Shelley's Eagle-Owl

This dark eagle-owl is among the largest owls in the world and by far the largest eagle-owl found in the African rainforests. The total length of the species is 53 to 61 cm (21 to 24 in). The wing chord measured from 420 to 492 mm (16.5 to 19.4 in), its tail is about 233 to 266 mm (9.2 to 10.5 in) , the tarsus at 76 to 84 mm (3.0 to 3.3 in) and the total bill at 56 to 62 mm (2.2 to 2.4 in). A single male was reported to have weighed 1,257 g (2.8 lb), with females presumably attaining rather higher weights. Going on standard measurements, the Shelley's eagle-owl would appear to be even larger than the aforementioned total length and body mass suggest. In the key aspects of wing and tarsal lengths, Shelley's eagle-owl appears to be broadly similar in size to the Verreaux's eagle-owl, which is usually considered to be Africa's largest owl species, and it may be one of the largest tropical owls in the world. The bill of the Shelley's eagle-owl is proportionally massive and seemingly the second longest of any living owl behind only the Blakiston's fish owl. Its upperparts are dark sooty black-brown overlaid with light barring. The underparts are whitish with heavy dark barring. Lighter and darker morphs are known. The light morphs have an off-white to pale tawny facial disc, with a prominent rim marked with a blackish-brown border. …

This species is found in Central and Western Africa. It has been found in widely scattered locations, perhaps isolated by habitat destruction. One isolated population is thought to live in a small area of inland Liberia, as well as adjacent extreme southeast Sierra Leone, western Ivory Coast and the southeastern tips of Guinea. An isolated population may persist in southern Ghana. The largest probable population is in southern Cameroon (also possibly extreme southern Nigeria), much of the non-coastal parts of Equatorial Guinea and Gabon, the Republic of the Congo and a large swath of northern Democratic Republic of the Congo, perhaps reaching Uganda. It is a resident of lowland, tropical rainforests and has never been collected outside densely forested and old growth areas.

The Shelley's eagle-owl is a nocturnal bird which spends its days roosting in dense foliage, reportedly often at quite low levels in trees. Few living wild specimens have ever been studied and until 2021 the species was never known to have been photographed in the wild. Persistent singing by the species has been heard in March, at least in Liberia. The typical call is a loud, wailing kooouw (very different and much higher pitched from the typical calls of other eagle-owls of large size, which often call with sonorous hoots) given at intervals of several seconds. A loud peeping sound has also been reported, possibly in times of stress. Heard far more often than it is seen, Shelley's eagle-owls are said to vocalize most persistently at or just before dawn and around dusk.

Breeding. Details of the species' breeding habits are not generally known and only incidental observations have been made. In Democratic Republic of the Congo various stages of development were witnessed in different months: recently fledged young in April, a large nestling in September and a juvenile in mesoptile plumage in early November. Additionally, an adult was seen roosting with a probable juvenile in December in the Cameroon.

Feeding. The powerful talons and feet of the species suggest that its preferred prey consists of medium-sized mammals and large birds. …