'Osprey over number three, just above the horizon,' the spotter shouted out to everyone. Showing its classic 'M-shape,' wingspan, the migrating raptor was past me before I could even get a good look at it through my binoculars. I thought I saw it for moment, but the spot in my glasses turned out to be a migrating Monarch butterfly! It was early September, and my wife and I were sitting on the north lookout of the world famous Hawk Mountain Sanctuary. It was a perfect day for hawk watching. The air temperature was cool, and a brisk northwest wind was pushing the raptors quickly along the ridge. They had already started their long journey south.
Each fall, in many locations around the world, including several in Pennsylvania, thousands of raptors, (also known as birds of prey), and protected by law, migrate south to more temperate wintering grounds. If you're at the right place at the right time, and the winds are from the northwest, it can be an awesome event to witness. The possibility of seeing hundreds of soaring hawks, eagles, falcons, osprey or vultures flapping and gliding overhead is well worth it. But how do they make this journey, and where do they go?
Most of the migrating raptors we're lucky enough to catch a glimpse of are birds that breed in the northeastern U.S. and/or eastern Canada. This natural wonder begins in Pennsylvania in mid-August and may continue until early December, depending on the species. Annual records show specific species prefer to migrate during precise times during this five month period, with some numbers peaking for only a couple short weeks. For example, Broad-winged hawks are one species that will migrate together in large flocks, with thousands of numbers passing through Pennsylvania in mid-September, dwindling down to few or no sightings two weeks later. When I was younger, my dad and I were lucky enough to be sitting up on Hawk Mountain on one of these amazing migration days. We watched in amazement as large flocks of Broad-wings, called 'kettles,' soared in the sky above our heads. I will never forget it and it was one of my top ten nature events! They were able to wing their way south using strong winds, updrafts and thermals.
The Appalachian Mountains stretch from Maine to Georgia, and straight through the heart of Pennsylvania. It's this mountain range, and the many smaller ranges that run parallel alongside, that these birds of prey pattern their migration routes along. Basically, when the wind blows from the northwest it hits these north-to-south ridges on a slight perpendicular angle, creating updrafts for the birds to gain altitude, as well as blowing from behind them to help push them south-both important in conserving precious energy. In addition, thermals, pockets of warm rising air, are created when the ground in certain areas (like cities) is heated by the sun. Many species of hawks, especially the Broad-wings in September, find these thermals and use them to rise in the sky before continuing on their trip south.
The Broad-wings are also one of the longest distance travelers of all the raptor species, migrating from northeastern U.S. and Canada, to the neotropics-from Mexico down to southern Brazil, where they spend their winter. When spring rolls around, they flap their way back north again-a round-trip distance of nearly 10,000 miles! That's a lot of air miles!
One of the greatest natural 'shows' on earth is once again in full flight. If you see a weather forecast predicting for strong northwest winds, get outside and take a moment to look up. You might just catch a sight of a Broad-winged Hawk, Bald Eagle or even Peregrine Falcon beginning its long journey south.