The Cooper\u2019s hawk, left, and sharp-shinned hawk look very similar but, it turns out, are not as closely related as once thought. Cooper\u2019s hawk photo by M. Leonard Photography; sharp-shinned photo by mirceax.<\/p>\n
I remember exactly where I was when I read the news.<\/p>\n
I was sitting in the waiting room at the vet’s office, having just played a game of keep away with my dog Kit. (Keeping her away from the treats in the Science Diet display, that is.) After a vet tech came and got her for her nail trim I said hi to a couple other dogs, then pulled out my phone. And that’s when I saw it. A blurb from the Utah-based advocacy group HawkWatch International:<\/p>\n
“For those of you not in the know, the Cooper’s Hawk and American Goshawk have left the Accipiter genus and are now Asturs. It turns out the incredibly hard-to-identify Sharp-shinned and Cooper’s Hawk aren’t as closely related as previously thought!”<\/p>\n
Okay, so maybe this little bulletin not as earth-shaking as other recent headlines. But to a mediocre birder like me, who has only a rudimentary grasp of taxonomy-the practice of classifying organisims– this announcement might just as well have read, “The sky isn’t blue and grass isn’t green!”<\/p>\n
For most of my naturalist career I’ve struggled to distinguish between Cooper’s and sharpies, species so similar I figured they had to be connected. This perception dates at least as far back as 1999, the year I began volunteering at the nature center at Tekakwitha Woods in St. Charles. A new taxidermy mount had arrived, and no one was quite sure whether it was a female sharp-shinned hawk, Accipiter striatus, or a male Cooper’s, which at the time had the scientific name Accipiter cooperii.<\/p>\n
I knew Cooper’s in general were the larger of the two but also learned there is considerable overlap between the two species. I recall another volunteer dubbing the bird a Coop-shin which was-again, as a mediocre birder-close enough for me.<\/p>\n
So many things about these birds are, to my uneducated eye, nearly identical. They both have lovely reddish-orange bars across the breast and are bluish-gray across the back. Their tails have thick, dark bands, and their eyes are red. And they both specialize in feeding on other birds.<\/p>\n
But they also have their differences. For one, in our area of Kane County, Cooper’s simply are more common. They’ve adapted well to a suburban lifestyle and might just as likely be found nesting in a Norway maple on a parkway as in an oak tree in a nature preserve.<\/p>\n
Sharpies, meanwhile, require dense forests for breeding, and that’s an ecosystem we don’t we really have. When we do see sharpies, it’s usually during migration or in winter.<\/p>\n
Then there are the physical traits. Cooper’s, as noted above, are larger, with the size of the female often being compared to that of a crow. Female sharpies are smaller, comparable in size to-I kid you not-a male Cooper’s, according to Cornell’s All About Birds website.<\/p>\n
In the field though size can be difficult to gauge, so other features like head shape, markings and legs come into play. Cooper’s heads are flatter, and have a distinctive “cap” of dark feathers on top; sharpies’ heads are rounder and have a “hood” of darker feathers that extends to the nape. Coops have thicker legs that appear shorter in relation to the body; sharpies’ legs often are described as pencil like, and appear longer.<\/p>\n
But for those of us who aren’t great with binoculars or whose eyes don’t pick up on subtle details, Cooper’s and sharp-shins look practically identical. How is it that these beautiful birds are not kissing cousins??<\/p>\n
To answer that question, let’s turn that old adage-the one that goes something like, “The only constant is change.” It’s true in life, and in taxonomy.<\/p>\n
The more information that research reveals about the plants and animals around us, particularly their genetic makeup, the more informed decisions taxonomists can make about the organisms’ classification.<\/p>\n
In the case of the Coops and sharpies, it’s been known for a while that their genus, Accipter, is polyphyletic–not an everyday word, for sure! It’s derived from the Greek word polyphylos, which means of many tribes, and is applied when a group of organisms is descended from more than one common ancestor. To taxonomists, that sort of categorizing is, shall we say, no bueno.<\/p>\n
Other notable changes in the eBird 2024 Taxonomy Update include splitting the barn owl into three separate species, the herring gull into four and the house wren into seven; meanwhile, the common, hoary and lesser redpolls have been combined into one species, Acanthis flammea. All told, this year’s eBird Taxonomy Update includes three newly-described species, 141 species gained through splits and 16 species taken away by lumping species together. The new number of bird species worldwide is…drumroll…11,145!<\/p>\n
One last note about names: Another group, the American Ornithological Society, last year announced a separate project wherein birds whose common names include the name of a person will be changed to names that, ah, do not. They’re currently working on a group of between 70 and 80 birds native to North America that includes, you guessed it…<\/p>\n
The Cooper’s hawk.<\/p>\n