Cooper’s hawks and sharp-shinned hawks are two very similar hawk species found throughout North America. They are both in the genus Accipiter, which are woodland hawks characterized by short, rounded wings and long tails that help them maneuver deftly through dense vegetation in pursuit of small bird prey. While the two species overlap significantly in size and appearance, there are some key differences to help identify them.
Size Difference
The most reliable way to tell a Cooper’s hawk from a sharp-shinned hawk is by size. Cooper’s hawks are larger on average than sharp-shinned hawks. The length ranges are:
Species | Length |
---|---|
Cooper’s Hawk | 14-20 inches |
Sharp-shinned Hawk | 9-13 inches |
As you can see, there is some overlap in the length ranges, but Cooper’s hawks are consistently larger on average. Female Cooper’s hawks can be especially large and approach the lower size ranges of goshawks, while male sharp-shinned hawks can be quite diminutive for the species.
Wingspan is another useful size indicator. Cooper’s hawks have wingspans of 24-35 inches, while sharp-shinned hawks are smaller at 16-27 inches across. Again, some overlap exists but the larger end of the ranges can help differentiate the species.
Of course, size is most useful when you have both species side by side or have experience seeing them regularly. On its own, size can be tricky since the differences are relative. But it remains a key starting point for identification.
Head Shape
Head shape is another reliable way to distinguish sharp-shinned and Cooper’s hawks. Looking at the head on, Cooper’s hawks have a more rounded head with a broader forehead. Their eyes also appear larger and situated more towards the middle of the face.
Sharp-shinned hawks, on the other hand, have a more slender, pinched in forehead and face. Their eyes seem small and situated closer to the base of the bill, giving them a fierce “darter’s stare.” The slimmer head shape on a sharp-shin is one of the more consistent identification points in field guides.
Tail Length
Relative tail length can also be a helpful clue, though it requires seeing the full bird. Cooper’s hawks have a longer tail in proportion to their wings and body than sharp-shinned hawks. Looking at a relaxed perched bird from below, Cooper’s hawks show a tail that sticks out farther from the wingtips. Sharp-shins have a shorter tail that does not protrude much beyond the wingtips.
This difference ties into their flight styles. Longer tails aid Cooper’s hawks in their adaptation to pursuing prey in more densely vegetated habitats compared to the more open pursuits of sharp-shinned hawks. However, tail length is quite variable and only useful as a supporting not primary identification mark.
Plumage Coloration
Plumage coloration provides some clues but has limitations for differentiating the two species. Adults of both species have similar plumages consisting of slate blue-gray backs and pale underparts with rufous barring. The main plumage difference is Cooper’s hawks have a dark cap on the crown that is absent on sharp-shinned hawks.
The cap on Cooper’s can create noticeably darker head compared to the lighter gray head of sharp-shins. However, it is not always easy to discern and varies with lighting conditions. Relying solely on head color is not advised.
Immature birds of both species have brown upperparts rather than gray, and heavy brown streaking on the underparts. This can make young birds very challenging to differentiate, even more so than adults. Plumage characteristics are just not consistent enough on their own.
Habitat Preference
Habitat preferences provide another clue but with some caveats. Cooper’s hawks are birds of forest interiors. They prefer to hunt in mature forests, wooded suburban areas, and other treed habitats. Although they sometimes hunt more open environments as well.
Sharp-shinned hawks are more likely to be found in open woodland, forest edge, scrubby second growth, and open habitats. However, there is much overlap. Sharp-shins do hunt in dense woods at times while cooper’s will utilize more open areas.
During migration is when these habitat clues are weakest, since both species can be seen almost anywhere. Overall, habitat provides contextual clues but is not diagnostic by itself when the ranges overlap so broadly.
Hunting Behavior
Hunting behavior differs between Cooper’s and sharp-shinned hawks based on their habitat preference differences. Cooper’s hawks are adept at maneuvering through dense cover in high speed chases. They utilize a quick flap, flap, glide style that provides agility. Their flight style has been described as more “crow-like.”
Sharp-shinned hawks hunt more in open areas and use a flap, flap, flap style of flying with quicker wingbeats. Their flight style has been called more “songbird-like”. However these distinctions in hunting behavior can be subtle and variable.
In terms of prey, Cooper’s hawks take a higher proportion of mid-sized birds like doves and woodpeckers, while sharp-shins focus more on small songbirds. But both will opportunistically take prey based on availability, including small mammals.
Vocalizations
The calls of Cooper’s and sharp-shinned hawks differ and can provide confirmation when heard. The Cooper’s hawk makes a loud “kak kak kak” noise that carries some distance. This is often given during the breeding season. Sharp-shinned hawks make a thinner “kek kek kek” call that does not seem to carry as far.
However, visually distinguishing the two species based on vocalizations alone can be tricky. The calls are not frequent or consistent enough to rely on solely for identification in the field.
Geographic Distribution
The geographic breeding ranges of these species can provide some clues but again with limitations. In western North America, where only Cooper’s hawks occur, any small Accipiter can be safely assumed to be a Cooper’s. The opposite is true in parts of Canada and Alaska where only sharp-shinned hawks occur.
However, over most of the eastern United States these species broadly overlap. Here habitat and plumage differences are required. Checking local distribution maps when identifying an unknown accipiter can still be helpful to narrow down the possibilities.
Conclusion
In summary, there are several differences that allow skilled birders to confidently differentiate sharp-shinned and Cooper’s hawks, but it can be tricky in the field. Size is the most reliable indicator, followed by head shape and tail length. Plumage coloration, habitat preferences, hunting behavior and vocalizations provide supporting clues.
Often getting clear views and using several traits together is required for certain identification. Overall, Cooper’s hawks are larger, have a stockier build, larger rounded head, longer tail, broad forehead and vocalize with a louder “kak” call. Sharp-shinned hawks are smaller, slimmer, have a narrow pinched face, short tail, small forehead and give a thinner “kek kek” call.
With practice observing both species, the differences start to become more obvious. But some individuals will still cause head-scratching in the field. Using photos or recordings to double-check can help confirm the identification in those cases.
Being able to distinguish Cooper’s from sharp-shinned hawks allows observers to better understand the habitat distributions, migratory patterns and ecology of these fascinating woodland raptors. While identification can be tricky at first, paying attention to size, head shape, tail length and other subtle clues will yield success over time. Persistence pays off when learning to identify species that are close cousins.