Goshawks are large, powerful raptors that belong to the Accipitridae family. They are formidable predators that hunt birds and mammals in woodland habitats. Of the two goshawk species, the Northern Goshawk (Accipiter gentilis) is larger and the focus of this article.
Male Northern Goshawks are substantially bigger than females. This reversed sexual dimorphism means males have physical advantages for defending nesting territories and procuring food. But exactly how big are male Northern Goshawks? Let’s look at some key size measurements.
Wingspan
The wingspan is the distance from the tip of one wing to the tip of the other, measured when the wings are fully extended. This gives a sense of the aerial size of a bird.
For male Northern Goshawks, the average wingspan is 110-115 cm (around 3.6-3.8 feet). This is over 20% larger than the average female wingspan of 90-105 cm (around 3.0-3.4 feet).
The male’s greater wingspan aids speed, maneuverability, and power in flight when chasing prey or displaying in breeding rituals. Their broad wings enable agile darting through dense forests.
Body Length
Body length is measured from the tip of the beak to the tip of the tail.
Male Northern Goshawks have an average body length of 55-65 cm (around 22-26 inches). Females are smaller at 45-60 cm (around 18-24 inches).
The male’s greater body length reflects their larger overall size and bulk. This gives them an advantage in territorial fights against rival goshawks. Their size also helps them overpower sizeable avian prey like grouse.
Weight
The average weight of a male Northern Goshawk is around 1,100 g (2.4 lb). However, weights range from around 770 g (1.7 lb) at the small end up to around 1,600 g (3.5 lb).
In comparison, female Northern Goshawks weigh 700-1,500 g (1.5-3.3 lb) on average.
The considerable bulk and power of the male helps them defend nesting sites and capture prey. Even relatively small mammals like squirrels and rabbits can be overwhelmed by an adept, hefty male goshawk.
Tail Length
Male Northern Goshawks have a tail of around 28-36 cm (11-14 inches) in length. The female’s tail is a bit shorter at 24-33 cm (9.5-13 inches).
The goshawk’s relatively long tail aids maneuverability and braking when flying through cluttered forests in pursuit of prey. The male’s marginally longer tail assists with aerodynamic agility.
Leg Size
Male Northern Goshawks have thick, powerful legs with a diameter averaging around 2.5 cm. Females’ legs are a little more slender at around 2 cm diameter.
Robust leg muscles allow the goshawk to exert tremendous grip strength on prey. Combined leg power and body bulk help the male overpower even squirmy rabbits and large bird prey.
The thick scaling on goshawk legs also protects them when crashing through vegetation in pursuit of prey. Males tend to crash through more aggressively thanks to their greater body mass.
Difference Between Males and Females
To summarize the size differences:
- Males have a 20% larger wingspan than females.
- Male body length is around 15% more than females.
- Males weigh 25-50% more than females.
- The male’s tail is around 10% longer.
- Male legs are around 20% thicker in diameter.
In all physical dimensions, the male Northern Goshawk averages between 10-50% larger in size than the female. This marked reverse sexual dimorphism gives the male substantial physical advantages.
Why Are Male Goshawks Bigger?
There are several evolutionary reasons why male goshawks are considerably larger than females:
- Bigger size aids males in defending nesting territories from intruders.
- Greater bulk and power helps males capture prey to feed females and the young.
- Larger wingspans improve male flight performance for territorial displays.
- Outcompeting other males to secure the best territories and mates.
- Intimidating potential rivals for breeding rights.
In summary, the male’s larger size helps him succeed in securing the best breeding opportunities to pass on his genes. His bulk and power also help provide food for his mate and offspring.
Male Size Compared to Other Birds of Prey
How does the male Northern Goshawk’s size compare to other birds of prey?
The Northern Goshawk is considered a large raptor species alongside others like eagles, buzzards and red-tailed hawks.
In terms of wingspan, the male goshawk is dwarfed by large eagles (over 2 m wingspans) but is larger than mid-sized raptors like buzzards.
The goshawk is heavier than most hawks apart from some buteos like Ferruginous Hawks and Red-tailed Hawks.
Overall, the male Northern Goshawk is one of the largest accipiters but smaller than most eagles and the very largest buteo hawks. The male goshawk is bigger than its close relative, the Cooper’s Hawk.
So it ranks as a large, powerful, mid-sized raptor but doesn’t match the largest eagle species. Its size and strength suit its habitat of dense forests when chasing agile avian prey.
Growth Rate of Males
Male goshawks need over a month to attain full adult dimensions. Here are approximate growth milestones:
- At one month old, males are around two-thirds of adult weight.
- By 45 days, they reach 90% of adult weight.
- Adult weight is attained at around 55 days old.
- Wingspan reaches full adult size at 60-65 days.
- Legs and foot strength mature at around 75 days.
So male goshawk fledglings need around 2 months after hatching before attaining full adult size and power. Their rapid growth aids survival, as bigger size provides advantages in sibling competition and escaping predators.
Changes Through Life Stages
Male goshawks go through some key body changes as they mature:
- As nestlings, covered in white down.
- Fledglings have juvenile plumage lacking adult coloration.
- At one year old, adult feathers start growing in.
- Mature adult plumage achieved by around 18 months old.
- Reaching full body size takes 1-2 years.
- Peak strength and agility from about 3-8 years old.
- As seniors over 12 years old, some decline in hunting prowess.
So goshawks take several years to attain peak size, coloration and hunting abilities as adults. They maintain their faculties through much of adulthood but gradually weaken in old age.
Role of Nutrition
A male goshawk’s size is influenced by nutrition during key growth phases:
- Chicks need high protein from meat to support rapid growth.
- Fledglings require abundant small prey to bulk up.
- Years 1-2: diet shapes adult size and strength.
- Prime adults eat birds up to their own body size.
- Seniors gradually weaken without adequate nutrition.
Male goshawks need a protein-rich, high calorie diet especially in their first years to attain full size. Access to plentiful avian prey enables them to bulk up and strengthen. As seniors they gradually lose muscle mass and power.
Typical Prey Items
Male goshawks are powerful predators taking varied prey:
- Grouse – abundant forest bird up to goshawk’s own size.
- Squirrels – nimble mammals, important prey source.
- Rabbits – challenging prey when available.
- Songbirds – often snatched in flight.
- Doves – plump, swift-flying for fuel.
- Woodpeckers – awkward but nutritious prey.
- Corvids – cunning but picked off when possible.
This combination of protein-rich avian prey and nimble mammals enables the male goshawk to achieve an impressive bulk.
Territory Size
Male goshawks defend large forest territories up to 12 square km (4.6 square miles) in area.
Within these territories, the male goshawk will have favorite hunting perches and plucking posts where he plucks captured prey.
By patrolling and hunting within his territory, the male goshawk is able to find sufficient prey to sustain himself and his mate and offspring.
The extents of his territory are marked by alarm calls and aerial displays to warn off intruders.
Nesting Dimensions
Goshawks do not build their own nests. They nest in old corvid or squirrel nests at the crook of large branches.
Typical goshawk nest dimensions are:
- Nest width: 60-80 cm (2-2.6 ft)
- Nest depth: 30-60 cm (1-2 ft)
- Nest interior diameter: 35-50 cm (1.1-1.6 ft)
- Height above ground: 4-20 m (13-66 ft)
These relatively large nests, situated high up, offer security and can accommodate the female plus up to four chicks.
Conclusion
In summary, male Northern Goshawks are imposing aerial predators. They have a wingspan around 110 cm, body length of 55-65 cm and weight from 0.8-1.6 kg.
Their substantial size aids territorial defense, catching prey, and securing the best breeding opportunities. This is likely why male goshawks outsize females in this species.
A rich diet enables goshawks to attain their full grown size within two years, and they maintain peak hunting abilities until late in life. The male’s size and power allow it to dominate forest habitats and flourish as a breeding raptor.