Last month my son sent me a video of about 20 or more hawks that were circling above his house in Kearney. A group of hawks are called a “kettle” and this “kettle” was made up of Swainson’s Hawks. These are fairly large hawks, about the size of a red-tailed hawk which most people are familiar with.

Swainson’s Hawks nest in Nebraska and then migrate to Argentina and back on a 12,000-mile round trip! Other hawks like the red-tailed hawk only fly about 3,000 miles. During the nesting season these hawks eat the same things as red-tails do, i.e. rats, mice, and snakes; however, once breeding is completed, they mainly feed on insects…grasshoppers are a favorite.

A diet of insects caused a problem for the birds. In Argentina the pesticide monocrotophos was used to kill grasshoppers, the preferred food of the Swainson’s Hawks. The pesticide not only kills grasshoppers; it is extremely toxic to birds! A biologist had outfitted a few Swainson’s Hawks with radio transmitters, and he was tracking them from the U.S. to Argentina to find out where they overwintered. He found them, lying dead under a roost tree. He looked around and in all, he counted over 20,000 dead Swainson’s Hawks.

They still use monocrotophos in Argentina, but an educational program and more controls over the use of the deadly pesticide have resulted in far fewer birds dying. Also, the conversion of extensive prairies to soybeans in Argentina has reduced the need for the pesticide.

To me, three things stand out about Swainson’s Hawks. First, they are a large hawk that eats grasshoppers! Quite a few smaller hawks eat grasshoppers, but a hawk this big feasting on them seems strange.

Second in the “stand out” list is the migration. Kettles of Swainson’s Hawks can number in the tens of thousands, and they follow the same migration path year after year. Because of this there are locations like Hazel Bazemore Park in Corpus Christi, Texas, where people will also gather in large numbers to watch the kettles of hawks fly on by on their way south. The “river of raptors” can take hours if the kettle is large.

One observation was it took two hours for approximately 30,000 Swainson’s Hawks to fly over. Also, as noted above, they have one of the longest migrations of any hawks.

Lastly, is the name itself. Naturalist and illustrator William Swainson originally misidentified the bird. Swainson named a number of birds and plants; however, he didn’t name the hawk after himself. He painted the bird from a stuffed specimen in a museum in England where he worked. He misidentified the bird as a common buzzard, which is found throughout Europe. Instead, it turned out that the hawk he painted had been killed in Canada.

Four years later French biologist Charles Lucien Bonaparte studied a painting of a hawk done by John J. Audubon and noticed the similarities to the bird that Swainson had painted. It was then he realized that the bird both artists painted was an unnamed species. So, despite the fact that Swainson never set foot on North America or in Argentina, and that he originally misidentified the bird, Bonaparte named the species Buteo Swainsoni…the Swainson’s Hawk in his honor.