Explore, Enjoy, and Protect the Planet

On The Trail — September 2007

Enjoy the Spectacle of Autumn Hawk Migration at the Stone Mountain Hawk Watch

by Dr. Stan Kotala

Summer’s waning days yield to the coolness of autumn, and overhead a great migration is occurring, one that can be observed easily over the next three months. The exodus of birds of prey from their northern breeding grounds is just now beginning, and throughout the Keystone State tens-of-thousands of people are flocking to ridgetop observation areas to watch the spectacle.

The long linear ridges of central Pennsylvania serve as important flyways for hawks, falcons, and eagles, collectively known as raptors. These ridges, oriented from northeast to southwest, enable birds of prey to take advantage of air currents known as thermals as well as of winds deflected off the ridges to cover long distances by gliding, thus expending a minimal amount of energy. Our linear ridges make Pennsylvania an internationally acclaimed hotspot for raptor watching. Depending on volunteer hawk watch hours, several thousand to 20,000+ raptors may be observed along a single ridge during a single migration season.

Raptors soar and glide more often earlier in the season when thermal production is high. Thermals are pockets of warm air that form when the sun strikes the earth, causing a warmed bubble of air to rise. Migrating raptors find these thermals and soar upward on the rising air. After reaching the top, the birds glide south until they catch another thermal. By late October through December thermal production sharply decreases, and migrating raptors employ a combination of gliding and flapping, taking advantage of wind deflected off the ridges. Raptors will often fly directly above the ridge, coming closer to the ridge as the wind speed increases. In addition, they are often observed nearer to the ridge in the morning and late afternoon.

A number of Pennsylvania’s ridges have been designated as Important Bird Ares (IBAs) by the Pennsylvania Biological Survey due to the role they play in raptor migrations. IBAs with established hawk watch sites include the Kittatinny Ridge at Waggoner’s Gap (Perry/Cumberland Counties), Hawk Mountain Sanctuary (Berks County), Second Mountain (Fort Indiantown Gap, Dauphin County), Tuscarora Mountain at “The Pulpit” (Franklin County), and the ridge top at State Game Lands (SGL) 88 (on the Perry/Juniata County border), Stone Mountain (Rothrock State Forest, Mifflin/Huntingdon Counies), Tussey Mountain (on the powercut west of Route 26 on the Huntingdon/Centre County line), Bald Eagle Ridge (Centre, Huntingdon, and Blair Counties), and Audubon Pennsylvania’s newest IBA, The Allegheny Front (Allegheny Front hawk watch, Bedford County). One site with very easy access that isn’t an IBA but still bears mention is the Jack’s Mountain Hawk Watch on Jack’s Mountain (Mifflin County) where state route 4007 (Wills Road) crosses the ridge.

We’ll focus on our most productive local hawk watch, the Stone Mountain Hawkwatch in Rothrock State Forest. Stone Mountain Hawkwatch (elevation 2,100) was established in 1991 and is on the Huntingdon/Mifflin County border, 20 miles south of State College. From September 1 through mid-November, the site is manned on weekends and sporadically during the week by hawk counters from the State College Bird Club. The highest numbers of hawks are observed on days with westerly or northwesterly winds. The hawkwatch platform is located on a trail 1/3 mile north of the crossing of Stone Mountain ridge by the Allensville Road (gravel) — a very rocky 10-minute walk for the nimble, but difficult for some folks.

The ridgetop of Stone Mountain consists of large expanses of forest interspersed with clearings formed by talus slopes and rocky outcroppings. The dominant trees are chestnut oaks, most of which are relatively small, but also old because the harsh conditions on the ridgetop aren’t conducive to rapid growth. The trail is marked clearly by orange blazes. In any case, the ridgetop is extremely narrow, so, if you follow the spine of the ridge northward from the parking area, then you’re bound to find the hawkwatch platform. On your way, watch your step during the warmer months, because the ridgetop has a healthy population of timber rattlesnakes. Seeing one is a rare treat!

The platform was constructed by volunteers from the State College Bird Club and Juniata Valley Audubon more than a decade ago. Built of wood and painted gray, it blends in well with its surroundings. From the hawkwatch platform you enjoy a commanding view of Stone Valley’s largely forested landscape to the west and Big Valley’s (Kishacoquillas Valley’s) farmland to the east. Beyond the valleys Tussey Mountain to the west and Jack’s Mountain to the east. Sadly, the hawkwatch on Jack’s Mountain is threatened by a 50-turbine industrial windfarm that is proposed for the top of that ridge.

Once you arrive at the Stone Mountain Hawkwatch site make yourself comfortable and keep your binoculars handy. There’s usually an experienced hawkwatcher or two or three or ten present to help you with identification. Speaking of binoculars, most hawkwatchers prefer 10x models, but any binocular will do. Some of the raptors will fly low to investigate, and sometimes attack, a plastic owl that’s mounted to the viewing platform. Others will be so high up that they’ll look like specks in the sky. Keep in mind that a visit to the Stone Mountain Hawkwatch is not for those with short attention spans and a restless nature. Although there may be days when the hawks come soaring by like leaves blowing downwind in a storm, such days are the exception. Patience is necessary, and it will be rewarded. Just bring enough food and drink to last a few hours and you’ll see your share of migrating raptors.

Early in the season, in September, is when the thermals are formed and it’s then that you’ll see the greatest numbers of broad-winged hawks, which often soar in large groups called kettles. Broad-winged hawks fly under almost all non-rain conditions when they are ready to go. For other raptors, conditions are far superior on days following cold front passages with northwesterly or westerly winds. Through October, you'll also have a good chance of seeing bald eagles, ospreys, Cooper’s hawks, sharp-shinned hawks, and American kestrels. November brings golden eagles, red-shouldered hawks, red-tailed hawks, and northern harriers. Falcons aren’t too common at the Stone Mountain hawkwatch, but you may get lucky in October and see a peregrine or a merlin.

Although the trip to the Stone Mountain Hawkwatch is not a long hike, it offers many hours of pleasurable viewing of the spectacle of raptor migration, camaraderie with other hawk watchers, and fantastic views of a glorious autumn landscape.

Directions to the Stone Mountain Hawkwatch: Take Rt 26 south from State College to Pine Grove Mills. In Pine Grove Mills Rt 26 makes a left turn at a flashing traffic light and goes up over Tussey Mountain. At this point you pass into Huntingdon County. Continue south on Rt 26 to the town of McAlevy’s Fort. As you enter McAlevy’s Fort, you pass a fire station on the right, go over a bridge, and come to a STOP sign.

At the stop sign, turn left onto Rt 305 (also now called Greenwood Road). Proceed 0.7 mile, passing a large brick church on the left, and then immediately turn right (leaving 305) onto paved Barr Road. Continue on this winding road for 0.6 mile, then turn left onto (paved) Davis Road. Follow Davis Road about 1.2 miles down to East Branch Road (there are no possible prior turns off Davis Road).

Turn right onto East Branch Road. Follow it for 1.6 miles to a left turn onto Allensville Road (dirt but drivable except in snow/ice conditions). Follow Allensville Road three miles to the very top of Stone Mountain. At the top, park on the left side of Allensville Road. Follow the obvious trail north into the woods (to the left of the road). After 50 yards you will cross a small, semi-difficult rock field. Then pick up the orange-blazed Standing Stone Trail (formerly known as the Link Trail) and follow 5 to 10 minutes more along the ridge out to the platform. You can’t miss it if you stay on the trail on the ridgetop.

Dr. Stan Kotala is the Wildlife Chair for the Moshannon Group of the Sierra Club as well as president of Juniata Valley Audubon. He’ll lead a Stone Mountain Hawkwatch hike on Saturday, September 22, from 3 to 5 p.m. Meet at the Bank parking lot on Route 26 in McAlevy’s Fort, Huntingdon County at 2:30 p.m.