The Northern Harrier (Circus hudsonius) is a medium-sized bird of prey found across North America. Also known as the “hen harrier” or “marsh hawk”, it is a slender raptor with long, broad wings and a small head. Northern Harriers are notable for their acrobatic flight displays, patrolling low over open habitats in search of small mammals, birds, reptiles and amphibians to prey on.
One of the most frequently asked questions about Northern Harriers relates to their size – specifically, how big do they grow? This article will provide a comprehensive overview of the size of Northern Harriers, looking at their wingspan, body length, weight ranges and how their size compares to other birds of prey. Read on to learn all about the dimensions of these fascinating raptors!
Wingspan
The wingspan is the distance between the tip of one wing to the tip of the other wing when fully extended. This measurement gives a good indication of the size of a bird in flight.
An adult male Northern Harrier has a wingspan ranging from 40 to 52 inches (101 to 132 centimeters). Females are noticeably larger with a wingspan of 44 to 54 inches (112 to 137 cm). This places the Northern Harrier on the larger end of medium-sized raptors, with a wingspan slightly smaller than many Buteo hawks like Red-tailed Hawks.
The long, slender wings of the Northern Harrier allow it to fly with incredible agility and maneuverability as it hunts. The wings enable the harrier to suddenly change direction and fly very low to the ground as it pursues prey through thick vegetation.
Body Length
Body length is another useful measure of a bird’s overall size. This is the length of the bird’s body from the tip of its beak to the end of its tail feathers.
Male Northern Harriers have an average body length of 18-20 inches (46-51 cm). Females are noticeably larger at 20-24 inches (51-61 cm) long. This puts the Northern Harrier as a medium-large sized raptor, being longer than falcons but smaller than most eagles or buteos.
The slender body and long tail of the Northern Harrier allow it to twist and turn through dense vegetation while hunting. The body length also gives ample space for carrying prey items securely in their talons.
Weight
The weight of a raptor provides further insight into its size and strength. Male Northern Harriers are lightweights, weighing just 24 to 48 ounces (680 to 1,350 grams). In comparison, females are much heavier at 38 to 66 ounces (1,080 to 1,870 grams).
This moderate weight allows the Northern Harrier to fly effortlessly for long periods while hunting, but does limit the size of prey they can strike and carry. Larger hawks and eagles can take down bigger prey with their greater body mass and grip strength.
By bulking up with reserves before migration, Northern Harriers can weigh up to 100 oz (2,835 g). Even at their heaviest, they are still a relatively slender, lightweight raptor compared to buteos, eagles and owls.
Wingspan Comparisons
Comparing the Northern Harrier’s wingspan to other raptors gives a better sense of their relative sizes:
– Sharp-shinned Hawk – 22-29 inches wingspan, much smaller
– Cooper’s Hawk – 29-37 inches, smaller
– Red-tailed Hawk – 43-56 inches, similar size
– Red-shouldered Hawk – 38-42 inches, slightly smaller
– Broad-winged Hawk – 34-44 inches, similar size
– Swainson’s Hawk – 47-54 inches, larger
– Rough-legged Hawk – 49-57 inches, larger
– Ferruginous Hawk – 50-60 inches, larger
– Golden Eagle – 66-84 inches, much larger
So while Northern Harriers are considered a medium-sized raptor, they are on the small end of that spectrum, with most buteos and all eagles substantially outweighing them. The extra-long wingspan of the Northern Harrier allows it to hunt in more open environments than similarly-sized forest hawks.
Length Comparisons
The body length of an adult Northern Harrier compared to other raptors:
– American Kestrel – 9-12 inches, much smaller
– Merlin – 11-13 inches, quite a bit smaller
– Peregrine Falcon – 15-21 inches, smaller
– Red-tailed Hawk – 17-25 inches, slightly larger
– Red-shouldered Hawk – 16-23 inches, slightly smaller
– Harris’s Hawk – 17-23 inches, similar length
– Grey Hawk – 15-22 inches, similar length
– Zone-tailed Hawk – 20-26 inches, larger
– Golden Eagle – 27-33 inches, substantially larger
Again this highlights that the Northern Harrier is a medium-small sized raptor in terms of length. Their long wings compensate for their petite bodies. The female harrier’s greater length allows her to tackle larger prey.
Weight Comparisons
Looking at the weight ranges of some common North American raptors shows how light the Northern Harrier is relative to its wingspan:
– American Kestrel – 3-6 oz, tiny compared to a harrier
– Merlin – 180-240 grams, 5-8 times lighter
– Peregrine Falcon – 21-51 oz, about half the weight
– Red-tailed Hawk – 24-51 oz, same ballpark as a male harrier but females much heavier
– Red-shouldered Hawk – 21-35 oz, slightly lighter than a male harrier
– Broad-winged Hawk – 13-34 oz, mostly lighter than harriers
– Swainson’s Hawk – 33-54 oz, heavier than a male but similar to a female
– Ferruginous Hawk – 48-70 oz, noticeably heavier than harriers
– Bald Eagle – 73-112 oz, much heavier than even a female harrier
The light weight of the Northern Harrier is an adaptation for ground hunting in wide open spaces. Harriers rely on speed and aerial agility to overwhelm prey rather than brute strength.
Conclusions
So in summary, the Northern Harrier is considered a medium-sized raptor but comes in on the petite end of that spectrum due to its slender, lightweight build. It has a wingspan in the 40-54 inch range, body length of 18-24 inches and weighs just 24-66 ounces.
While they have the long wing proportions for hunting over open terrain, they do not have the heft and bulk of many buteo hawks or large eagles. But the harrier’s more compact size allows it to hunt with great aerial skill and maneuvers.
The moderate measurements of the Northern Harrier reflect its evolution as a swift, agile hunter that relies on swiftness and element of surprise rather than sheer strength. So next time you see a Northern Harrier patrolling over a field, take note of its size and try picturing just how nimble this raptor must be in flight to catch its prey!
Frequently Asked Questions
Here are answers to some common questions about the size of Northern Harriers:
Why are female Northern Harriers larger than males?
This size difference is an example of reverse sexual dimorphism, where females are larger than males. The extra size of female harriers allows them to hunt larger prey to provide for their offspring. Males are smaller and more agile to better chase down prey.
How do Northern Harrier sizes vary across their range?
There are slight regional size variations in harriers, with the largest birds found at the extreme northern parts of their range in Canada. Southern breeding birds average a bit smaller. Migratory populations also bulk up seasonally before long migrations.
How does the harrier compare to other hawks like sharp-shinned and Cooper’s hawks?
The Northern Harrier has a moderately larger wingspan but much lighter build than these two forest-dwelling accipiters. Harriers hunt more open areas and take different prey than the forest hawks.
Why is the harrier designed the way it is?
The combination of large wings, slender body and light weight allows the agile flight needed to hunt in open marshes and fields. Their proportions are specialized for their habitat and style of hunting.
How much bigger is an eagle than a harrier?
Eagles like the bald eagle are substantially bulkier and heavier than the light Northern Harrier. An eagle’s wingspan is 20-40% larger than a harrier’s, with at least double the body mass.
Northern Harrier Size Facts
– Wingspan of 40-54 inches
– Body length of 18-24 inches
– Weigh 24-66 ounces
– Females average 10-20% larger than males
– Medium-sized in length but lightweight build
– Long, broad wings for hunting open areas
– Much smaller and lighter than eagles or buteo hawks
– Well-designed for fast, agile aerial hunting
Measuring a Northern Harrier
It’s tricky for the average person to get exact measurements of a wild Northern Harrier. But with some simple observation, you can still get a good sense of their size:
– Note whether it is smaller and more slender than a nearby Red-tailed Hawk
– See if the wings seem disproportionately long compared to the body size
– Watch it fly and look for highly agile maneuvers indicating a lightweight build
– If seen well on the ground, see if the body seems long and slender
– Note whether the bird seems smaller or slimmer than expected
Observing the agility and proportions of a Northern Harrier can provide clues about its size even without measurements. Over time you will develop an eye for the flight style and dimensions of this graceful raptor.
Significance of Size
The moderate size and lightweight build of the Northern Harrier is perfectly adapted to its habitat and method of hunting. Size impacts a raptor’s diet, flight capabilities and more:
Diet
The harrier’s medium wingspan allows it to take moderately sized prey like small rodents, birds and reptiles. Their light build prevents them from tackling larger prey.
Flight and Hunting
Long, broad wings provide lift and control for low, hovering flight over open areas. Their nimble flight permits sudden aerial maneuvers to grab prey.
Migration
A compact body size reduces drag and energy costs for migratory populations. Bulk weight gain before migration provides reserves.
Reproduction
Females are larger to be able to take bigger prey to feed hungry nestlings. Smaller males can better chase prey and guard territories.
Every aspect of the Northern Harrier’s specialized size and proportions provide advantages for life in open country as an aerial hunter.
Conclusion
In summary, the Northern Harrier is considered a medium-sized raptor but is petite for the group, with a slender build and light weight. Average wingspans range from 40-54 inches, body lengths 18-24 inches and weight just 24-66 ounces. Their proportions allow outstanding aerial agility and suit the harrier’s habitat and hunting style perfectly. Hopefully this overview gives you a better understanding of the size of these elegant open country raptors!
