The World's Heaviest Flying Bird Weighs As Much As 300 Tennis Balls

Ahh the bird world, full of incredibly beautiful species that fly, swim , and even just walk (looking at you kiwis ) across a vast array of Earth’s diverse habitats. While some species enter the record books for their amazing feats of endurance, soaring for days without touching the ground, we take a closer look at the heaviest bird to grace our skies.

Meet the kori bustard ( Ardeotis kori). The males weigh between 11-19 kilograms (24-42 pounds) with a wingspan of up to 2.75 meters (9 feet). Sexually dimorphic, the females are roughly half of that size, explains the Smithsonian National Zoo .

The Guinness Book Of Records states that the largest confirmed specimen weighed 18.14 kilograms (40 pounds). The bird was shot in South Africa and was documented in 1936.

These birds live in two distinct ranges in South and East Africa and spend most of their time on the ground foraging. Their diet includes a wide range from insects, reptiles, and small rodents to seeds, berries, and roots. The International Union for Conservation of Nature lists the kori bustard as Near Threatened and describes them as “largely sedentary, but does undertake local movements”.

The second heaviest flying bird is also a species of bustard – the great bustard ( Otis tarda ). They weigh only slightly less than the kori bustard at around a maximum of 6–18 kilograms (13-39 pounds). Unlike the kori bustard, which does not migrate and rarely flies very far at one time, great bustards were revealed to have a migration round trip of over 4,000 kilometers (roughly 2,485 miles) between their breeding grounds in Mongolia and their winters in China.

Great bustards, like the kori bustard, show a great deal of sexual dimorphism and might have the largest size difference between males and females of any bird species. The males weigh up to four times the weight of the females.

In complete contrast, the world’s heaviest bird that can’t fly is the southern African subspecies of the common ostrich. The South African ostrich ( Struthio camelus australis ) can reportedly weigh 156 kilograms (343 pounds).

Of course, with all this talk of birds, we’ve forgotten the heaviest flying mammals, the flying foxes , which weigh a comparatively measly 0.5-1.0 kilograms (1-2.2 pounds) depending on the exact species. There maybe be hope though for a larger flying mammal yet as new research has revealed that hippos are in fact taking to the skies.