The Ferruginous Hawk is a large bird of prey found in the open grasslands and desert regions of North America. It goes by several other common names including Ferruginous Rough-leg, Ferruginous Rough-legged Buzzard, and Squirrel Hawk. Its scientific name is Buteo regalis. This impressive raptor has dark brown upperparts and bright white underparts with reddish leg feathers, giving rise to its name “ferruginous” which means rusty iron color in Latin. The Ferruginous Hawk is the largest hawk species found in North America and can have a wingspan exceeding 5 feet. It is a powerful hunter able to take down small mammals like ground squirrels, prairie dogs, and rabbits which led to one of its common names, the Squirrel Hawk. While widely distributed across the central plains, prairies, and arid lands of western North America, the Ferruginous Hawk has experienced population declines due to habitat loss and is considered a Species of Concern by many states and conservation groups. Understanding its naming origins, physical characteristics, habitat, hunting skills, conservation status, and other traits can help appreciate the importance of this iconic bird of prey.
Common and Scientific Names
The Ferruginous Hawk goes by several common names that speak to its rusty-colored plumage and skills as a predator.
Ferruginous Rough-Leg and Ferruginous Rough-Legged Buzzard
These names reference the hawk’s legs which are covered in distinctive reddish-brown feathers. The term “rough-leg” was used for several large hawks including the Ferruginous, Red-tailed and Swainson’s Hawks that all shared the trait of feathered legs as opposed to bare legs.
Squirrel Hawk
This name points to the Ferruginous Hawk’s prowess at hunting small rodents like ground squirrels and prairie dogs which are a major part of its diet. It is a powerful and agile hunter capable of swooping down to snatch a squirrel off the ground in its deadly talons.
Buteo regalis
The scientific name Buteo regalis translates to “regal buzzard” or “regal hawk”, likely in reference to its large size compared to other raptors. Buteo is a genus of broad-winged hawks and regalis comes from “rex” meaning king or ruler in Latin.
Physical Description
The Ferruginous Hawk is North America’s largest hawk species and is powerfully built with broad wings and a large head.
Size
Ferruginous Hawks measure 20-26 inches in length with average wingspans of around 5 feet, but they can reach up to 6 feet across. They weigh between 2.5-4.5 pounds.
| Measurement | Range |
|---|---|
| Length | 20-26 in (50-65 cm) |
| Wingspan | 48-72 in (120-180 cm) |
| Weight | 2.5-4.5 lb (1,130-2,035 g) |
Plumage
Adult Ferruginous Hawks have dark brown backs, wings and heads which contrast sharply with their snowy white underparts. Their shoulders, legs and underwing feathers are a rusty reddish-brown color. The tail has pale bands and a white tip. Juveniles have less contrast with streaky brown bellies and light feather edges.
Sexual Dimorphism
Females Ferruginous Hawks are significantly larger than males. Females weigh approximately 25% more than males on average.
| Sex | Average Weight |
|---|---|
| Female | 3.1 lb (1,400 g) |
| Male | 2.4 lb (1,100 g) |
Habitat
The Ferruginous Hawk inhabits the open grasslands, sagebrush flats, desert regions and prairies of western North America.
Grasslands
Grasslands with low vegetation provide ideal hunting grounds for these birds to spot and pursue rodent prey. They avoid forests and woodlands.
Arid Lands
Badlands, semi-desert shrublands and desert grasslands are common habitats, particularly in the Southwest.
Range
Their breeding range covers much of the central plains from the Rocky Mountains to the Mississippi River. They are found as far north as Alberta, Canada and south to Texas and Mexico.
Nesting
Ferruginous Hawks nest on cliffs, bluffs, rock outcroppings, trees and utility structures. Nest height is often 30-50 feet high.
Diet and Hunting
With excellent eyesight and speed, Ferruginous Hawks hunt mainly small mammals but will also take birds, reptiles and large insects.
Primary Prey
Ground squirrels, prairie dogs and pocket gophers make up 60-90% of their typical diet. Rabbits and kangaroo rats are also common prey.
Hunting Techniques
The hawk hunts by soaring at height to scan for prey then diving swiftly to strike with its talons. It may also search for prey while flying low over the ground or from an elevated perch.
Prey Size
Prey animals usually weigh between 1-3 pounds with the largest recorded prey being a rabbit weighing 6 pounds.
| Prey Type | Examples |
|---|---|
| Mammals | Ground squirrels, prairie dogs, pocket gophers, rabbits, rats, voles, deer fawns |
| Birds | Quail, grouse, horned larks, blackbirds |
| Reptiles | Snakes, lizards |
| Insects | Grasshoppers, crickets |
Breeding and Life Cycle
The breeding season for Ferruginous Hawks ranges from early March to late August, depending on their geographic location. They are monogamous and mate for life.
Courtship
Courtship displays include the male performing dramatic dives and aerial maneuvers and offering prey to the female. Ferruginous hawks do not build their own nests. They use abandoned stick nests, ledges or depressions on bare ground.
Eggs and Incubation
The female lays 2-8 eggs which hatch after about 32 days of incubation. The female does most of the incubating while the male provides food. After hatching, both parents feed and care for the young.
Fledging
Chicks fledge at around 6-7 weeks, remaining dependent on the parents for food and training for several more weeks. They reach reproductive maturity at around 3 years old. Ferruginous Hawks may live 12 years or more in the wild.
Conservation Status
With declining populations due to habitat loss, the Ferruginous Hawk is considered a threatened, endangered or species of special concern in many parts of its range.
Population Trends
Ferruginous Hawk numbers decreased significantly in the 20th century as prairie lands were converted to agriculture. They rebounded partially with reduced pesticide use but remain at risk.
| Region | Population Trend |
|---|---|
| Global | Decreasing |
| United States and Canada | Likely stable |
| Mexico | Decreasing |
Threats
Habitat loss, motor vehicle collisions, illegal shooting, disturbance of nest sites, and collisions with power lines and wind turbines pose risks. Agricultural pesticides reduce their food supply.
Conservation Status
The Ferruginous Hawk is considered a Species of Concern in multiple states. It is listed as Threatened in Canada and Endangered in Mexico. Conservation measures include habitat protection, nest monitoring, public education, and reducing rodenticide use.
Interesting Facts
Largest Hawk in North America
With a wingspan rivaling a Bald Eagle’s, the Ferruginous Hawk reigns as the largest hawk on the continent.
Specialized Feet
A large rear talon allows them to efficiently kill prey by puncturing the neck or head. Their feet are also feathered to protect against cold in northern areas.
Voice
Their vocalizations include a kree-eee-ar call used for territorial displays. Falcons may mimic this call to trick Ferruginous Hawks and steal their prey.
Native American Lore
Some Native American tribes considered the Ferruginous Hawk a sacred messenger between gods and people. Spotting one was thought to bring spiritual messages.
Conclusion
With its rusty colored legs and shoulders, immense size and skillful hunting abilities, the Ferruginous Hawk stands out as one of North America’s most formidable birds of prey. This iconic raptor of the open prairies and desert lands has earned many intriguing common names like Squirrel Hawk and Ferruginous Rough-leg that reflect its appearance and lifestyle. While revered by many indigenous cultures, the Ferruginous Hawk now faces threats from habitat loss and modern industrialization. Increased conservation measures aimed at protecting these majestic hawks will be crucial to preserving them for future generations. The regal Ferruginous Hawk remains a symbol of the wild and untamed spirit of the Western plains.
