Red-tail hawks are one of the most common and widespread hawks in North America. They are large, broad-winged birds of prey that can be found in a variety of habitats including woodlands, farms, highways, and suburban areas. Red-tails go through several distinct life stages on their journey to adulthood. Here is an overview of the red-tail hawk’s development and how long it takes them to reach their full size.
Egg Stage
The egg stage begins when a breeding pair of red-tail hawks construct a nest of sticks high up in a tree or on a cliff ledge. The female hawk then lays between 1 to 3 eggs over a period of several days. The eggs are whitish in color with brown speckles or blotches. They are approximately 2 inches long and 1.5 inches wide. The female hawk will then incubate the eggs for 28 to 35 days before they hatch.
Nestling Stage
Once the eggs hatch, the newborn hawks are known as nestlings or eyases. They are covered in white downy feathers and their eyes are closed. They are helpless and completely dependent on their parents for food, warmth, and protection. For the first week, the female broods the nestlings while the male brings food to the nest. Nestlings grow rapidly thanks to the protein-rich diet provided by their parents. Within 5 to 6 weeks, the nestlings will increase their body weight by a factor of 10! Their flight feathers start growing within 2 to 3 weeks. By 6 weeks, the juveniles are almost as large as their parents but their tail and flight feathers are not fully grown.
Fledgling Stage
At around 6 weeks, the juvenile hawks will make their first flight from the nest, known as fledging. However, their flying skills are clumsy and limited at first. They hop from branch to branch while their flight feathers continue developing. The parents continue to provide food for the fledglings. From 7 to 10 weeks, the young hawks improve their flying abilities and start hunting prey on their own close to the nest site. Their distinctive red tail feathers begin growing in at around 2 months old.
Juvenile Stage
From 3 to 4 months old, the young red-tails are considered juveniles. Their tail feathers and wings are fully formed but they still have some fluffy down on their heads and bodies. They gradually venture further away from the nest and improve their flying and hunting skills. Juveniles have blue-grey eyes while adult red-tails have brown eyes. The eye color change occurs between 4 and 6 months old.
How Long Until Fully Grown?
Most sources state that red-tailed hawks reach their full adult size by around 2 months old. However, their plumage continues maturing until they are about 1 year old. Here is a growth timeline for red-tailed hawks:
Age | Developmental Stage |
---|---|
1 week | Nestling phase. Covered in white down, eyes closed. |
3 weeks | Nestling phase. Flight feathers starting to grow. |
6 weeks | Fledgling phase. Leave the nest for first flight. |
2 months | Juvenile phase. Reach full adult size. |
3-4 months | Juvenile phase. Tail fully formed. |
1 year | Reach full adult plumage. |
So in terms of size, red-tails are considered fully grown around 2 months old. Their plumage and eye color continues maturing until 1 year old when their coloration matches adult hawks. Females are larger than males, but both reach full size by 2 months of age.
Factors Affecting Growth Rate
While the average red-tail reaches maturity at 2 months, their actual growth timeline can vary based on several factors:
- Nutrition – Well-fed nestlings grow faster than malnourished hawks.
- Birth order – The first hatchlings tend to develop quicker than later hatchlings.
- Weather – Cold temperatures or storms may slow growth.
- Injury/illness – Any health issues can inhibit normal development.
- Species – Some subspecies like Harlan’s hawk mature slightly faster.
- Gender – Females normally grow quicker than males.
With ideal conditions, red-tails can reach their full size at the younger end of the range. But environmental stressors may delay their growth at the slower end of averages. Regardless, most red-tailed hawks will achieve their mature stature by 2 months of age.
Growth Rate
The rapid growth of red-tailed hawk nestlings is incredible. Hatchlings weigh about 3 ounces at birth. By the time they fledge at 6 weeks old, they weigh 2.2 to 3.3 pounds! Here are some typical growth benchmarks for red-tailed hawk nestlings:
Age | Average Weight |
---|---|
Hatching | 2.8 ounces |
7 days | 7 ounces |
14 days | 14 ounces |
21 days | 1.1 pounds |
28 days | 1.9 pounds |
Fledging (42 days) | 2.2 – 3.3 pounds |
Their rapid weight gain is fueled by the protein-rich diet supplied by their parents. Hawks may eat the equivalent of their own body weight each day while growing. Given this tremendous growth rate, it’s no wonder red-tails achieve adult size by just 2 months of age.
Wingspan Development
In addition to weight, the wingspan provides another indicator of red-tail development. Newly hatched eyases have no real wings to speak of. But their flight feathers begin emerging within 2 to 3 weeks. Here is the timeline for fledgling red-tail wingspan growth:
- 2 weeks – 3 inches
- 3 weeks – 6 inches
- 4 weeks – 12 inches
- 5 weeks – 24 inches
- 6 weeks – 34 inches
- Adult – 48 inches
It’s remarkable that they go from stubby 3 inch wings to a nearly 3 foot wingspan in just a month and a half. This rapid wing growth allows young red-tails to start flying at 6 weeks of age. The wings continue expanding to full adult size by 2 months old.
Leg and Foot Growth
The legs and feet of red-tailed hawks also undergo rapid development. At hatching, the legs are disproportionately long compared to the body. The feet have an oversized look but this helps provide stability in the nest. Within weeks, the body size catches up and the legs slim down. The feet gradually become more muscular to allow for grabbing prey. Here are some key milestones:
- Hatching – Legs and feet are large but weak
- 2 weeks – Legs thinning, feet still oversized
- 4 weeks – Legs and feet proportional to the body
- 6 weeks – Talons and feet capable of holding prey
- Fully grown – Strong muscular legs and sharp talons
The red-tail’s legs and lethal talons are vital for capturing and feeding on prey. Their development coincides with the hawk’s increasing hunting skills and independence after fledging.
Growth Rate Compared to Other Hawks
Red-tailed hawks grow from helpless hatchlings to accomplished hunters within a span of just 6 to 8 weeks. This growth rate is impressive compared to many other hawk species. Here’s how the red-tail’s development compares:
Species | Fledging Age | Reaches Adult Size |
---|---|---|
Red-tailed Hawk | 6 weeks | 2 months |
Cooper’s Hawk | 4 weeks | 3 months |
Sharp-shinned Hawk | 3 weeks | 3 months |
Northern Goshawk | 4 weeks | 3 months |
Broad-winged Hawk | 5 weeks | 3 months |
You can see that most hawks fledge sooner than red-tails, but take equally long or longer to reach maturity. Red-tails strategically invest more time developing in the nest before fledging. This helps explain their rapid mastery of flight and hunting compared to other juvenile hawks who are less skilled initially after fledging.
Conclusion
In summary, red-tailed hawks undergo a dramatic growth transformation in a short time period. From helpless hatchlings to accomplished hunters in about 2 months! While the timing varies slightly, the key milestones in their development are:
- Hatch from eggs at 4 weeks
- Fledge from nest at 6 weeks
- Reach full adult size by 2 months
- Achieve mature plumage by 1 year
The red-tail’s rapid yet strategic growth allows it to learn critical survival skills while still being cared for by its parents in the nest. This sets red-tails up for success once they fledge and continue honing their hunting abilities as juveniles. The red-tail’s resilience and adaptability are evident in its diverse habitats across North America.