Rapt in sight of osprey

If you wanted a hawkish herald of spring, you couldn’t do better than the March arrival of ospreys to the lakes and rivers of North Idaho. Spring officially begins March 20; average arrival date for the first osprey of the season to Kootenai County is March 20.

Birder or not, I’m sure you know the osprey. When I moved to Coeur d’Alene many years ago, it was the first bird that caught my attention. Having lived the previous six years in the desert, an osprey was a thrilling novelty – to me.

That first summer, other guests at a lakeside party I was attending took absolutely no notice of occupied nests and active fishing going on nearby. Ospreys were too mundane to be noticed, it seemed. Everyone I mentioned my excitement to acknowledged how cool the birds were, but their expressions told me they took them for granted.

Since then, North Idaho winters have seemed especially bleak whenever I have spied an abandoned osprey nest atop a pole near some open water – especially when the nest is full of snow. And after especially severe winters, such as we’ve had this year, those nests don’t have long to thaw before ospreys begin to return.

It is the older, established birds that first arrive to stake claim to their untidy pile of sticks and flotsam from previous years. No matter how large the nest has become, there is reason each year to add to the heap until it becomes so large that gravity or weather eventually brings it down.

My second summer here I discovered the plastic owls attached to power poles along Thompson Lake that had been placed in a vain attempt to keep ospreys away from the dangers of a fully electrical home. One especially large nest so surrounded an owl decoy that only its head could be seen jutting from the debris.

These nest constructions become so massive that not only do ospreys call them home, but other bird species may nest in them as well. Starlings are a common example and can often be seen exiting some hole in the side of the jumble.

Fortunate for starlings, ospreys are pretty true to their other name: fish hawk. Although remains of snakes, muskrats and turtles have been found in osprey nests, fish are their primary diet, and preferably fish in the 4- to 12-inch range. Larger fish will be taken, though, if not too large to be hoisted aloft.

Whether the prey is small or large, the performance of a fishing osprey is a wonder. More successful than most of their human competitors, and no less patient, an osprey will land a fish on more than half of its attempts. For this purpose, it is uniquely endowed in terms of eyesight, wings and, especially, feet.

An osprey eye is looking for a fish no deeper than several feet below the surface. Anything targeted underwater, however, requires a mathematical calculation correcting for refraction of light through water. Osprey eyes make such an adjustment.

Once spotted, usually from 50 to 150 feet up, the bird must often wait for the fish to rise within striking range. Osprey wings are built to hover in such circumstances. Unlike the wings of any other raptor, though, osprey wings are angled and crooked, more along the lines of a gull’s wings.

Once the fish is within reach, the osprey folds its wings and dives straight down for the spot its eyes have determined the fish will actually be once the bird breaks the water’s surface.

Where a fishing eagle will slap at the water as it passes over a fish on the surface, an osprey dives head first, with its wings pulled back behind its tail. At the last moment before impact, its feet shoot out ahead of its head. The osprey hits the water talons followed by beak, often fully submerging for several seconds.

When talons contact fish, they snap shut, the outermost toe rotating back, in a uniquely owllike fashion, so that two extra-long, curved spikes puncture on each side of the fish. Pads of the osprey’s feet are covered with sharp spicules that also help anchor the slippery, squirming victim. Both feet, eight toes, clamp the fish’s body, one foot ahead of the other. In one swift maneuver, the fish is oriented head first for its ride to its doom.

As the osprey exits the water, propelled by one or two powerful thrusts of its wings, it hesitates momentarily midair and vigorously shakes the water from its feathers. The fish may then be taken to a perch or a nest to be swallowed whole, if not too large, or torn apart.

On migration, ospreys have been seen miles from open water, traveling with forward-facing fish in their grasp. Hawk-watchers who record yearly southern migrations of raptors note this as “packing a lunch.”

Not only have ospreys found a good living in the job they do so well, but they have also discovered the secret to a successful long-term relationship.

A breeding pair from the Columbia River was monitored via satellite transmitters as they migrated. Typical of the species, the pair left their nest site each fall at different times, often weeks apart, and wintered 200 miles apart on Mexico’s western coast. Having been away from each other for seven months, they reunited each spring at the same nest to raise another family. Sounds like a plan to me.

Giving additional meaning to the concept of “snow birds,” it was also determined that ospreys, after spending their summer in Pacific Northwest locales such as Lake Coeur d’Alene, winter along the southern Mexican and Central American Pacific coasts. Again, sounds like a plan to me.

I have referred several times to ospreys as raptors because they are closely related to more traditional birds of prey such as broad-winged, soaring-adapted red-tailed and rough-legged hawks – buteos; short-winged, long-tailed bird-hunting hawks – accipiters; long and thin-winged, owl-like hawks – harriers; dainty, insect- and snail-eating hawks – kites; and large, bulky, only distantly related to each other, hawks – bald and golden eagles.

All these birds – 24 breeding species in the United States and Canada – are a bit removed from falcons, which are in a separate family, and are distantly removed from two other groups correctly considered birds of prey, but not so correctly called raptors – owls and shrikes. Some even consider vultures to be in this group, but they are more closely related to storks than to hawks.

Until 1982, ospreys too were in their own family, separating them an equal distance from hawks as hawks are from falcons. This question of relationships is still being debated. Suffice it to say there is a sizeable evolutionary gap between ospreys and hawks and eagles – ospreys are unique among the raptors.

And it’s to our good fortune that the uniquenesses of this bird make it so well adapted to our unique environment among the lakes and rivers of North Idaho. Spring will arrive in 12 days, and with it will come the ospreys, hopefully bringing some of their tropical winter weather with them.