Eagles are iconic, formidable, and impressively large birds of prey. Determining which eagles are the biggest in the world requires an examination of mass, length, and wingspan. The lens needs to be directed at all continents (save for Antarctica) and even back in time. It is also important to consider the collective averages versus the greatest individual dimensions ever recorded (in the wild or captivity). As you might suspect, overlapping bell curves create significant gray areas. The first entry on this list is clearly the apex eagle, but beyond that, some interpretation is required.
Haast's Eagle (Harpagornis moorei)
The largest documented species of eagle, by any metric, was the Haast's eagle. The giant New Zealand predator went extinct about 500 - 600 years ago, but its dimensions and characteristics have been surmised by examining skeletal remains and incorporating Maori oral traditions. It is estimated that the Haast's eagle weighed in at a whopping 39 pounds, with a body length of 35 - 55 inches and a maximum wingspan of about 9.8 feet. It used its colossal strength to hunt moa (nine species of large, flightless birds). Overhunting of moa by humans led not only to their extinction but wiped out the necessary food source to sustain the Haast's eagle population.
Steller's Sea Eagle (Haliaeetus pelagicus)
Steller's sea eagle (named after German naturalist Georg Wilhelm Steller) is one of the largest living eagles. On average, it weighs 10.8 - 20.9 pounds, with a body length of 33.5 - 41.3 inches and a wingspan of 6.2 - 8.2 feet. Though there are counter examples of individual eagles from other species, Steller's sea eagle is, on average, the heaviest. They sustain their notable girth on a diet of fish and water birds. The population (which can be found throughout East Asia) is decreasing and is listed as "Vulnerable" (VU) on the International Union for Conservation of Nature's Red List.
Golden Eagle (Aquila chrysaetos)
The golden eagle is not only large but fast! In fact, it is second only to the peregrine falcon in terms of raw speed. Only these two species can reach the 200 mph threshold while diving for prey (mostly consisting of small mammals, as well as fish, birds, and reptiles). While soaring, the golden eagle can reach speeds of 30 mph. What is particularly impressive about these statistics is that they are logged by such a sizable creature. With an average wingspan of 7.2 feet, a height of about 33.1 inches, and weighing in at 13.5 pounds, the golden eagle is one of the largest birds in North America. The largest individual ever caught in the wild was a 17-pound female. However, in captivity, one golden eagle grew to a hefty 27 pounds, with a wingspan of 9.25 feet.
Harpy Eagle (Harpia harpyja)
The Harpy eagle is the largest and most dominant raptor in the Amazon rainforest and is not far removed from the biggest in the world. This carnivorous predator has a wingspan of 5.75 - 7.3 feet, the largest talons of any living eagle, the ability to lift prey equal to its body weight (9 - 20 pounds), and it can reach a top speed of 50 miles per hour. It uses these tools to hunt a wide array of animals, including sloths, monkeys, porcupines, squirrels, anteaters, iguanas, snakes, other birds (and their eggs), such as the macaw, and many more. Harpy eagles have a vast territory spanning from Mexico down to Argentina, but their numbers are on the decline, and they are listed as "Near Threatened" (NT).
Bald Eagle (Haliaeetus leucocephalus)
Everything is bigger in America. Therefore, lovely as they may be, no finch or sparrow would suffice for the national symbol of freedom - only the bald eagle can manage that. This patriotic beauty stands proudly at 34 - 43 inches, with a 6 - 8 feet wingspan, and weighs in at 6.5 - 14 pounds. Ironically, the bald eagle was nearly wiped out in the United States. They were previously hunted en masse, and widespread use of chemical pesticides (DDT) led to reproductive issues. Thankfully, the bald eagle represents a victory for animal conservation. In 1972, DDT was restricted, and the population was boosted through reintroduction programs. Since then, the bald eagle has been upgraded from endangered to "Least Concern" (LC), and the population is still increasing.
Australian Wedge-Tailed Eagle (Aquila audax)
The largest bird of prey down-under is the Australian wedge-tailed eagle. It ranges from 34.3 - 41.3 inches in length, with a wingspan of about 7.5 feet, and females weigh in at 9.3 - 11.7 pounds, while males weigh 7 - 8.8 pounds. Though ominous-looking creatures, the Australian wedge-tailed eagle opts to eat mostly carrion, though they are more than capable of hunting live prey. For the latter approach, they prefer rabbits, but in groups, they can kill animals as big as lambs and adult kangaroos. This species can be found throughout mainland Australia, Tasmania, and Southern New Guinea.
Martial Eagle (Polemaetus bellicosus)
The Martial eagle, or African Martial eagle, is the largest eagle in Africa (though the African crowned eagle and Verreaux's eagle are other impressive specimens on this continent). The Martial eagle weighs between 6.6 - 13.2 pounds, has a body length of 30.7 - 37.8 inches, and a wingspan of 6.2 - 8.5 feet. These captivating birds live throughout most of sub-Saharan Africa, particularly in open woods, woodland edges, wooded savannah, and thornbush habitats. They hunt during the day and spend a large portion of their time high in the air. They can spot their prey, ranging from small antelopes, monkeys, and domestic animals, to even venomous snakes and wild cats from miles away. Their population is declining, and the Martial eagle is currently listed as "Vulnerable."
White-Tailed Eagle (Haliaeetus albicilla)
The white-tailed eagle, also known as the white-tailed sea eagle, Ern (Erne), gray sea eagle, or Eurasian sea eagle, is Europe's largest eagle and one of Asia's largest. The white-tailed eagle has an average weight of 6.6 - 15.4 pounds, a length of 26 - 37 inches, and a wingspan of 5.9 - 8.2 feet. They are generally found in Northern Europe and Asia, breeding as far West as Greenland and as far East as Hokkaido, Japan. They tend to keep close to water, and in the winter, some flock to coastal spots in the South. The white-tailed eagles are diurnal and spend an admirable amount of time patiently perched on trees or crags. That is, until it is time to catch fish, scavenge carrion, or defend their territory.
These are just some of the most spectacular species of eagles found throughout the world. Each is a finely tuned predator that utilizes size to its full extent. Though dominantly positioned in the food chain, eagles are still impacted by environmental changes, relying on steady food sources free of pollutants to sustain their impressive physiques and reproductive capabilities. Haast's eagle was lost, and the bald eagle nearly followed suit, but trends seem to be improving in many cases for these large and magnificent animals.