A red-tailed hawk is a large, common hawk that can be found throughout most of North America. Known for its reddish-brown tail and piercing scream, the red-tailed hawk is one of the most widespread and recognizable raptors in North America. As a full-grown adult, the red-tailed hawk is a sizable bird of prey, but just how heavy is a fully mature red-tailed hawk? In this article, we will explore the typical weight range of adult red-tailed hawks and what factors influence their weight.
Typical Weight Range
Most adult red-tailed hawks weigh between 2 and 3 pounds. More specifically, these medium-large raptors usually fall within the following weight ranges:
– Females: 2.4 – 3.3 lbs (1,100 – 1,500 g)
– Males: 2 – 2.7 lbs (900 – 1,220 g)
As you can see, there is some degree of sexual dimorphism when it comes to size in red-tailed hawks. This is common among raptors, with females being up to 25% larger and heavier than males on average. The increased size allows females to more easily incubate eggs and brood young nestlings.
Overall, a full-grown female red-tail generally weighs about 1/3 more than a male. But there is considerable variation across individuals, with some exceptionally large females weighing up to 4 lbs. The largest red-tailed hawk ever recorded weighed 4.8 lbs, demonstrating the extent of variation in this species.
Factors Affecting Weight
Several key factors influence the final adult weight of a red-tailed hawk:
Age
Younger red-tails are slimmer and weigh less than more mature adults. Red-tailed hawks reach full adult size at around 2 years old.Yearling hawks are typically 10-15% lighter than older adults of the same sex.
Subspecies
There are several subspecies of red-tailed hawks across North America. The subspecies Buteo jamaicensis calurus, found in the arid American southwest, is particularly large, while Buteo jamaicensis alascensis, native to Alaska, averages smaller in size. The exact body mass varies across subspecies adapted to their local environments.
Geography & Climate
Geography and climate correlate with body mass in red-tailed hawks. Birds at the northernmost and southernmost extent of the red-tail’s range, in Alaska and Central America respectively, tend to be smaller than those from temperate North American latitudes. Colder climates favor larger hawks with more insulation, following Bergmann’s rule in biology.
Availability of Prey
Abundant prey allows red-tailed hawks to regularly catch and consume food, fueling growth and a higher body weight. Sparsely populated areas with scarce prey can’t support large raptors as well. A red-tail’s diet impacts its nutrition and, consequently, its size and weight.
Health & Condition
A hawk’s health and physical condition directly impact its weight. Parasites, diseases, and injuries can depress growth and body mass. Alternatively, exceptionally fit, healthy hawks at the top condition achieve weights at the higher end of the range.
Weight by Age
Looking more closely at how a red-tail’s weight increases through maturation:
Hatchlings
Red-tailed hawk hatchlings emerge weighing about 3 ounces. Still sightless, naked nestlings grow rapidly thanks to high-protein diets of rodents, snakes, and other prey provided by their parents.
Fledglings
After 6-7 weeks in the nest, young red-tailed hawks fledge and take their first flights. At this stage, fledglings weigh 1-1.5 lbs. They remain near the nest, perfecting their flying and hunting skills as their parents continue providing food.
Juveniles
By about 10-12 weeks of age, juvenile red-tailed hawks have grown flight feathers and leave the nesting territory. Juveniles range from 1.5-2.2 lbs in weight. Over the following months, they hone their abilities, branching out farther on hunting forays.
Yearlings
After their first winter, yearling red-tailed hawks weigh around 75% of adult size as they approach sexual maturity. Yearling red-tails average 2.2-2.7 lbs.
Adults
Red-tailed hawks reach full adult dimensions at approximately 2 years old. As mentioned earlier, most adults weigh 2-3.3 lbs, depending on sex, subspecies, and other factors influencing growth. Mass stabilizes once red-tailed hawks are fully mature.
Comparison to Other Birds of Prey
To put the red-tailed hawk’s size into perspective, it’s useful to compare its weight to other common North American raptors:
Species | Average Weight |
---|---|
Bald Eagle | 6.6 – 13 lbs |
Red-Shouldered Hawk | 1.1 – 1.9 lbs |
Broad-winged Hawk | 0.8 – 1.3 lbs |
Cooper’s Hawk | 0.8 – 1.5 lbs |
Red-tailed Hawk | 2 – 3.3 lbs |
The bald eagle is the only bird of prey in North America that is definitively larger and heavier than a red-tailed hawk. Other buteos like the red-shouldered and broad-winged hawks are smaller. The Cooper’s hawk is a similar sized accipiter hawk that may overlap the lower end of the red-tail’s weight range. Overall, the red-tailed hawk is a solidly medium-large raptor, heavier than most other hawks it encounters within its range.
Uses of Knowing a Red-Tail’s Weight
So why does accurately gauging a red-tailed hawk’s weight matter? There are several useful applications for this information:
Field Identification
Knowing expected red-tail weights helps birders promptly identify these hawks in the field. If an unknown buteo is clearly outside the typical red-tailed weight range, it must be a different species. Weight estimates contribute clues for proper identification along with other features.
Tracking Growth & Development
Wildlife rehabilitators and falconers must monitor weight to assess whether young raptors in their care are growing properly. A stunted growth rate and low body weight can signal health or nutrition issues requiring intervention.
Evaluating Condition & Health
A hawk’s weight offers important context on its physical condition. Rapid weight loss may indicate illness or injury. Comparing weights over time tracks impacts of diseases and recovery progress with treatment.
Studying Populations
Scientists capture, measure, band, and release red-tailed hawks to study wild populations. Weight data collected complements other biometrics to analyze geographic variations, life history traits, and demographic patterns, contributing to comprehensive population studies.
Selecting Equipment
For falconers, knowing a hawk’s weight ensures proper sizing of jesses, anklets, hoods, and other falconry gear fitted specifically for that bird. Proper equipment sizing maximizes comfort and training.
Weighing a Red-Tailed Hawk
While many hawks must be captured and handled to determine their exact weight, there are a couple non-invasive methods that provide reasonable weight estimates for wild red-tailed hawks:
Visual Size Estimation
With practice, observers can visually estimate a red-tail’s size and correlate this to expected weight ranges. Comparing relative sizes and proportions to other hawks provides clues. However, visual size estimation lacks precision and should be supported by other context.
Photogrammetry
Analyzing a photograph of a red-tail can yield a surprisingly accurate weight estimate. Comparing the hawk’s total length relative to familiar objects in the image allows a reasonable weight calculation. Photogrammetry has become a popular technique for researchers to remotely assess wild raptors.
Overall, weighing requires capturing hawks safely using traps, nets, or falcons. This should only be attempted by experienced, permitted biologists and falconers. For casual birders, visual cues and photography provide suitable weight approximation in most cases.
Why Red-Tailed Hawks are Heavyweight Hunters
Now that we’ve explored how much a full-grown red-tailed hawk weighs, it’s worth discussing why these birds are heavyweight predators compared to most other raptors:
They Hunt Large Prey
A red-tail’s heavy weight suits its diet of fairly sizable prey, including rabbits, ground squirrels, and even smaller deer. Lightweight raptors couldn’t reliably kill and carry such substantial prey.
They Soar for Hours
Heavier birds soar more efficiently on thermal updrafts. Red-tails utilize soaring flight to locate prey and migrate over long distances. Lower body mass would hinder their expansive daily movements.
They Need Insulation
Bulkier body size provides insulation against cold weather for a hawk ranging through northern latitudes. Lighter raptors like falcons can’t retain heat as effectively in frigid conditions.
They Defend Expansive Territories
A red-tail’s large territory ensures adequate food resources. Imposing size deters intrusion from competitors. Smaller hawks lack the commanding presence to claim such extensive areas.
They Nest in Exposed Sites
Sturdy stick nests high on cliffs or in open trees rely on the red-tail’s brawn and balance to access. More petite raptors nest in forest cavities or other sheltered spots.
They Dominate Other Hawks
A heavyweight red-tailed hawk asserts its physical dominance over smaller buteos, accipiters, and falcons across shared hunting grounds. Its bulk conveys greater fighting prowess.
They Can Tackle Formidable Prey
With greater strength and body mass, red-tails can capture dangerous prey like venomous snakes and mid-sized furbearers that pose risks to lighter raptors. Their size reduces risk of injury.
In summary, the red-tailed hawk’s characteristic heavyweight stature provides diverse ecological advantages. These versatile apex predators owe their success across habitats to exceptional bulk and power for a medium-sized raptor.
Conclusion
A full-grown red-tailed hawk typically weighs between 2 and 3.3 pounds. Most females weigh about 1/3 heavier than males on average. Several factors like age, subspecies, geography, nutrition, and health influence the final adult mass. Heavier body weight benefits red-tails in hunting large prey, soaring flight, weather resilience, territoriality, nesting, and dominance over smaller raptors. Estimating a wild red-tail’s weight aids identification and evaluating condition, growth, and populations. Overall, the red-tailed hawk is ideally sized to thrive as a powerful predator across North America.