The osprey have returned. Have you seen them? Or more likely, have you heard them? Their high-pitched cries are hard to miss as they circle over the water, scanning for food, seeking out schools of fish dwelling near the surface.
The natural world can be appreciated on several different levels. The most basic is simple observation. It amazed me to discover that there are people who have lived in this area all their lives, yet never realized that osprey are migratory birds. You’ll miss out on the natural wonder of Kent County if you’re not paying attention. If you look, it will be apparent that the telephone perches, channel markers, and treetop nests are vacated by the osprey for most of the fall and winter. (Exercising better sense than most of us, the osprey of the Chesapeake Bay spend those months in exotic locales as far south as Costa Rica.)
They return to this area every year within a couple days of the 15th of March. Mating pairs will return to the same nesting site year after year. Over the next few weeks they’ll be busy with “spring cleaning,” shoring up or rebuilding their structures with sticks, corn stalks, or even broken fishing rods. These nests, which can exceed five feet in diameter, feature a depressed center which helps conserve heat for the eggs that will be laid in mid-April.
Osprey can be found in every continent except Antarctica, although there is no more abundant habitat than the Chesapeake Bay, home to 25% of the world’s osprey population. Their nickname, “fish hawk”, is a tribute to their exceptional skill at locating, seizing, and transporting their aquatic prey.
Some of these facts can’t be learned by observations alone. If you want to gain a fuller understanding and appreciation for what’s going on outside your window, you need to dig deeper. Ask an expert, read a book, or search the web. As a testament to that process, I did some research on osprey for this piece, and as a result understand and appreciate these birds in a more complete way.
I’d observed that osprey carry fish and sticks lengthwise, in line with their bodies. It makes sense in that there’d be less wind resistance impeding their flight. I’d heard anecdotally that they possessed some type of adaptation that allowed them to rotate their talons to hold objects in this way. It seemed like the ornithological equivalent of the opposable thumb.
In my line of work, I come across a lot of “nature facts” anecdotally. Like a juicy piece of gossip, it’s tempting to accept it as fact and pass it on. My coworker, Capt. Tom Briggs, refers to these as “factoids” that is: unverified data that may or may not be true but gets passed around regardless.
Like most members of my generation conducting research, I went to the internet to seek out confirmation of this particular factoid. I could find no mention of this osprey trait. Then I checked the excellent book Life in the Chesapeake Bay by the Lippsons. I learned many things about osprey, but there was nothing about rotating talons. Capt. Andy McCown put me in touch with his friend, Dr. Wayne Bell, who happens to be the president of the Maryland Ornithological Society. Dr. Bell was a wealth of information, telling me that osprey are considered piscivores, meaning that their diet consists mostly of fish. He told me about special barbed pads on the soles of their feet that help them grip slippery fish. While he’d only seen osprey carry their captives head first (as opposed to eagles who carry fish sideways), he couldn’t say whether that was an evolutionary adaptation or a behavioral characteristic of the species. I mentioned how carrying a fish this way would be more aerodynamic and Dr. Bell surmised that it would also assist in minimizing the ability of the fish to wriggle free. The captive fish is still very much alive in those first few minutes it’s snatched from the water. By having one foot on the head and the other on the tail, the osprey is less likely to lose its meal.
The factoid would’ve remained unconfirmed if Capt. Andy didn’t dig deep into his bookshelf to retrieve The Sibley Guide to Bird Life & Behavior, which is published by the National Audubon Society. This is the only source I came across that goes into specifics about the osprey’s toe arrangements. The usual arrangement of three toes in front and one in back is termed anisodactyly. A section on how owls capture their prey reads, “Owls’ powerful feet have outer toes that can rotate so that two toes point forward and two backward. This arrangement permits a strong, symmetrical grip on squirming prey. Owls share this anatomical feature with the Osprey and the banana-eating turacos of Africa.” Factoid becomes fact.
Now when I see an osprey making its way across the sky with a still-wet white perch held firmly in its talons, I realize that I’m seeing an animal perfectly adapted for its role in the world. To me, that’s the fascinating thing about nature, the deeper you dig, the more you will come to understand that the earth is made up of a collection of organisms flawlessly tailored to do their part at maintaining the planet’s balance. Would that we could all fill our roles so perfectly.
Libby says
Another fascinating thing that I’ve read about osprey is that the males do the fishing. Stopping on the way back to the nest, they eat the head of the fish and then take the rest to the nesting female. I’ve seen many decapitated fish in our yard (and so have my stinky dogs!) that makes me think this is true.
Chris Cerino says
Nicely done, John Mann. Another cool trait of the osprey is that when they are flushed from their nest sites and forced to fly around for extended periods of time, they will actually cool themselves off by skimming across the top of the water in mid flight. They also can be observed in territorial battles with bald eagles, which can be spectacular displays of aerial agility.
CMC