Rough-legged hawks (Buteo lagopus) and ferruginous hawks (Buteo regalis) are two mid-sized hawks found in North America. Both are buteos, a genus of broad-winged, soaring hawks, but they differ in their appearance, habitat, diet, and behavior. This article will compare and contrast various aspects of rough-legged and ferruginous hawks to highlight the key differences between the two species.
Physical Appearance
Rough-legged hawks are 19-26 inches in length with a 49-59 inch wingspan. Their plumage can vary from dark brown to pale brown. The most distinctive feature of rough-legged hawks is the presence of dark wrist patches or “bands” at the base of their wings when perched.
Ferruginous hawks are slightly larger at 22-30 inches in length with a 52-60 inch wingspan. Their plumage is more uniform, ranging from reddish-brown to creamy white. Ferruginous hawks lack the dark wrist bands of rough-legged hawks.
Color Morphs
Rough-legged hawks exhibit considerable color variation or polymorphism. There are three main color morphs:
- Light morph – Pale base color with dark brown spotting and streaks
- Dark morph – Chocolate brown base color with less pronounced streaks
- Intermediate/”Rufous” morph – Base color is rufous or reddish-brown
Ferruginous hawks do not demonstrate the same degree of polymorphism. Light and dark morphs exist, but the reddish-brown or “rufous” morph is not seen.
Markings
In addition to the dark wrist bands, rough-legged hawks can be identified by the following:
- Blackish “comma” shaped patches at the wrist on the underside of the wings
- Faint dark bands on the tail
- White bases on primary feathers forming a large white patch at leading edge of wing
Key markings of ferruginous hawks include:
- Lack of dark wrist patches
- Tail bands more defined and prominent than rough-legged
- Leading wing edges patterned reddish-brown
Eyes
Rough-legged hawks have yellow eyes, while ferruginous hawks have dark reddish-brown eyes. Eye color is a reliable way to distinguish these two buteos.
Habitat and Range
Rough-legged hawks and ferruginous hawks occupy different habitats and geographic ranges:
Rough-legged Hawks
- Breed in the arctic tundra zones of Alaska and Canada
- Winter in open habitats like grasslands and coastal areas in southern Canada and the lower 48 states
- Closely tied to treeless tundra habitat
Ferruginous Hawks
- Breed in open grasslands, shrublands, badlands of western North America
- Mostly year-round residents, some seasonal movements
- Avoid forested areas
Migration Patterns
The migration patterns of rough-legged versus ferruginous hawks also differ:
- Rough-legged hawks are long distance migrants – they breed in the Arctic and move south for winter.
- Ferruginous hawks are generally short distance migrants or permanent residents throughout their range.
- Rough-legged migrations cover thousands of miles from tundra to southern US and Mexico.
- Ferruginous hawk migration is limited to local movements of several hundred miles at most as they stay within the Great Plains and intermountain West.
Diet and Hunting
As predators, rough-legged and ferruginous hawks rely on different prey species:
Rough-legged Hawks
- Eat small mammals like lemmings and voles on the tundra breeding grounds.
- Switch to eating small birds, rodents and some insects during winter months.
- Hunt by coursing low over open habitats and dropping onto prey.
Ferruginous Hawks
- Eat mainly rabbits, ground squirrels, pocket gophers and mice.
- Sometimes take birds, reptiles and amphibians.
- Hunt from perches and soar high searching for prey.
Hawk Species | Primary Prey | Hunting Strategy |
---|---|---|
Rough-legged | Lemmings, voles, small birds | Low coursing flight |
Ferruginous | Rabbits, ground squirrels, pocket gophers | Perch hunting, high soaring |
Breeding and Reproduction
Rough-legged and ferruginous hawks differ in their breeding biology:
- Rough-legged hawks nest on cliffs or rocky outcrops on the tundra. Ferruginous hawks nest in trees, on rock ledges or ground.
- Rough-legged clutch size averages 4-5 eggs. Ferruginous clutch size is 2-4 eggs.
- Rough-legged hawks exhibit high mate and breeding site fidelity. Ferruginous hawks are more likely to have new mates and nest sites each year.
- Rough-legged hawks fledge their chicks in about 45 days. Ferruginous hawks fledge chicks in 38-50 days.
Conservation Status
Rough-legged hawks are relatively abundant with stable populations. Their conservation outlook is good.
Ferruginous hawk populations declined during the 20th century due to habitat loss and persecution. Their conservation status improved with protective laws. Though no longer threatened, ferruginous hawks are still considered a sensitive species.
Hawk Species | Conservation Status |
---|---|
Rough-legged | Least Concern |
Ferruginous | Near Threatened |
Conclusion
In summary, the major differences between rough-legged and ferruginous hawks include:
- Plumage – Rough-legged hawks exhibit more color variation.
- Markings – Rough-legged have dark wrist bands, ferruginous do not.
- Eyes – Rough-legged eyes are yellow, ferruginous are reddish-brown.
- Range – Rough-legged breed in the arctic tundra, ferruginous in western North America.
- Migration – Rough-legged migrate long distances, ferruginous are short distance migrants.
- Prey – Rough-legged eat small mammals and birds, ferruginous eat mammals like rabbits and ground squirrels.
- Nest sites – Rough-legged nest on cliffs, ferruginous in trees and on the ground.
- Conservation – Rough-legged are secure, ferruginous are still a sensitive species.
By understanding these key differences, bird enthusiasts can readily distinguish between rough-legged hawks and ferruginous hawks when encountering them in the field.