Red-tailed hawks are one of the most common and widespread hawks in North America. They are large, stocky birds of prey that can be identified by their distinctive reddish-brown tails. Juvenile red-tailed hawks are smaller and less colorful than adults, but they grow rapidly to reach full size within their first year.
Some key facts about the size of juvenile red-tailed hawks:
- Wingspan at hatching: 27-31 cm (10.5-12 inches)
- Length at hatching: 7-8 cm (3 inches)
- Weight at hatching: 60-80 g (2-3 oz)
- Wingspan at fledging: 101-127 cm (40-50 inches)
- Length at fledging: 48-56 cm (19-22 inches)
- Weight at fledging: 900-1400 g (2-3 lbs)
Read on for more details on how juvenile red-tailed hawks grow and develop to reach their impressive mature size.
Size at Hatching
Red-tailed hawks hatch from their eggs after an incubation period of about 35 days. Newly hatched chicks are covered in white down feathers and are quite small compared to the mature hawks they will become.
Some key size parameters for red-tailed hawk chicks at hatching are:
- Wingspan: 27-31 cm (10.5-12 in)
- Length (bill to tail): 7-8 cm (3 in)
- Weight: 60-80 g (2-3 oz)
Their wings are small nubs, and their eyes are closed at first. Their bill and talons are soft and not fully developed. They are essentially helpless at this stage and rely completely on their parents for food and protection.
Appearance
Newly hatched red-tailed hawks are covered in fluffy white down. Their bodies are round and compact. They have disproportionately large feet and heads.
Their wings are small stubs at this point, not usable for flight. The wingspan of 27-31 cm is less than half of what it will eventually become.
Their tails are also short, around 2.5-5 cm (1-2 inches). The distinctive reddish-brown tail that gives the species its name will not appear until they mature.
Growth Rate
Red-tailed hawk chicks grow rapidly right from hatching. They typically gain about 20-30 g (0.7-1 oz) per day at first. Within two weeks of hatching, they often double their hatching weight.
Their wings and tails also grow quickly, starting out as nubs but soon becoming useful for getting around the nest. Their eyes open at around 5-7 days old.
By two weeks old, red-tailed hawk chicks are covered in juvenile feathers and are starting to look more like miniature versions of adults. Their growth rate continues to accelerate up to fledging.
Size at Fledging
Red-tailed hawk chicks are considered fledglings once they leave the nest, which occurs 5-6 weeks after hatching. By this point, they have grown tremendously but still have a way to go to reach mature size.
Some key size stats for red-tailed hawks at fledging:
- Wingspan: 101-127 cm (40-50 in)
- Length: 48-56 cm (19-22 in)
- Weight: 900-1400 g (2-3 lbs)
Appearance
Fledged juvenile red-tailed hawks have most of the physical features of adults. Their bodies are fully feathered in brown and white plumage. Their wings are large and broad, suitable for extensive flights.
Their tails have grown to about 15-20 cm (6-8 inches) and started to show some red coloring. Their legs and feet are yellow, and their talons are black and fully developed.
One key difference is their heads are mostly brown rather than white like adults. Their eyes are pale yellow rather than deep red. Their colors will continue to mature as they grow.
Flight Capabilities
By the time they fledge, juvenile red-tailed hawks have enough wing surface and power to be capable fliers, although they may still be a bit unsteady and awkward at first.
They use their flying abilities to leave the nest and follow their parents to learn hunting skills. Fledglings cannot hunt effectively at first and still depend on their parents for food in the early weeks after fledging.
Growth Rate
In the roughly 5 weeks between hatching and fledging, red-tailed hawk chicks increase their weight almost 20 times over. Their wingspans grow to 4-5 times the hatching size.
This intense growth rate levels off after fledging. They continue increasing size and honing their flying and hunting skills until reaching full maturity.
Size at Maturity
Red-tailed hawks are considered mature after their first year, once they complete their first molt cycle. At this point, they reach their full adult size and colors.
Some typical size measurements for mature red-tailed hawks are:
- Wingspan: 114-137 cm (45-54 in)
- Length: 52-65 cm (20-26 in)
- Weight: 910-1450 g (2-3.2 lbs)
Of course, size ranges are broad for this species. Especially large individuals may have wingspans up to 152 cm (60 in) and weigh over 1.8 kg (4 lbs).
Differences from Juveniles
Besides being larger overall, mature red-tailed hawks can be distinguished from juveniles by:
- White head and breast instead of mostly brown
- Reddish tail around 25 cm (10 in) long
- Deep red eyes instead of yellow
- More vivid and distinct plumage patterns
Their capabilities are also much greater than juveniles. They are accomplished, efficient hunters with mastery of flight and aerial attack maneuvers.
Range of Sizes
There is some natural variation in the size of mature red-tailed hawks. Females tend to be larger than males, but there is overlap between the sexes. Some key influences are:
- Genetics – Some individuals are genetically predisposed to be larger
- Food availability – Abundant prey allows reach larger size
- Habitat – Hawks in open habitats are often bigger
- Subspecies – Ranges from small Southwest forms to large Northern ones
The tables below show some size measurements for the sexes and subspecies:
| Measurement | Male Size Range | Female Size Range |
|---|---|---|
| Wingspan | 109-137 cm | 119-150 cm |
| Length | 48-61 cm | 54-68 cm |
| Weight | 700-1300 g | 1000-2000 g |
| Subspecies | Wingspan |
|---|---|
| B. j. calurus (Western) | 99-114 cm |
| B. j. alascensis (Alaskan) | 127-142 cm |
| B. j. borealis (Northern) | 122-150 cm |
| B. j. kriderii (Prairie) | 114-137 cm |
Growth Rate
The dramatic growth of red-tailed hawks from hatching to maturity is fueled by their voracious appetite. These raptors are powerful hunters with high metabolic rates. Here are some key facts about their growth rates:
- Peak growth occurs 2-6 weeks after hatching, up to 50 g (1.8 oz) per day
- Slows down after 8 weeks but continues 3-4 months after fledging
- Reaches 98% of mature mass by 1 year old
- Growth rate higher in females since they grow larger
- Better food supply = faster growth
This chart summarizes the mass gain of red-tailed hawks from hatching to maturity:
| Age | Mass (g) |
|---|---|
| Hatching | 60-80 |
| 2 weeks | 250-350 |
| 4 weeks (fledging) | 900-1400 |
| 3 months | 1100-1700 |
| 1 year (mature) | 1000-2000 |
This represents more than a 20-fold increase in body mass from hatching to maturity in the first year of life.
Factors Influencing Growth
The major factors that influence a red-tailed hawk chick’s growth rate include:
- Genetics – Individual variance in growth potential
- Food availability – More food energy means faster growth
- Number of siblings – Less competition allows greater growth
- Parental care – Good hunting and feeding by parents helps growth
- Health – Disease or injury can slow growth
- Weather – Colder weather necessitates more energy for warmth
In good conditions with plentiful food and low competition, red-tailed hawks can reach the top end of the growth rate ranges. Poor conditions lead to slower growth.
Developmental Stages
Red-tailed hawks go through distinct developmental life stages on their way to maturity. The timing of these stages can vary somewhat based on factors like nesting timing and number of siblings.
Hatchling (0-2 weeks)
- Rapid growth of body mass and wings
- Covered in white down
- Eyes closed at first, open within 1 week
- Limited mobility, parents provide food
Nestling (3-6 weeks)
- Juvenile plumage develops
- Increasing motor skills and mobility in nest
- Able to tear up prey brought by parents
- Rapid growth continues
Fledgling (6 weeks – 3 months)
- Leave (fledge) nest at 6-7 weeks
- Parents still provide most food
- Develop flight skills and strength
- Some plumage still juvenile
Immature (3-12 months)
- Independent hunting but still developing skills
- Mature plumage develops
- Grows to full adult size
- Disperses from parents’ territory
Mature Adult (after 1 year)
- Reaches sexual maturity
- Establishes own breeding territory
- Full adult plumage and capabilities
This sequence allows red-tailed hawks to grow and gain skills in distinct phases before reaching full maturity and independence.
Comparison to Other Hawk Species
Red-tailed hawks are a large Buteo species. Their size can be compared to some other common North American hawks:
| Species | Length (cm) | Wingspan (cm) | Weight (g) |
|---|---|---|---|
| Red-tailed Hawk | 48-65 | 109-150 | 700-2000 |
| Red-shouldered Hawk | 43-58 | 105-127 | 500-1200 |
| Broad-winged Hawk | 36-46 | 95-110 | 425-775 |
| Sharp-shinned Hawk | 29-35 | 58-71 | 85-210 |
As this comparison shows, red-tailed hawks are substantially larger than “sharpie” sharp-shinned hawks. They are also bigger on average than the related red-shouldered hawks, although size ranges overlap.
Only eagles and ferruginous hawks are clearly larger than red-tails among North American Buteos. The red-tail’s combination of size, strength, and aerial agility make it a formidable predator.
Conclusion
Juvenile red-tailed hawks hatch small but grow rapidly. Within their first year, they reach full mature size and capabilities.
Key size benchmarks include:
- Hatching: 7-8 cm long, 27-31 cm wingspan, 60-80 g weight
- Fledging (6 weeks): 48-56 cm long, 101-127 cm wingspan, 0.9-1.4 kg weight
- Maturity (1+ year): 52-65 cm long, 109-150 cm wingspan, 0.7-2 kg weight
Their growth rate is affected by factors like nutrition and genetics. Given adequate food resources and low sibling competition, juveniles can reach the upper ranges of the size scales within their first year.
The red-tailed hawk’s large size, broad wings, sturdy build, and powerful talons make it highly effective at catching and killing rodents and other prey. Their impressive growth allows juveniles to quickly gain the size and skills needed to become formidable hunters.
