Ferruginous hawk– Boda rhyng goch
Order accipitriformes
family accipitridae
Genus Buteo (buteonine hawks, and buzzards. they are not true hawks )
Ferruginous buzzard, commonly known in America as the ferruginous hawk are medium to large raptors of the west and northern plains, residing in open country, interior in lowlands, plateaus, valleys, and edges of deserts, following vast expanses of sage bush prairie and grasslands in the summertime, and in the winter move to agricultural areas.
Ferruginous hawks are migratory, particluarily in northern most populations and move south for the winter, though some individuals may remain in their breeding grounds if prey is available. Most ferruginous hawks participate on broad front migration to warmer areas in the central/southern U.S and Mexico, leaving breeding grounds late summer and returning in spring, which is heavily influenced by food availability.
Broad-front migrants do not follow narrow traditional flight paths like other raptors, but rather they spread out over wider areas. they travel an average 2,300km, which is roughly 1,400miles with significant variation utilizing ground based hunting strategies,
The ferruginous hawk is the largest buteo in North America, with behaviors giving it the name of the Prairie eagle, and was once referred to as a small eagle, and received its name the royal hawk (Buteo regalis) for its size. some females are twice the weight of the males.
The key differences between ferruginous hawks and eagles are firstly their size and weight.
Ferruginous hawks weigh 2-4lbs, buteos tend to max out at 3.5lbs, when hunting from hilltops, and powerpoles scanning for prey, however, they do appear a very bulky raptor on average.
Eagles weigh up to 10lbs on average
Flight and shape differences
Ferruginous hawks, like buzzards, hold their wings in a distinct shape soaring in wide circles in a dihedral v position, tilting up from the body to the wingtips, enhancing lateral stability and creating more lift on the lower wing point when turning on the soar, especially when rolling left or right. A self correcting mechanism. A very much helps us to identify buzzards from hawks and eagles within the same order. They have labored stiff wingbeats, quicker on the deep upstroke than that of eagles and redtail hawk ( buteo), which the later is more snappy in flight. the ferruginous buzzard has a large 4-5ft wingspan.
The ferruginous hawk is less common than the rough legged buzzard and redtail buzzards, but are more visible in the winter and summer months, and some wintering birds have been noted to roost up to 100 birds mixing with red tailed buzzards and rough legged buzzards.
They are very Buoyant in flight too for a raptor, flights have been resembled to that of northern harriers, but with less of a wobble. they are capable of high speed hunting dives of up to 150mph, dropping from high altitudes and swooping from perches using their immense buteo bodyweight, especially when catching jack rabbits, to suprise their prey in fast swooping low level flights. this species will also hover and kite in the wind equally. and have excellent vision to spot their prey at burrow entrances.
Talon grasp also differs to eagles.
The ferruginous hawk is known to grasp prey with a force of 200psi, as an example bald eagles force is much stronger at around 400-450psi
head and beak.
The ferruginous buzzard has a very large flat head to body size, with a noted very large gape, for swallowing prey such as ground squirrels very quickly to prevent food theft from predators.
Natural predators
Golden eagle the primary threat to adult and young ferruginous hawks during territorial disputes
great horned owl, preys on nestlings, fledglings, and sometimes adults at night
Coyotes a significant threat to ground nesting pairs and young
Bobcats threaten young hawks at ground nests
Raccoons depredate nestlings in tree nests
Common raven preys on eggs and young in nests
American badger threat to ground nesting birds
Swainson’s hawk competitor and aggressor for nesting sites
red tail hawk compete for similar prey and nesting territory
great horned owl, besides predation, they often steal and reuse nests built by ferruginous hawks
In the summertime their diet consists mainly of ground squirrels, pocket gophers, and prairie dogs, rabbit, mice, as well as birds like the western meadow lark,and sometimes sage grouse and reptiles , to include snakes. and doing so mostly on foot for the ground dwelling and burrowing mammals, highly specialized for open grasslands and prairies, running and walking and waiting at burrow entrances to catch prey. This is unusual strategy for many North American buteos. They will also steal prey from other raptors and will scavenge too.
During the winter they have been observed in groups of 5-10 foraging in areas with high prairie dog populations.
The ferruginous buzzard is known for its plumage, and rusty feathered pants, sometimes referred to as rusty chaps. ferruginous relates to rust colored, and refers to this raptors reddish brown feathers on its legs. this species is unique for having feathered legs that extend to its toes resembling pants and this is named as booted and they are the only American hawk with feathered legs.
In flight they are easily identified by the red colored V, against their white underside. tapering primary feathers longer than tail.
The ferruginous hawks are common in two color morphs
common-light, white and silver grey, with rusty patches on back and shoulders, white, rust and silver grey colored tail.
and a darker morph
However all morphs have whitish grey flight feathers.
Big buteo little voice
Their call is suprizingly weak and high pitched
Nesting
Ferruginous buzzards favor vast expanses with good lookout perches, they nest in large trees, upon power poles and even on the ground, and are very shy raptors, and easily disturbed by human activity.
Ferruginous hawks are sexually diamorphic, the female one and a half times larger than the male
When courting, ferruginous buzzards will soar with wings held arched over their backs, the male then darts at the female, and their talons grasp which then turns to a aerial cartwheel display. a pair of hawks mate for life.
Average age at reproductive maturity
female 730 days
male 730days.
Nest structures are consisted of sticks 1 inch in diameter, cow dung, bones and grass.
they lay 2-4 bluish white eggs marked with brown and even sometimes up to 8 in high prey density areas
They produce 1 clutch per season, and if this fails, due to human activity or predation they do not produce a second clutch and will abandon the area. and are of conservation assessment with regard to this.
Incubation 28-33 days
Average size of egg 61mm
Parents will share the responsibility of feeding the young until they become independent.
Ferruginous buzzard chicks are noted to leave the nest early if disturbed or down to hot environmental factors where they will seek out shade, adults will also abandon them, nestlings are mobile at an early age of 18-20 days, and can hunt and capture food such as reptiles insects, small mammals like mice around 40 days, however there are great risks around this age. Data on hatchling sex ratio of this species indicates a skew towards males at the time of fledging, with sex ratios varying between years, suggesting environmental factors, such as prey availability, likely to influence sex allocation. Reproductive success is highly correlated with the availability oF Richardson’s ground squirrels. This prey base influences the breeding density as well as influencing sex ratio of the nestlings. whilst many bird species have a 50:50 hatchling sex ratio, the observation of male biased ratio in ferruginous buzzards suggests that, similar to other raptors they may experience sex specific mortality or have mechanisms that favor the smaller sex ( males) to reduce the cost of raising young during potential resource scarcity.
Status
Ferruginous buzzard population is of concern across much of its range with an estimated population of less than 4,000 breeding pairs in the western united states, their numbers have declined due to habitat loss, prey reduction, fire degraded habitat, contaminants, collisions and disturbances and nest abandonment, and also considered a species of concern in Canada, declining since the 1990s in like Alberta, though conservation efforts like installing nesting platforms are aiding local recovery. whilst populations have historically decreased, localized conservation efforts and increased awareness are protecting these nesting sites to help maintain populations in some regions.
Number of mature individuals-
86,000-110,000, classed as least concern ICUN (this is due to criteria for vulnerable listing has to be under 10,000 mature individuals with a decline of 10% in ten years, or 3 generations) With an extent ocurrance 3,320,000km, an extremely large range, and therefore does not approach the thresh holds of vulnerable under this range size criteria either ( extent of ocurrance under 20,000 kmsq, combined with a declining or fluctuating range size.)
This species, with a low breeding pair count, however, has undergone a large and statistically significant increase over the last 40 years in North America with an 155% increase, equating to a 26 % increase per decade.
Population assessments therefore class this species as stable
average lifespan wild 20 years, we have a female named bonnie, who is 26 presently.