Each fall, volunteer watchers put in countless hours sitting on scenic vistas that provide excellent views of the ridges and valleys and a clear line of sight for oncoming raptors in order to count the birds migrating south. Starting in early September, multiple locations in our region are available to observe avian behavior at its finest.
Most raptor migration occurs along “leading lines” — geographic features such as mountain ranges, coastlines or barriers like oceans — to guide their journey south.
Because raptors are soaring migrants, they need uplift or thermals to travel great distances to conserve energy. Uplift is a term that refers to wind hitting a mountain range perpendicularly, causing the wind to deflect up and over. Thermal soaring takes place when raptors circle in warm pockets of rising air caused by the increase of the Earth’s ground temperature by the sun. Once a raptor soars high enough, it will exit the thermal and glide until it reaches another thermal farther down the ridge. Central Pennsylvania’s terrain and geographic location make this area well-known for viewing migrant raptors.
Bird migration does not happen all at once. Looking at where each raptor spends its time overwintering can help identify the timing of its flight over central Pennsylvania. The broad-winged hawk travels from as far north as Canada’s boreal forest to the deep tropical forests of Central and South America, covering several thousand miles in its travels, the longest trip of the eastern migratory raptors.
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Their expected migration period begins in late August for those getting a head start, but the peak is in mid-September, with central Pennsylvania high counts reaching to 1,200 individuals in a day. From here, they continue south and are bottlenecked through the tip of southern Texas and into Mexico, where hawk counters can tally 1 million or more in a day. It is a spectacular sight to witness.
As the fall migration slowly trickles away, golden eagles are the last migrants observed on the watches here in November. Golden eagles begin their journey at the rocky ledges of northeast Canada, Nova Scotia, Gaspe Peninsula and similar areas. But unlike broad-winged hawks, they travel only as far south as the southern tip of the Appalachian Ridges in West Virginia, Alabama, Mississippi and Arkansas. At times, individuals are even seen overwintering here in central Pennsylvania.
If you are looking for an interesting day trip, there are three well-known fall hawkwatch sites you can visit. Two of the three are ideal for the fall migration: Jacks Mountain to the south of Belleville/Big Valley and Stone Mountain bordering the north side of Big Valley. The third, Jo Hays Vista, about 7 miles southwest of State College, is not as popular for fall hawkwatching but is well-known for robust spring migration, including the large numbers of golden eagles that use this route to go north.
As this season progresses, keep your eyes to the sky, and you may see migratory raptors in large groups or as individuals traversing the sky and moving to another landscape for the winter.
OLLI at Penn State — open to adults who love to learn — will be offering more than 120 courses this fall, including “Fall Raptor Migration at Jacks Mountain,” led by Jennifer Steigerwalt. To receive a free fall semester catalog, call OLLI at Penn State at 867-4278 or visit olli.psu.edu.
Jon Kauffman is the assistant raptor center director at Shaver’s Creek Environmental Center.
The 3 phases of fall raptor migration
Kauffman recommends looking for raptor species this fall in three phases:
Mid-September: Broad-winged hawks, bald eagles and American kestrels
Early to mid-October: Sharp-shinned hawk, Cooper’s hawk, Merlins and peregrine falcons
Mid-October to mid-November: Red-tailed hawks, red-shouldered hawks and golden eagles
Raptor counters usually maintain each watch from 9 a.m.-5 p.m., depending on weather. Anytime is a good time to watch, but 10 a.m.-2 p.m. is typically the most productive time span to see birds. For more information, visit www.hawkcount.org and the State College Bird Club’s website, www.scbirdcl.org.