A few weeks ago I wrote about swallows and how much fun they are to watch as they swoop and turn. And, I repeat: If I could fly like a bird that is how I would want to fly. However, soaring comes in second, and it is easy to see how it would be a welcome respite from flapping flight for large birds, especially when they migrate long distances.
Soaring is just gliding. To soar, a bird locates a rising column of air and glides on it. If the air is rising faster than the bird is gliding downward, the net result is that the bird gains altitude while doing no work. Soaring birds turn to keep inside their bubble of rising air, which results a rising spiral path. The air is rising either because it has been warmed by the sun near the ground, called a thermal, or because the wind has been deflected upward by a mountain or ridge.
Thermals can form almost anywhere over land, but the updrafts on the upwind side of the long ridges is what makes Hawk Mountain Sanctuary on the Schuylkill-Berks County line a world-famous place to watch hawks, eagles and falcons migrate south each fall.
Often when we see a bird high overhead, it is hard to see its colors against the bright sky. Fortunately, shape and the relative size of the head, wings and tail, as well as the way a bird holds its wings, provide clues that help us identify a soaring bird. But birds don’t always show their identifying profile. You have to just keep watching them, as my friend Rudy Keller says, until they turn and give away their identity.
Our most common soaring bird is the turkey vulture, which has two-toned wings; black in front and gray flight feathers. The vultures have very low wing loading (light bodies and a large wing surface) and can soar in light updrafts. This makes them a little wobbly in flight, even though they often hold their wings in a shallow V for stability.
Red-tailed hawks are also common here. Adults have the red color on the upper side of their tails, but when they soar overhead that is hard to see. When seen from below, red-tail wings are widest about halfway from their body, giving them a paddle shape, similar to a broad-winged hawk but with a bigger head and somewhat longer tail.
We also have many black vultures, especially in recent years. They can be told from other soaring birds by their short tails and white patches in the primary flight feathers. Their black heads are slightly bigger than adult turkey vultures’ red one, but watch out for young turkey vultures that have black heads too.
The two soaring birds I enjoy watching most aren’t technically raptors, though both eat flesh. The first is the raven. Ravens have become easy to find around southeastern Pennsylvania in the last few years. They have been documented as nesting birds in Schuylkill, Berks and Delaware counties. To spread in our area they had to give up their usual cliff nesting habit and nest under man-made conditions, including bridges, electric towers and quarry walls. But we now see them regularly throughout the area.
Ravens are much larger than crows. Though their flapping flight is similar to a crow’s, they soar quite a bit. When they soar it’s easier to see the large head and beak, as well as the wedge shape of their tails.
The other nonraptor that I love to watch soar is the American white pelican. White pelicans aren’t regularly seen in Pennsylvania, but one or two are spotted in the state most years. They occasionally are seen along the coast of New Jersey and Virginia. They are more common to the west, nesting in the upper Great Plains, Rocky Mountain and Great Basin regions and traveling south for the winter. With their large heads and beaks, combined with their white bodies and bold black flight feathers, they are striking to watch fly. But what makes them amazing to watch is their habit of soaring in unison.
When hawks, eagles or gulls soar upward in a thermal they do their own thing, but white pelicans soar synchronously, moving and turning together and putting on an amazing show that I never tire of watching. Look for them in late October or Early November in Texas, or midwinter in Florida.
Mike Slater is a naturalist who lives in Brecknock Township, where he is an active member of the Mengel Natural History Society of Berks County and the Muhlenberg Botanic Society of Lancaster. He is also a member of the Baird Ornithological Club. Reach him at paplantings@gmail.com.
