BY SCOTT RANDO
With September here, with some cooler mornings, a few species of birds have started to migrate south. Smaller birds, like the yellow warbler, were already on their way in late August, and some might have seen nightjars catching flying insects over lakes and rivers as they made their way also to the south.
Raptors – hawks, hawks, eagles, etc. – are easier to notice, as they are larger birds. They also tend to fly near ridges along the Appalachian Range that runs up and down the eastern part of the country.
When the wind blows from the northwest, raptors take advantage of both the tailwinds and the lift generated by the air moving up the slope on the windward side of the ridges. These conditions allow raptors to conserve energy when flying south.
The Broad-winged Hawk is one of the first raptor species to be seen at favorite hawk-watching sites. These members of the genus Buteo can sometimes be confused with red-tailed hawks.
Broad-winged hawks have a barred tail (black on white) and a black fringe is frequently seen around the wings. These falcons cross our region in a short time. The best time to see large numbers of falcons is around mid-September, when several hundred can be spotted in a single day.
Using satellite tracking of telemetered birds, scientists have determined that the average broad-winged hawk migrates 4,370 miles northward from South America.
There are other species that migrate in September. Osprey migration peaks during this time, with 10 or more birds seen per day when winds are favourable. Merlins and kestrels, small raptors of the falcon family, can also be seen during this period. There are sometimes interactions between species; this often leads to impromptu air shows.
These raptor species are spotted early when the weather is still mild; many migratory monarch butterflies pass through this period. If you don’t like the cold, September and early October are good times for hawk watching. Other species – bald and golden eagles, for example – pass through in October and November.
For the timing of migrations of various raptor species, see hawkcount.org/.