The tail feathers of a sharp-shinned hawk are a key identifying feature of this small but fierce accipiter. Like all birds, the tail feathers play an important role in flight control and maneuverability.
Anatomy of a Sharp-Shinned Hawk’s Tail
A sharp-shinned hawk has 12 tail feathers known as rectrices. These 12 feathers are arranged into a fan shape at the rear of the bird. The rectrices are numbered in pairs starting from the center. So the sharp-shinned hawk has 6 pairs of rectrices labeled R1, R2, R3, R4, R5, and R6.
Here are some key features of a sharp-shinned hawk’s rectrices:
- R1 – The central pair of rectrices. These are the smallest and help stabilize the tail.
- R2 – The second pair of rectrices moving outward. Slightly longer than R1.
- R3 – The third pair of rectrices. These are noticeably longer than R1 and R2.
- R4 – The fourth pair of rectrices. Similar in length to R3.
- R5 – The fifth pair of rectrices. The second longest pair after R6.
- R6 – The outermost pair of rectrices. The longest pair, critical for steering and braking.
This graduated length of the rectrices gives the sharp-shinned hawk’s tail a distinctive long, rounded shape. The tail is medium-length for a hawk, making up about 40% of the bird’s total length.
Color Pattern
Sharp-shinned hawks display sexual dimorphism – meaning males and females have differences in plumage coloration and patterning:
Male Sharp-Shinned Hawk
Males have slate-gray upperparts and rectrices with white barring. The barring pattern runs horizontally across the feathers:
- About 4-6 white bars on each feather
- Bars are thin and evenly spaced
- Gray background color between bars is darker on outer rectrices
This cleanly patterned tail is a useful identifier for determining males in the field.
Female Sharp-Shinned Hawk
Females have browner upperparts and rectrices with buff-brown barring:
- 3-4 thicker buff-brown bars on each feather
- Barring can be unevenly spaced
- Background color is brownish-gray
The female’s tail often appears more mottled than the male’s.
Identifying a Sharp-Shinned Hawk by the Tail
When viewed from below, a flying sharp-shinned hawk shows a long, rounded tail with distinctly squared corners:
| Sharp-Shinned Hawk Tail Shape | Description |
|---|---|
| Long | Rectrices increase gradually in length from R1 to R6 |
| Rounded | Longest rectrices (R6) do not extend far beyond the tail edges, giving the tail a rounded contour |
| Squared corners | Outer rectrices (R5 & R6) have straight edges, creating distinct corners where they meet |
This helps distinguish sharp-shinned hawks from the longer-tailed Cooper’s hawk and more rounded-tailed broad-winged hawk.
In addition, the male’s thin, evenly spaced barring is unique among North American accipiters. Female tail patterns may resemble a male Cooper’s hawk, so other features are needed for confirmation.
Function of Tail Feathers
A sharp-shinned hawk’s tail feathers serve important functions in flight:
- Steering – The hawk uses its tail as a rudder to steer and maneuver through dense habitats.
- Braking – Fanning the tail rectrices outward creates drag, allowing for rapid braking.
- Stability – Tail acts as a counterbalance to head and wings, stabilizing pitch and roll.
- Predator evasion – Hawk can twist and turn abruptly by adjusting tail, evading predators and mobbing birds.
The long tail feathers also enable sharp-shinned hawks to perform their acrobatic hunting style. They give the agile raptor tight control of speed and direction as they chase down smaller birds on the wing.
Molting Tail Feathers
Like all birds, sharp-shinned hawks molt and replace their feathers periodically. However, accipiters have a unique molt strategy for their tail feathers called asynchronous or ” staffelmauser” molt:
- Each rectrix is replaced individually over an extended period, rather than all at once.
- This ensures the hawk always has sufficient functional tail feathers for stability and steering.
Sharp-shinned hawks molt tail feathers once per year after breeding season between June and October. The order of molt is centered outward – R1 molts first followed by R6 last. Juveniles may replace rectrices again their first winter.
Newly molted tail feathers initially have a bluer sheen and crisper patterning. Over time feather colors fade and become more weathered.
Sexing a Sharp-Shinned Hawk by Tail
A sharp-shinned hawk’s tail offers useful clues to determine whether a hawk is male or female:
| Male | Female | |
|---|---|---|
| Barring color | White | Buff-brown |
| Barring thickness | Thin and evenly spaced | Thicker and unevenly spaced |
| Background color | Slate-gray | Brownish-gray |
The tail pattern differences reflect distinct breeding strategies for males and females:
- Thin white bars help camouflage sitting males in dappled light, protecting nests.
- Thicker bars on females provide better camouflage while hunting in forests.
Variation in Individuals
While the above patterns are typical, there can be some variation between individual sharp-shinned hawks:
- Number of tail bars – Usually 4-6 but ranges from 3-8 bars
- Female barring – Sometimes thinner approaching male pattern
- Male background color – Can be darker slate-gray in the Pacific Northwest
Juveniles closely resemble adult females but often show messy, indistinct barring. Their tail feathers are also shorter and more rounded.
Aberrant color variants like leucistic sharp-shins may lack normal pigment patterns.
Moult and Feather Wear
The condition of the tail feathers can also alter appearance:
- Freshly molted feathers have vivid colors and distinct markings
- Over time, sunlight bleaches feathers and makes colors fade
- Worn, frayed feathers lose their crisp pattern
- During active molt, new and old generations of feathers can be mixed
These natural processes can make tail patterns appear different across individual hawks or times of year.
Use of Tail in Identification
When identifying a sharp-shinned hawk in the field, observers should note:
- Overall tail shape – long and rounded with square corners
- Length relative to wings – reaches about 40% of the total length
- Patterning and barring – thin or thick, evenly spaced or irregular
- Colors – white, buff-brown, slate-gray, brownish-gray
The tail provides strong supportive clues but should not be the only feature used. Other key identification traits include:
- Small, compact profile
- Large head in proportion to body size
- Short, rounded wings
- Swift, acrobatic flight style
- Dark crown and bold cheek markings (in adults)
Considering all these factors together yields the most reliable identification. Proper lighting, positioning, and experience are also needed to assess fine field marks accurately.
Conclusion
A sharp-shinned hawk’s tail provides several unique identification features. The 12 graduated rectrices give the tail a long, rounded shape with squared corners. Males display thin white barring while females have thicker buff-brown bars. This patterning and shape distinguishes sharp-shins from other North American accipiters. Additionally, the tail feathers enable essential flight capabilities for this highly maneuverable hunter. Careful observation and assessment of the tail can aid in identifying sharp-shinned hawks, but should be combined with evaluation of other key characteristics.
