Mid-September is the peak of broad-winged hawk migration in Pennsylvania as these woodland raptors head for the forests of Central and South America.

Broad-winged hawks (Buteo platypterus) breed in North American forests but spend only four months of the year up here.  In late August they start to move south, reaching the forests in Central and South America by early November. 

What’s unusual about broad-wings is that they travel in flocks — most raptors don’t — and they watch each other for flight cues.  If one finds a thermal with good lift, others join him and rise on it as well.  Soon they form a “kettle” of hawks stirring round and round in the rising air.  As each one reaches sufficient altitude it sets its wings and glides south to find the next thermal.

If the weather’s good this weekend, hundreds if not thousands of broad-wings will kettle up and stream out over hawk watches in the Mid-Atlantic.  Here’s what it looks like on a good day, recorded at Ashland Hawk Watch in Hockessin, Delaware on September 15, 2013.

Make plans to visit a hawk watch soon. Here’s how to find one near you: Hawk Watch Information