Sharp-shinned and Cooper’s hawks are two similar accipiter species found throughout North America. While they can be challenging to distinguish visually, especially among females and young birds, their vocalizations differ noticeably and can be a useful aid for identification.
Sharp-shinned Hawk Call
The Sharp-shinned Hawk has a high-pitched, rasping “kik-kik-kik” call. This call is often given in rapid series of up to 30 notes at intervals of 1-3 seconds when the bird is alarmed or during the breeding season.
Some key features of the Sharp-shinned Hawk call include:
- High frequency around 4-8 KHz
- Raspy, tearing quality
- Notes all similar in pitch and volume
- Call series is rapid with notes given at regular intervals
To human ears, the call is reminiscent of two wooden blocks or sticks being rapidly rubbed together. It does not have clear tonal quality like some songbird vocalizations. Below is a spectrogram showing the raspy, broadband nature of the Sharp-shinned call:
Here is an audio clip of the Sharp-shinned Hawk’s typical call series:
Cooper’s Hawk Call
The Cooper’s Hawk call is a louder, more forceful “kak kak kak”. The notes are louder and lower pitched than the Sharp-shinned.
Some key features of the Cooper’s Hawk call:
- Lower frequency around 3-6 KHz
- Louder volume and more forceful delivery than Sharp-shinned
- Individual notes are sometimes doubled or tripled
- Call series accelerates towards the end
While still raspy, the Cooper’s Hawk call is cleaner and more pronounced than the high, tearing quality of the Sharp-shinned. Below is a spectrogram of a Cooper’s Hawk call showing the deeper, more defined notes:
Here is an audio clip comparing the Cooper’s Hawk call to the smaller Sharp-shinned:
Differences in Call Behavior
In addition to the pitch and tone differences, Cooper’s and Sharp-shinned Hawks differ in their typical calling behavior:
Cooper’s Hawk | Sharp-shinned Hawk | |
---|---|---|
Context | Calls more often in aggressive situations | Calls more often when alarmed |
Length of call series | Shorter, usually about 6-20 notes | Longer, up to 30 notes |
Timing | Notes accelerate towards end | Regular timing throughout |
Cooper’s Hawks are more likely to call during aggressive encounters, such as food defense or territorial disputes. Sharp-shinned calls are more frequently heard from birds that are alarmed or caught off guard.
Differences in Pitch
The smaller Sharp-shinned Hawk has a higher-pitched call that is adapted for short-range communication in dense habitats like forests. The larger Cooper’s Hawk uses a deeper, louder call that carries further in open areas.
In birds, call pitch is negatively related to body size – larger species vocalize at lower frequencies. Several anatomical adaptations allow larger hawks to produce lower-pitched vocalizations:
- Longer, thicker trachea which resonates at lower frequencies
- More developed chest muscles to power the voice
- Larger syrinx (vocal organ) with thicker membranes
The smaller Sharp-shinned has a more restricted higher-pitched call, but it is well-suited for communication through dense foliage in forest habitats. The larger Cooper’s Hawk has a deeper, louder call adapted for more open country.
Useful Identification Tip
Remembering the differences in pitch and tone between these two accipiter calls can be a helpful cue for identification:
- Higher, weaker, more tearing Sharp-shinned call
- Lower, louder, more forceful Cooper’s call
Being familiar with the characteristic differences allows birders to identify an unseen calling accipiter in habitats where both species occur. It’s one more useful tool for distinguishing these often tricky-to-ID birds.
Conclusion
In summary, the calls of Sharp-shinned and Cooper’s Hawks differ in several distinct ways:
- The Sharp-shinned has a higher-pitched “kik” call at around 4-8 KHz
- The Cooper’s Hawk has a lower-pitched “kak” call at 3-6 KHz
- Sharp-shinneds call in longer series when alarmed
- Cooper’s call more often in aggressive encounters
- Cooper’s calls accelerate, while Sharp-shinned calls are evenly timed
Remembering these differences can be helpful for identifying an unseen calling bird. The higher, faster call indicates a Sharp-shinned, while the lower, shorter, accelerating call points to a Cooper’s Hawk.
Being able to distinguish these similar accipiters by call takes practice, but with experience birders can use their vocalizations as a reliable identification feature.