Trends come and go. This year one of the big puzzles has been the dramatically higher numbers of adult and older juvenile Broad-winged Hawks (Buteo platypterus). Last year the numbers were up also, just not as dramatically. The Texas Gulf Coast usually sees these small hawks in the spring and fall as they migrate from their wintering grounds in Mexico down to South America to nesting grounds in most of the eastern United States. The greater Houston area is on the far western edge of traditional nesting grounds, so nesting pairs and their chicks isn’t unheard of, but is unusual. What is strange is that so many adult and older juvenile Broad-winged Hawks are finding their way to the Wildlife Center.
Broad-winged Hawk are the size of a large crow and can be easily confused with older juvenile Red-shouldered Hawk at a glance. There are two color morphs; light which is the traditional hawk coloration and dark which is a deep sooty brown. The dark morph is extremely rare. The head and chest/belly bands are cinnamon brown. The wings are a solid darker brown with cream underneath. The tail is short and barred. In flight, the wings are broad and relatively short. The silhouette of the wing is uniquely pointed.
They don’t seem to have a preference for the type of forest (deciduous vs. conifer) as long as it provides sufficient cover. They are rarely seen when nesting or wintering since they don’t tend to hunt open ground along the perimeter of forested areas. Instead, they ambush hunt from an advantageous perch. They also rarely hunt on the wing, so there are fewer opportunities to see this bird in the wild, EXCEPT during migration.
During migration, groups of several individuals to thousands make the trek together. If the winds are favorable for several days, tens of thousands can be sighted. Except in the Caribbean where the Broad-winged Hawk don’t migrate, there is virtually no overlap of nesting and wintering grounds. Kettles returning to their wintering grounds often form in the northeastern United States and merge into larger groups as they sweep along the Texas Gulf Coast and into Mexico. These flyways are well established and experienced birders know when and where sightings are likely to occur.
A small study followed Broad-winged Hawks by way of satellite transmitters. The average migration was almost 4,400 miles. The daily average was almost 70 miles. Once settled into their wintering grounds, the hawks were homebodies and stayed in a one square mile territory.
Only time will tell if the nesting area for the Broad-winged Hawk will shift well into the Texas Gulf Coast. It may simply be a temporary shift in response to environmental pressures. Another odd trend is that some of these nesting pairs are hatching babies too late in the year to join their parents when they migrate this fall. So will the parents and/or chicks over-winter in Houston? The upper Gulf Coast is warm enough for over-wintering so it is a possibility. 2011 could prove to be a very interesting year.