Published October 13, 2010, 12:00 AM

Variations abound for this red-tailed hawk

The red-tailed hawk (Buteo jamaicensis) is about as common an airborne predator as there is.

By: Keith Corliss, West Fargo Pioneer

The red-tailed hawk (Buteo jamaicensis) is about as common an airborne predator as there is. During the breeding season, this large soaring hawk can be found in just about any habitat from mainland Alaska to the tip of Florida, even down into Central America. For this reason, it’s probably the most visually recognized bird of prey in this country. Even its voice is known to all. Virtually every movie-goer has heard its classic chill-inducing raspy scream at one time or another on a soundtrack, even when the depicted bird is not a red-tailed hawk.

During the fall season, the birds depart their more northerly haunts to find suitable wintering areas to the south, ones with less snow to hide prey. On certain days their collective flights can be quite dense, even in areas not known to be great migratory corridors such as the Red River Valley. Just last Saturday, a bird watcher from Moorhead reported seeing 50 red-tailed hawks flying south along the Red.

Also last weekend, I helped out a Clay County farmer by chisel-plowing a soy bean and wheat field north of Dilworth. It took the better part of two days to finish up. Both days, as you’ll recall, were much warmer than is usual for mid-October. I’m not sure if this contributed to the situation but for nearly the entire time the sun was up hordes of red-tailed hawks treated the freshly turned ground as a killing field.

Given the vast range this bird occupies, it should come as little surprise that there is an extreme diversity when it comes to what the birds look like; from nearly all-black birds to nearly all-white ones and every variation in between. There’s even some that lack red tails. In all, about 13 different subspecies are recognized. Within these are even more variations the experts call color morphs, which are usually classified as “dark,” “light,” or “intermediate.” The one North Dakota is sort of famous for is the “Krider’s” red-tailed hawk, a very pale bird of the northern prairie Brian Wheeler calls “very uncommon to uncommon.”

Those days in the tractor were studies in red-tailed hawk variation. Both adults and juveniles made up the whirling groups. Some would soar, some would hover, some would kite, some would dive, and some merely sat in nearby trees. At one point I counted 20 birds occupying all points of the compass. But all looked at least slightly different.

Dark-morphed birds are virtually non-existent here in the summer but are commonly encountered starting at about the Rocky Mountain foothills. There were at least two among the crowd last weekend. A very light bird which may have been a “Krider’s” hawk was also noted. But the crown jewel of the day had to be the one very dark bird with a mottled white tail, a “Harlan’s” red-tailed hawk. This subspecies nests in interior Alaska and northwest Canada. I have seen very few “Harlan’s” hawks in all my years, so this was pretty special.

Apart from the visible parade, it was a treat to witness the birds’ behavior. To my knowledge, intelligence has never really been attributed to red-tailed hawks. Yet I had to wonder. By folks who study such things, a conditioned response is considered the simplest form of learned behavior. Might these hawks have learned that a large and loud piece of machinery moving along the “prairie” produces an abundance of scattering rodents? I believe they did. Were the juveniles “learning” from the adults? Were the birds just soaring by and happened upon the scene by chance? In a slow car one might get one power pole away before a red-tailed hawk flushes, yet these birds were landing 15 feet away from a John Deere 9400 with limited wariness. I’m not sure, but I had the sense these hawks had done this before.

The only frustrating part of the weekend was the limitations. The windows were glaring and dusty and I mostly got fleeting glimpses of the hawks. But by carrying a camera the second day I got some okay shots. Still, if you encounter a plowed field northeast of Moorhead with lines that seem to swerve every now and again, I plead guilty.

Corliss is a West Fargo resident, avid birder, and ND Game and Fish volunteer instructor. He serves as a corporate pilot for Forum Communications. kcorliss@forumcomm.com.

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