smaller bird to release its fish. Once the osprey releases the fish, the bald eagle stops pursuing it and grabs the fish from the air.
P. haliaetus are migratory birds. They like to spend their winters in warmer climes, so they travel to the southern hemisphere when the northern hemisphere cools for winter, much like a lot of older humans I know.
Ospreys like to nest high in the trees or on the crags of a seashore or estuary. However, they have made use of artificial places, as well; many of their nests have been found on top of street lights and telephone poles. Often, the ospreys will return to old nests for many years.
Ospreys have one brood a year, and their nests contain two or three eggs. Seven weeks after the chicks hatch, the fledgling ospreys leave the nest to venture off on their own.
In the 1950s-1960s, the osprey populations were declining drastically. Researchers discovered that their eggs were becoming too brittle, and the osprey parents were accidentally breaking the eggs when they laid on them to keep them warm.
Studies showed that a common chemical of pesticides at the time, Dichlorodiphenyltrichloroethane (DDT), was found to be the cause of the brittle eggs, through a process called biomagnification. The process is a bit complicated to explain here; essentially, it’s a process whereby harmful chemicals build up as they travel up the food chain until they eventually become quite lethal to those at the top, such as predatory birds and humans.
Fortunately, this is not a sad tale like that of Stellar’s sea cow.
In 1962, Rachel Carson published the book Silent Spring wherein she described the effects and consequences of DDT. She made public the drastic declines of predatory birds, like the osprey and the bald eagle, and the cause of it. From Silent Spring, a movement was born, DDT was banned by the Environmental Protection Agency, and stricter regulations on pesticides were passed.
Since then, the populations of osprey and bald eagles have bounced back with vigor. Ospreys have been labeled as least concern, meaning that they are no longer threatened by extinction.
I don’t believe that I have ever seen an osprey despite living near the coast. But I wanted to share this bird with you, along with its connection to Silent Spring as a reminder that not everything is doom and gloom in the world, at least when it comes to extinction and climate change. I wanted to show this as proof that we are not too far gone, that there is still hope for the future.
The book Silent Spring saved the ospreys and bald eagles of North America. If it was done once, it can be done again.
Who knows, maybe you will be the author of the next Silent Spring that awakens the world. Or maybe you’ll be one of the readers, doing your part to persuade a government.
Just remember that not all hope is lost.
Sources and links:
Ocean: The Definitive Visual Guide by the American Museum of History
Smithsonian Nature Guide: Birds by David Burnie
https://nhpbs.org/wild/silentspring.asp <—some info on Silent Spring and DDT