Taking a rest before heading south.
What is a Broad-Winged Hawk?
Broad-winged Hawks are not an uncommon species. Broad-wings breed in the deciduous and mixed forests of eastern and central North America. They are classified as complete migrants. That means the entire population, with rare exception, migrates to wintering grounds in southern Mexico, Central and South America.
With the help of data collated from a nationwide network of hawk watches largely conducted by volunteer citizen scientists, researchers have obtained a fairly precise understanding of how climate, weather and topography combine to drive hawk migration.
Broad-winged Hawks are one of the few species of North American raptors that migrate in flocks. This makes finding the next thermal a group effort. Once a thermal is located the birds gather in a flock, sometimes numbering in the thousands.
Hawk watchers refer to a group of raptors rising on a thermal as a “kettle” because the birds resemble bubbles rising in a boiling kettle.
When the birds stream out from the top of the thermal they do so either in a line, one following the other, or in broad phalanxes that resemble squadrons of airplanes. It is quite a sight to behold.
A comprehensive look at the broad-winged hawk's migration pattern.
Broad-wings don’t like to fly over big bodies of water. Why? Because there are no thermals rising from the cool water and no ridges providing uplift.
Cape May gets high numbers of broad-wings because migrating hawks follow the coastline until they run into the Delaware Bay. Here they pause until they find a route across the bay that suits them.
This aversion to water also explains a phenomenon seen in Texas, Mexico and Central America. Remember, Broad-winged Hawks are complete migrants. That means every Broad-winged Hawk, along with other migrating raptor species, funnel down through Texas into Mexico on their way to their wintering grounds. This happens within a small time window and over a very narrow land mass.
Millions of broad-wings fly overhead in a season. It’s a spectacle widely known as the River of Raptors.
This concentration of birds necessarily creates flocks and kettles of raptors that number in the tens and even hundreds of thousands in a day.