As I have said many times, my passion for the outdoors began with an unbridled fascination with reptiles. Growing up as a budding naturalist I wasn’t the most avid birding enthusiast, but even at a young age I found myself a little in love with the group of birds known as raptors. And one species of raptor that I certainly saw in my youth was a common summer resident, the Swainson’s hawk.
The Swainson’s Hawk (Buteo swainsoni) is a large bird of prey found throughout the plains of North America, from southern Canada to Texas. Throughout its North American range, it is a migratory species. This means that he resides in North America (including west ¾ Texas) during the warmer summer months and lives in warmer regions during the winter. However, unlike some migratory birds that spend the winter months in central Mexico before returning north for the summer, this species of raptor makes winter home in Argentina. This means that individual birds, depending on where they inhabit during the summer, can travel over 15,000 miles per year!
This particular species of falcon prefers to occupy open areas such as meadows, meadows, plains, and rangelands. All of these areas are generally devoid of dense tree canopy, allowing this visually keen species to watch the area for its next potential meal. It is quick to use man-made objects such as fence posts and electric poles as perching areas, and I have seen several specimens in the Trans-Pecos exploiting sotols and agaves for the same purpose.
Swainson’s hawks come in three distinct color forms, which sometimes makes identification a bit problematic. Some individuals are dark while others have dark upperparts and slightly lighter underparts. Both of these morphs have a distinctive white throat that can be used to distinguish it from other species. However, the most common form of color in Texas is a bit more colorful. As in the 2 darker forms, the light form has dark upperparts and a white throat, but the belly is usually dull white which is sometimes slightly mottled around the periphery. There is a distinctive broad band of brown color across the chest. The tail feathers are colored similarly to the upperparts and often have narrow, pale gray bands.
The head is predominantly brown with clear lines and the thick, curved bill is black with a fleshy yellow area on top of the upper bill known as cere. The eyes are large and quite dark. The yellowish scaly legs and feet are feathered almost to the long, powerful talons.
Swainson’s hawks are large, in fact they are the 2nd largest of the 8 species of the genus Buteo that occur in Texas, rivaled in size only by the slightly larger red-tailed hawk. An adult specimen can reach a body height of 23 inches with a wingspan of just under five feet. Large adults can weigh up to 2 ¾ pounds.
Reproduction takes place in late spring and this species is monogamous for the season. The 2-4 greenish-white eggs are laid about a month later in a nest built by both parents and made of sticks and twigs. These eggs are large, nearly 2 1/3 inches in length, and usually have light brown spots. The incubation time varies, but it usually takes about a month. The young stay in the nest for an additional month and are fed by both parents.
This species of falcon is a food generalist, consuming large amounts of insects such as grasshoppers. However, it does not limit its prey to such small creatures, as it is also known to feed on mice, rats, rabbits, lizards, frogs, toads and ground squirrels. I have seen many Swainson’s hawks stalk prairie dogs at the entrance to their burrows. The keen eyesight of hawks thanks to the large eyes is able to see prey several hundred feet above ground level.
Studies on this large bird of prey suggest populations are holding up, at least in North America. There is some concern for this species where it uses its winter home due to the continued use of pesticides.
Michael Price is the owner of Wild About Texas, an educational company specializing in poisonous animal safety training, environmental counseling, and eco-tourism. Contact him at [email protected]