Birds: Cooper’s / Sharp-Shinned Hawks
Tracy and I were walking the Fairmount Loop in January, 2021, when we spotted a hawk sitting on the branch of big-leaf maple tree, tearing apart a small bird in it’s talons. Standing erect as we walked by, we were no more than 10 feet from the shredding scene. Taking its time, the bird continued to pull apart the prey, while we silently passed. Tracy grabbed my arm when were were out of sight and asked what it was. I said with little conviction. “I think it was a Cooper’s Hawks … or a Sharp-Shinned Hawk. I am not sure which.” We spotted another hawk a few months later that looked identical to the one we had spotted in January, but again, I was hesitant to claim it as one or the other. Without a point of reference these two, for me, are hard to tell apart.
So which was it? Cooper or Sharp-Shinned?
Cooper’s Hawk (Accipiter cooperii)
Cooper’s Hawks are smallish “bird hawks” (slightly smaller than an adult crow) with rounded wings, a long rounded tail, and long yellow legs. This is the mid-sized accipiter nesting in Oregon and is larger than the Sharp-Shinned Hawk, but smaller than the Northern Goshawk.
The usual mode of flight consists of several rapid wing-beats alternating with brief periods of sailing. Juveniles are dark above with underparts streaked vertically, while adults tend to have a bluish cast to their gray upperparts. The long tail is barred dark and light with a narrow, whitish band at the tip.
It is an uncommon breeder in forests and woods through the state except in arid treeless areas of southeastern Oregon. It is also an uncommon transient and winter visitor statewide. The Cooper’s Hawk is also known as the big blue darter, chicken hawk, flying cross, hen hawk, quail hawk, striker, and swift hawk. 
Sharp-Shinned Hawk (Accipiter striatus)
The Sharp-Shinned Hawk is North America’s smallest and most migratory accipiter.
As a hunter of songbirds (and sometimes young chickens) it historically endured harsh reproach, and was often depicted as a blood-thirsty villain, even by some ornithologists. Across the U.S., many thousands were shot in the first half of the 20th century. But prevailing attitudes have changed, and today a glimpse of this slender, secretive hawk darting through the treetops is more likely to elicit admiration than malice.
Adult plumage, nearly identical to the slightly larger Cooper’s Hawk, consists of slate gray back and wings, breast and sides barred with rufous and white, and a black and gray banded tail. The eyes of adults are a striking crimson. Males average about 57 percent the body mass of females.
The Sharp-Shinned Hawk is an uncommon breeder throughout Oregon in forested areas from sea level to timberline. It is least common in the breeding season in southeastern Oregon, where most forests are widely disjunct and separated by arid brushland. It is an uncommon transient and winter visitor across the state in wooded areas or semi-open country. During fall migration, many birds move through the state to wintering grounds farther south. 
So which species did we see? Still not sure.
Images of small hawks and a kestrel
Who is the Cooper in the Name?
Wondering who was the Cooper as in Cooper’s Hawk, I found that the name comes from William Cooper (1798–1864). A curious character in the bird world, William Cooper was a New York naturalist and seashell scientist, best known for his work on conch shells. Cooper, like John J. Audubon, shot all of the birds he studied. Documentation stated that Cooper was the first naturalists to identify the hawk as a separate species. The name Cooper (cooperii) was added to the hawk’s scientific name by Charles L. Bonaparte in 1828, because he admired Cooper’s work and wanted to honor his friend and fellow ornithologist. “The Cooper Ornithological Society,” coincidentally, is not named for William Cooper but for his son, James Cooper, who was an avid birder and scientist. 
More About Hawks
The attitude toward Cooper’s Hawks and Sharp-Shinned cousins has changed, along with the times. Highly respected ornithologist, Arthur Cleveland Bent, in his 1937 work Life Histories of North American Birds, referred to the Cooper’s Hawk as a “feathered ferocity.” Bent shot and killed many of the Cooper’s Hawks he spotted as far back as 1874, leaving few to be permitted to escape the rifle shot.
Until the mid-twentieth century, these small hawks were hunted as vermin. Indeed the poultry farmers considered this “chicken hawk” one of their primary foes. The Migratory Bird Treaty Act of 1918  changed all that and became the Cooper’s Hawk’s, Sharp-Shinned Hawks, and American Kestrel’s protection when it was amended in 1972 to include raptors, making it illegal to kill a raptor  or take their eggs or even their feathers. During that same time period, chicken farming evolved to the current system in which the chickens are better protected in environmentally controlled facilities; even the suburban farmer with a backyard coop now focuses on other means of protection than his shotgun.
The beleaguered Cooper’s Hawk of the early twentieth century, for example, became an endangered species in many states, and use of pesticides in the period after World War II further decimated the hawk. With cessation of use of some of the more harmful pesticides, such as DDT, a slow but steady increase in the number of breeding pairs began in the 1960’s to 1970’s. Now, the population has recovered, and the species thrives once more.
Today, instead of regarding these hawks as a “blood-thirsty villain,” it is more fashionable to focus on the Cooper’s Hawk’s admirable traits: his agility and speed, his hunting prowess, his feisty attitude. Now, we are more tolerant of his appetite for avian prey.
Cooper’s Hawks are monogamous, but if something happens to one, the lone hawk will seek another mate. The female is dominant, and the male hawk defers to his mate, keeping his distance from her whenever possible. During the mating season, he will usually gift her with prey and wait for an invitation before approaching her. When she is ready, she will vocalize and get into the right position for him; after mating, the male side-steps or flies quickly away. Since the average male is only around 60% of the size of his mate, and keeping in mind that her favorite prey is a bird about his size, it seems wise for him to treat her with respect.
There are a lot of terrific articles about the life and times in Cooper Hawk land that I recommend for anyone who wants to dig into the riparian zone with these guys. 
 Birds of prey, also known as raptors, include many different species of birds that primarily hunt and feed on other vertebrates that are large relative to the size of the hunter. Additionally, they have several other distinctive physical characteristics: 1) keen eyesight for detecting food at a distance or during flight, 2) strong feet equipped with talons for grasping or killing prey, and 3) powerful, curved beaks or bills for tearing flesh. The term raptor is derived from the Latin word rapio, meaning to seize or take by force. In addition to hunting live prey, many of these birds, such as fish eagles, vultures, and condors, also eat carrion (flesh of dead animals). For more information see: https://en.wikipedia.org/wiki/Bird_of_prey
 https://www.thespruce.com/coopers-hawk-387242 and lots more