Palm-nut Vulture

BirdAfrica

Jul 8

Written By Alexander Julius Jensen

Gypohierax angolensis

The palm-nut vulture is unusual among vultures, in that about 70% of its diet is vegetarian — mostly consisting of palm nut fruits. It was once called the ‘vulturine fish eagle’, because of its eagle-like appearance and the way in which it hunts; swooping to the water's surface to grab fish.

A Rüppells vulture (*Gyps rueppelli*) and white-backed vultures (*Gyps africanus*) feeding on a carcass — both species are critically endangered.

Rapacious Raptors

What comes to mind when you think of an African vulture? You're likely picturing a large bird with a bare serpentine neck and a featherless head. It's probably feasting on a carcass alongside a mob of other scavengers; ripping tendons and entrails, its naked head dripping with blood and gore. These are the white-backed, Cape, and Rüppell's vultures — vital, although unsavoury, “eco-janitors" of the savannah, preventing the spread of diseases by clearing up to 70% of their ecosystem's carrion.¹ The majority of vulture species — both in the Old World and the New — mostly dine on dead stuff, but not all vultures are bloody hypercarnivores.

“Vegetarian” Vulture

A palm-nut vulture feasting on a palm nut fruit — holding it down with its talons and tearing at it with its beak.

The palm-nut vulture is utterly unique among its kind. While most vultures pluck eyeballs from sockets, the palm-nut vulture plucks ripe fruits from trees. Its favourite comes from palm oil trees — either from the African oil palm, the principal source of palm oil in Africa, or palms of the Raffia variety, which are also a source of fibres and wine. The African oil palm produces small, oblong, orange-red fruits, which grow together in clusters of several hundreds. They smell like violets, with a nutty undertone, and taste like mildly sweet olives with an oily, fibrous texture and have an oil-rich white kernel inside the flesh. The fruits of Raffia palms, on the other hand, are covered in glossy golden-brown scales, like small dragon eggs, and are only consumed by humans when boiled.

Named after these fruits, it's unsurprising then that much of the palm-nut vulture's food comes from oil palms. The vulture strips palm nuts of their fibrous brown husks — which it also eats — and then proceeds to devour the rich oily fruits. While this is the base of its diet, it also eats sweet wild dates, and occasionally grains and seeds. All said, around 70% of its diet consists of plant stuff — up to 90% in the case of juveniles — making it the only primarily vegetarian vulture.

‘Vulturine Fish Eagle’

The remainder of its diet — around 30% — is more expected of a raptor. Fish, crabs, molluscs, snakes, small mammals, and bird nestlings; the palm-nut vulture's carnivorous palette is extensive. One thing it scarcely eats, however, is carrion, as it prefers to hunt rather than scavenge from the already dead. In fact, it was once known as the ‘vulturine fish eagle’ for the way in which it hunts fish. Like a fish-eagle, it swoops low over the water, watching with keen eyes for fish close to the surface. It extends its legs forward, unfurling its scaly feet, each armed with four large talons, and plunges them into the water to skewer its unsuspecting prey, before lifting it out and carrying it away — all on the wing.

A juvenile palm-nut vulture on the left and a steppe eagle (*Aquila nipalensis*) on the right — to the undiscerning eye, one can be mistaken for the other.

The palm-nut vulture doesn't just hunt like an eagle, it also looks like one. As a juvenile, its plumage is a mottled brown and, from below, it could almost be mistaken for a golden eagle — or, more accurately given its Sub-Saharan range, a Wahlberg's or steppe eagle. As an adult, it's not particularly large — with a wingspan of about 1.5 metres (5 ft) — but it is quite unmistakable. Its plumage is monochrome. Its wings are broad in flight, with each of its primary wing feathers individually visible, like outstretched white fingers dipped in ink. Its tail is short and wide; mostly black with a white tip. Its head is feathered white, but its face is a bare pinkish-red. Its eyes are large and golden, and its beak is curved and pale — bulky, with a sharp-tipped upper mandible, perhaps used for stripping husks and scales from palm fruits.

The palm-nut vulture looks unusually eagle-like — indeed, it is in the same family (Accipitridae).

The palm-nut vulture's aquiline resemblance is obvious; a reminder that vultures belong in the same family as eagles. The Accipitridae family contains upwards of 230 species of eagles, hawks, harriers, kites, and vultures of the Old World. The palm-nut vulture is the sole species in its genus (Gypohierax), but it belongs to a sub-family (Gypaetinae) of equally odd vultures. These include the egg-cracking Egyptian vulture ² and the bone-breaking bearded vulture ³. The latter, also known as the lammergeier, looks especially eagle-like. Also in the sub-family, are two grey-bodied, long-legged African harrier-hawks (both in the genus Polyboroides). One is found throughout Sub-Saharan Africa, while the other is a Madagascar endemic. And so, the palm-nut vulture is more closely related to these strange raptors, than the long-naked-necked vultures of the African plains.

Committees & Kettles

The palm-nut vulture ranges widely throughout Central Africa, from the west to the east coast, and even down to the continent's southern edge. Naturally, it lives in areas where oil palms are abundant. These trees usually line the edges of tropical forests, the coasts of lakes and rivers, and along the seashore — occasionally, the vultures venture into drier areas, where plantations mean abundant palm fruits. And when the food is abundant, the vultures gather in large numbers; seen perching in trees or waddling around near the water's edge (a group of grounded vultures is called a "committee"). Although palm-nut vultures do not soar as frequently as their cousins on the savannah — who use hot thermals of air to rise and spiral through the sky for up to six hours without a single wing flap — they do enact elaborate and elegant aerial performances during their breeding season; a palm-nut vulture couple will roll and dive through the air, putting on a show that's rarely matched by any other vulture (a group of vultures in flight, oddly, is called a "kettle"). Usually silent birds, palm-nut vultures are known to quietly growl and shriek during their passionate courtship displays.

¹ The byproduct of a vulture's dietary preferences — the cleaning up of carcasses — is hugely beneficial to people. Without vultures, bodies would take three to four times longer to decompose — spreading more contagions. In India, where vulture populations have dropped 99%, the occurrence of rabies and feral dogs has greatly increased.

In terms of benefit to the vulture, its putrid diet, and the biological quirks that enable such eating, can be used for defence and, surprisingly, hygiene. One technique that vultures use to discourage a threat is to vomit on the aggressor. They have some of the strongest stomach acids of all animals, with PH similar to that of battery acid. This also serves to make their excrement a disinfectant; pooping on their own legs to keep them cool and clean.

An egg-cracking Egyptian vulture (*Neophron percnopterus*) on the right and a bone-breaking bearded vulture (*Gypaetus barbatus*) on the left.

² The Egyptian vulture is found throughout southern Europe, western/southern Asia, and Africa during the winter. Its plumage, like the palm-nut vulture's, is black and white, but the Egyptian vulture sports an entirely naked, bright yellow face with a small, skinny beak. Unlike the palm-nut vulture, the Egyptian will happily eat carrion, but it's more famous for its crafty ingenuity. It has a particular taste for large eggs, such as those of ostriches. Needless to say, the shell of an ostrich egg is quite strong, given that it must withstand the weight of an incubating ostrich, which can weigh up to 130 kg (290 lbs). And so, to get at the gooey golden goodness inside the Egyptian vulture will find itself a suitable rock, pick it up in its beak, and forcefully drop it onto the egg repeatedly until its cracks open — a behaviour it learns by observing other Egyptian vultures.

³ The bearded vulture, or lammergeier, lives and nests on the high mountain crags of southern Europe, parts of the Middle East, India, the Himalayas, and East Africa. Its diet is decidedly macabre — it eats almost exclusively bones, which make up some 90% of all its meals. If a bone is too large, the vulture picks it up in its talons, soars to a great height, and drops it. Shattered by the fall, the bearded vulture devours the small digestible pieces of bone.

**Where Does It Live?**

⛰️ Forests and savannahs, usually near water, and sometimes on oil palm plantations.
📍 Most of Sub-Saharan Africa; from the Gambia to Kenya, and southwards to north-eastern South Africa.

‘Least Concern’ as of 01 October, 2016.

IUCN

Size // Medium
Wingspan // 150 cm (4.9 ft)
Length // 60 cm (2 ft)
Weight // 1.4 - 1.7 kg (3 - 3.7 lbs)
Activity: Diurnal ☀️
Lifestyle: Social 👥
Lifespan: 25 - 30 years
Diet: Omnivore (70% herbivorous, 30% carnivorous)
Favorite Food: Palm nut fruit 🌰
Class: Aves
Order: Accipitriformes
Family: Accipitridae
Genus: Gypohierax
Species: G. angolensis

The palm-nut vulture is the only primarily herbivorous vulture species — around 70% of its diet is plant-material, mostly palm-nut fruits, and 30% is a miscellany of meaty (or fishy) foods. It does not often eat carrion.

Its vegetarian diet also includes the husks of palm-nut fruits, sweet dates, and occasionally seeds and grains.

The palm-nut vulture is a relatively small vulture; its wingspan is around 1.5 metres (almost 5 ft) while that of the Eurasian griffon vulture (Gyps fulvus), for example, can be as expansive as 2.7 metres (8.8 ft).

A juvenile palm-nut vulture has mottly brown plumage and yellowish facial skin. As it matures, it moults into its black and white plumage and its face turns pinkish-red.

The palm-nut vulture frequents forest edges and water boundaries — such as those of estuaries, rivers, and sea shores — where it is most likely to find oil palms. It can also be found in drier areas, where its palm fruit diet is supplied by human-cultivated plantations.

The palm-nut vulture is usually active early in the morning. It flies with rapid wing beats or soars with its tail fanned out, but doesn't rely on thermal air currents.