Hawk

Quick Take

• The sexes of most animals follow a familiar size pattern, but hawks break it in a way most people never expect. Size differences explained →
• Hawk chicks face a threat inside the nest that has nothing to do with predators. Chick development details →
• Hawks and falcons look similar and hunt the same way, yet science draws a hard line between them. The reason traces back over 100 million years. Hawks vs. falcons origins →
• A hawk's vision sounds impressive on paper, but the actual gap between their eyesight and ours is far wider than most people assume. Hawk vision facts →

A hawk is not one specific bird of prey; it’s a general name used to describe 270 different types of diurnal carnivorous birds. These birds are primarily classified under the order Accipitriformes, while true falcons belong to the separate order Falconiformes. The term ‘raptors’ is commonly used for all birds of prey, including hawks and buzzards.

While each species of hawk has its own unique features, they all have many characteristics in common, like sharp eyesight, hooked beaks, and sharp talons. However, they vary significantly in size.

Hawks are skilled predators that use their keen eyesight and agility to capture prey, often swooping down quickly to catch animals on the ground or in vegetation.

Eight Hawk Facts

• There are 270 species of hawks, 25 of which are located in the USA.
• The biggest hawk in North America is the ferruginous hawk.
• The most populous hawk species in the USA is the red-tailed hawk.
• Red-tailed hawks mate for life.
• The only place in the world where hawks don’t exist is Antarctica.
• Females are 25 to 30% bigger than the males.
• A group of hawks is referred to as a kettle.
• Hawks can see 5 times better than humans.

Classification and Scientific Name

Hawks are diurnal birds of prey that hunt during the day. They are primarily classified in the family Accipitridae, within the order Accipitriformes. There are a few subfamilies, including:

• Accipitrinae: These are “true hawks” (e.g., genus Accipiter or Astur, which include Cooper’s hawks and sharp-shinned hawks).
• Buteoninae: These are broad-winged soaring hawks (e.g., genus Buteo, which includes the red-tailed hawk).
• Other Groups: These include harriers (Circinae), kites (Milvinae), and other raptors.

There are 270 different species of hawk, including the following:

• Cooper’s hawk (Accipiter cooperii)
• Harris Hawk (Parabuteo unicinctus)
• Sharp-shinned hawk (Accipiter striatus)
• Common buzzard (Buteo buteo)
• Honey-buzzard (Pernis apivorus)
• Harris’s hawk (Parabuteo unicinctus)

Appearance

Hawks vary in size, with the lightest species being the roadside hawk, which weighs only 9.5 ounces. Their length can stretch 12 to 28 inches, while hawks’ wingspans range from 26 to 63 inches. For example, the white-rumped hawk’s and Ridgway’s hawk’s wingspans measure 30 inches, and their length averages 14 inches.

While the ferruginous hawk is the largest species in the USA, Asia’s upland buzzard is the biggest overall. They are 26 inches long with a wingspan of 60 inches. However, the ferruginous hawk weighs the same and has bigger foot measurements and bill size. Males are smaller, only weighing 2.5 pounds, while females average  4.4 pounds when fully grown.

Evolution and Origins

Hawks developed in Africa and falcons in South America independently after the division of Gondwana into separate continents around 100 million years ago. It appears that each region independently evolved a diurnal raptor suited to its habitat.

Theropods were a group of meat-eating dinosaurs from which birds descended. Although birds originated from little theropods rather than gigantic ones like Tyrannosaurus rex, they nonetheless belong to the same group as the dinosaur. The earliest fossilized bird remains date back 150 million years.

The earliest known raptor fossils date from the Eocene Epoch (about 56 to 34 million years ago), and some of the earliest forms may have resembled modern vultures.

Habitat

Hawks dominate the world and thrive in all sorts of climates and environments. The only place on the planet they don’t inhabit is Antarctica. They can survive as long as there is prey to eat and a safe place to nest.

Most hawk species migrate, but a few don’t; generally, a hawk that does not flock does not migrate.

Diet

Most birds of prey are opportunistic hunters and are not picky. They will take a meal wherever they can find it, but typically, their food of choice is rodents. Unfortunately for hawks, most rodents are active at night, so most of their diet consists of diurnal gerbils, squirrels, voles, and chipmunks.

Other prey includes:

• Shrews
• Moles
• Pikas
• Weasels
• Rabbits
• Hares
• Marmots
• Small to medium-sized birds
• Snakes
• Lizards
• Frogs
• Salamanders
• Fish
• Various invertebrates

Predators and Threats

Fully-grown hawks generally have very few predators. Their razor-sharp beaks and talons are a great deterrent, and their ability to fly helps them escape larger animals.

Many hawks are among the top predators in their environments, though they can still fall prey to larger raptors or mammals.

Sadly, hawk eggs and chicks are often targets of owls, larger birds of prey, crows, raccoons, porcupines, ravens, and snakes. As a result, mothers must keep their eggs and babies hidden until they are old enough to protect themselves.

Reproduction, Babies, and Lifespan

Like most bird species, hawks build nests from sticks, leaves, and other materials. For hawks who nest in trees, selecting the perfect tree requires careful consideration. Hawks need to ensure their tree is large enough or well-hidden to be inaccessible to climbing predators.

Most species will mate for life or at least for several years; this includes migratory species where pairs separate for the winter.

Hawks can lay between 2 and 7 eggs at a time; most of the time, the female will incubate the eggs, and the male will go out and hunt.

When the eggs hatch, the chicks rely solely on their parents to provide safety and food. Their survival depends on the location of the nest, nearby predators, and whether there is human activity such as logging or hunting in the area.

The eggs do not all hatch at once; there are usually intervals of a day or two, which means the older, stronger chicks have a better chance of survival as they can fight for their food, and sometimes kill their smaller siblings by aggressively handling them.

The female spends most of the time with the chicks while the male is out hunting. However, males do brood the chicks from time to time.

When the chicks reach their fledgling stage, the mother takes over the majority of the hunting. After a couple of weeks, the fledglings realize their parents are indifferent to feeding them and sometimes even hostile, signaling that it’s time to leave the nest.

The fledglings initially stay close to their old nest, usually within several miles. Then, after one or two years of being on their own, they start to court mates and create their own families.

Hawks generally live up to 12 years; however, in captivity, they can live much longer.

Population

Because “hawk” is a term used for 270 species, it’s hard to accurately determine their population size. Some hawks, like the red-tailed hawk, have huge numbers, while other species, like the Ridgway’s hawk, are critically endangered.

For example, there are around 1,960,000 nesting red-tailed hawks in the world, and 90% of their population call North America home.