Bald eagles, the national symbol of the United States, are magnificent birds known for their piercing stare and sharp talons. They also have a reputation for being able to carry heavy loads, but how much weight can a bald eagle carry? Read on to find out more.
Bald Eagle Stats
The beautiful bald eagle is one of the largest eagle species in the world. It has a wingspan of 6-8 feet (2-2.4m), a body weight of up to 6.4kg (14lbs) and a bite force of 400lbs per square inch (aka psi). To put this into perspective, most dog breeds have a bite force of 200-250psi.
Fun fact: A bald eagle’s grip is 10 times stronger than the average adult human!
Their grip is comparable to their bite force, with scientists recording an average grip of 400psi or more. They need a strong grip as they hunt by swooping and grabbing their prey from above.
The bald eagle is able to carry large fish and small mammals up to 30% of its body weight. This means they can carry prey as heavy as 1.92 kg (4.2lbs). Interestingly, they cannot catch fish from deep water as the water pressure prevents them from opening their talons quickly.
Females are larger than males, but there is no visible difference between the two sexes. Bald eagles have white feathered heads, dark brown feathers across the body and legs, white tails and the eyes, beak and feet are yellow. Juveniles have a mottled brown and white plumage.
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Habitat
Bald eagles are actually sea eagles, but most nesting pairs are found inland around lakes, rivers, estuaries and marshes. There were once thousands of breeding pairs across contiguous US, Canada and Alaska.
Most of the remaining breeding pairs are now found in Canada and Alaska, however, there are still significant populations in the Great Lakes states, around Chesapeake Bay and along the Mississippi river.
When the environment is mild year-round, bald eagles do not migrate. For bald eagles living in regions with cold, snowy winters, migration is common between November and March. Migratory birds will travel to warm southern states such as Florida and into Mexico.
The ideal habitat is close to water with a strong fish population, plenty of perching areas and tall trees with thick branches for nest building.
Diet
The majority of a bald eagle’s diet is fish, including salmon, herring and catfish. They will perch on trees above water and swoop down to catch fish as they come to the surface.
Fun fact: Eagles fill their crop with food as a back-up for days when prey is scarce.
Bald eagles are opportunistic feeders and will also eat carrion, such as fish washed up on shorelines or carcasses left by other predators. It is common, especially during the breeding season, to see bald eagles feeding on deer carcasses and road kill.
If the animal is smaller and does not weight as much, bald eagles will try to carry their food away where they can feed safely. Other eagles may try to steal carcasses if food is scarce.
They are also known to hunt other shorebirds, small mammals such as rabbits, mice and voles, crabs, small lizards, newts and frogs.
Breeding
Bald eagles are monogamous, meaning they mate for life. Nests are typically built at the top of tall, old trees with branches that can support the weight of the nest and both eagles. Nests are normally 4-5ft (1.5m) in diameter and a breeding pair often add to their nest each year.
Fun fact: The biggest recorded nest was 9.5ft (2.9m) across, 20ft (6m) deep and weighed almost 6000lbs(2722kg)!
In regions where there are no trees or the trees are not suitable to carry the weight of both bald eagles and the nest, a breeding pair may build their nest on a clifftop or rocky outcrop. Nests are usually built near water sources so that there is a nearby food source.
Eagles reach sexual maturity around 4-5 years old, but may not breed for a year or 2 after. Breeding season varies between northern and southern territories. In the south, females will begin laying eggs in November, but in northern regions egg laying occurs between March and May.
Courtship rituals include dramatic flight displays of swooping, circling and cartwheeling. Pairs may also exchange sticks mid-flight. Even bonded pairs will engage in courtship displays each year. mating is a much calmer affair, typically occurring in the nest or on a branch close to the nest.
The female will lay up to 3 eggs between 5 and 10 days after mating. Eggs are an off-white colour and measure approximately 3 inches (7.6cm) in length. Incubation last around 35 days, with both parents taking turns. While one sits on the egg, the other will hunt for food and protect the nest from predators.
Eagles are fierce in their defence and will chase away other eagles, even grappling mid-flight with their talons. Juveniles will fledge (take their first flight) around 10-12 weeks of age. At this age, they will not grow any larger, but they retain their juvenile plumage for around 3 years.
Threats & Conservation
In the late 1700s, the population of bald eagles in the US and Canada was hundreds of thousands. A steadily decline began due to sport hunting, farmers trapping and killing birds to protect their livestock and later, the use of pesticide DDT.
After the second World War, DDT became a widespread agricultural pesticide. The chemical would leach into the ground and nearby water sources. DDT would then accumulate in the tissues of fish, which the eagles hunt and eat.
DDT causes poor shell formation, so many bald eagles’ eggs never hatched or they would not lay at all. This, combined with hunting caused number to drop to less than 450 pairs.
By the 1960s, the US government had introduced a country-wide ban on DDT use and, coupled with successful reintroduction programs, bald eagle populations began to recover.
In the early 2000s there were an estimated 6300 breeding pairs and the bald eagles was downgraded from ‘endangered’ to ‘threatened’. By 2007 the bald eagle was removed from the list and today’s estimate is a population of approximately 300,000 individuals across the US, Canada and Alaska.
So, if you ever wonder how much weight a bald eagle can carry, estimate its body weight and you will now know it is 30% of that.
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