Verreaux's eagle-owl

Verreaux's eagle-owl (Ketupa lactea), also commonly known as the milky eagle owl or giant eagle owl, holds the distinction of being the largest owl species native to Africa. This imposing bird is primarily found in dry, wooded savannas across sub-Saharan Africa, where it is a resident species. Its appearance is marked by a generally grey plumage, but it is most famously and uniquely distinguished by its bright pink eyelids, a feature not shared by any other owl species.

Physical Characteristics and Size

Despite the common name 'giant eagle-owl,' Verreaux's eagle-owl is not the largest owl globally but is indeed the largest in Africa and the largest owl found in the tropics. It ranks as the fourth heaviest living owl worldwide. Total length typically ranges from 58 to 66 cm (23 to 26 inches). There is significant sexual dimorphism, with females being considerably larger and heavier than males, sometimes by as much as 35%. Wingspans can reach up to nearly 164 cm (5 ft 5 in) in females. Its plumage is a relatively uniform pale grey, with fine brownish vermiculations underneath and white spots on the back. The facial disc is paler, bordered by black, and its eyes are dark brown. The ear-tufts are present but are described as blunter and smaller compared to those of other African eagle-owls.

Diet and Hunting Behavior

Verreaux's eagle-owl is a highly opportunistic predator, a trait common among its genus. Its diet is remarkably diverse, with mammals constituting just over half of its known prey. However, it also hunts birds and insects in significant numbers, depending on local availability. Studies have identified over 100 prey species, ranging from insects weighing less than 5 grams to ungulates weighing at least 10 kg (22 lbs). Hedgehogs are a particular favorite, with the owl being one of the few predators that routinely tackles these spiny mammals. Hunting typically occurs at night, with the owl often perching and then gliding down onto its unsuspecting prey. It is also capable of hunting on the wing and ambushing prey in dense foliage or shallow water.

Habitat and Distribution

This species inhabits a vast area of sub-Saharan Africa, though it avoids the deep rainforests. Its preferred habitat is savanna with scattered trees and thorny vegetation, often in rather dry or semi-arid regions. They require trees for nesting and hunting, thus avoiding completely open or true desert environments. Riverine forests and small, semi-open woodlands are also utilized. Verreaux's eagle-owls can be found from sea level up to elevations around 3,000 meters (9,800 ft), though they are less common in mountainous regions. While historically absent from the Kalahari Desert, the introduction of invasive trees and irrigation has led to their sporadic presence there.

Vocalizations and Behavior

The call of the Verreaux's eagle-owl is exceptionally deep, ranking among the deepest bird calls in the world. The male's song is a distinctive 'gwok, gwok, gwonk-gwokwokwok gwokwokwok gwonk,' which can be confused with the sound of a leopard. The female's call is similar but higher pitched. Alarm calls are typically a sonorous 'whok' or 'hook.' These owls are nocturnal, roosting in trees during the day, often on large, shaded branches. They are territorial, with breeding pairs defending large areas. Family groups, sometimes including young from previous years, have been observed roosting together.

Conservation Status

Verreaux's eagle-owl is classified as 'Least Concern' by the IUCN. This status reflects its wide distribution across sub-Saharan Africa and its demonstrated adaptability to human-induced habitat changes and variations in prey populations. Despite its large size and territorial nature, it maintains a healthy population across its range.