The Giant’s Castle hide was built in 1967 to enable birders and photographers to better appreciate vultures, especially the Bearded vulture. The remaining southern African population of Bearded vultures live in the Maluti-Drakensberg mountains in South Africa. While you are likely to see a variety of birds from the hide, the grand prize is the Bearded vulture because of its rarity and unusualness.

“Our relationship with nature is more one of being than having. We are nature: we do not have nature.” ~ Steven Harper

According to the African Raptor Centre, there are estimated to be 100 breeding pairs and 320 birds remaining in the wild in the southern hemisphere. This makes it one of the most threatened vultures in southern Africa. The decline in numbers has been caused by less food availability due to the expansion of human settlements, electrocution by overhead power lines, collisions with wind turbines, and farmers poisoning bait to kill Jackals. Bearded vulture body parts are also used in ceremonial and traditional medicine purposes.

The vulture hide in the Giant’s Castle Nature Reserve is located on a shelf on the eastern side of the Bushman’s river valley. The shelf, where most of the feeding occurs, expands from just wider than the hide itself at the north east end of the shelf, about 25 metres wide in the middle of the shelf and 50 metres at the south eastern end of the shelf. One of the photographic highlights of your time in the hide will be when a Bearded vulture lands on the south eastern end of the shelf.

If you are lucky you may see the Bearded vulture flying in to land on the south eastern shelf. Alternatively, it may suddenly appear over the edge of the shelf. So often it looks like it is going to land only to turn away at the last moment. Every time this happens there is great excitement in the hide.

The uncertainty of how or when a raptor will come in to land on the rock shelf dictates that you have to be alert and ready to shoot photographically all the time. Fortunately, my avid birding wife, Helen, is an excellent spotter which significantly improves my photographic hit rate.

Interestingly, despite its large size the Bearded vulture seems to be relatively timid in front of the hide, perhaps it is just wary. On this particular occasion, the adult Bearded vulture landed at the far end of the shelf. It did not walk over to the many bones scattered on the shelf but kept looking over the edge of the shelf and after a minute or so it took off again.

The adult Bearded vulture is mostly dark gray, rusty, and whitish in colour. It has grey-blue to grey-black upperparts. Its creamy-coloured forehead contrasts against a black band across the eyes and lores, and bristles under the chin, which form a black beard that gives the bird its English name.

The Bearded vulture is one of the largest vultures in Africa with a wingspan of up to 2.9 metres. It can stand up to 125 centimetres in height and weigh up to just under eight kilograms. It is the only raptor with a beard. This beard gives the vulture its scientific name ‘Gypaetus barbatus’ which literally means ‘bearded vulture-eagle’. Bearded Vultures are big shaggy looking raptors which look more like eagles than vultures. The Ruppell’s Griffon and Lappet-faced vultures are heavier than the Bearded but have a similar wingspan.

It is also the only bird known to decorate itself. The plumage on the chest, neck, shoulders and legs of the adult Bearded vulture are a creamy-white. This vulture stains it’s creamy-white legs, chest and neck feathers a rusty red by bathing in soils or water rich in red iron oxide deposits. The reason for these vultures staining their white chest, legs and neck feathers is not fully known. One theory postulated is that the colour displays their prowess. Another theory is the iron oxide provides an antibacterial effect. This species of vulture cannot produce carotenoids, which are antioxidant compounds that protect cells from free radicals in the body. Many bird species acquire carotenoids through their diets but the Bearded vultures’ bone and marrow diet does not provide these antioxidants. Another intriguing idea is that the intensity of plumage colour of Bearded vultures with access to red soils was correlated with age. The older the adult the more brightly coloured.

“The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.” ~ Rachel Carson

Another unusual feature of the Bearded vulture is its ability to concentrate blood in the scleral ring around the eye. This is different to the carotenoids which pigment the lores and base of the beak of the Bateleur and African Harrier-hawk. The latter two raptors can also concentrate blood in their lores to produce an intense red colour. Again it is speculated that Bearded vultures evolved the large scleral ring and the pale yellow iris to convey information about the status of the individual. This signal is reinforced by staining their plumage with iron oxide, which ore closely matches the iris colour in the species.

The scleral ring in birds consists of ossicles that are fixed as small plates by cartilage joints and have no articulation to other parts of the skeleton. The scleral ring is red because it is full of blood. It is thought that when a Bearded vulture is stressed or feels threatened, it forces more blood into the scleral ring causing it to expand and turn more of the eye a red colour.

The shape of a Bearded vulture’s wing is also noteworthy. Its wing is classified as a passive soaring wing. This wing type has a low aspect ratio, meaning the ratio of the wing span to the average width is low even though it has such large wings. Low-aspect-ratio wings generally provide greater manoeuvrability but at the cost of greater drag (air resistance).

Air from high-pressure areas beneath the wings flows over the wingtips into the low-pressure areas above the wings causing wingtip turbulence, which increases drag. Eagles and vultures reduce this drag problem by flying with their primary feathers extended, creating slots between them. Each primary feather serves as an individual high-aspect-ratio wing, reducing wingtip turbulence and lowering the stalling speed of the wing so that the bird can remain aloft at a slower speed.

The vulture’s wing loading is also low because the ratio of the bird’s weight to wing area is low. This factor allows the vulture to glide with extended wings for long periods. The large wings are harder to flap so the Bearded vulture lands on the edge of a cliff or rock shelf where it can dive off when it wants to get flying again.

The mechanics of flapping flight become harder the larger the bird because the mass increases faster than length. A bird twice as long as another is on average four times as heavy.

Bearded vultures are master wind riders. They make use of updraughts produced when the wind blows over the mountain ridges to get and stay airborne. They also gain height by tacking or flying in alternate directions at right angles to the direction of flow of the wind. There are many wonderful sightings of Bearded vultures flying past the hide, in some cases 30 metres away at eye level.

These vultures also catch thermals to gain height and are at times at least 400 to 500 metres above the hide. They can also be seen flying low through the Bushman’s river valley possibly only 30 metres above the valley floor looking for food.

“Wonderful how completely everything in wild nature fits into us, as if truly part and parent of us. The sun shines not on us, but in us. The rivers flow not past, but through us, thrilling, tingling, vibrating every fiber and cell of the substance of our bodies, making them glide and sing.” ~ John Muir

Bearded vultures do land on large rocks near the Bushman river valley floor. They can sit on the rock for as long as half an hour just looking around. The rock needs to be high enough for the Bearded vulture to dive off.

We spent a few days in the hide during winter and at times it was very cold. On one day it snowed on the upper sections of the higher mountains. This got me to thinking about how these vultures keep warm enough to fly in the really cold air for extended periods.

These vultures are well-adapted to their cold mountainous hunting grounds. Their broad, stiff overlapping contour feathers prevent the icy wind from penetrating the soft, insulating down underneath. Bearded vultures spend 80% of daylight hours soaring gracefully on the wing with their bare feet tucked in their shaggy feathers to keep them warm.

When feeding, Bearded vultures can swallow whole or bite through brittle bones as large 25cm long and 3.5 cm wide. Their powerful digestive system quickly dissolves even large pieces of bone. Their stomach contains a strong acid (with an estimated ph of 1) which is capable of dissolving the digested bones in just 24 hours.

These vultures also seek the bone marrow. To access the marrow from bones too large to swallow the Bearded vulture has to crack the bones open. To do this they carry the large intact bone to a height of between 50 metres and 150 metres above the ground and then drop it onto specific flat rocks below called ossuaries; this smashes the bone into smaller pieces exposing the nutritious marrow. After dropping the large bone, the Bearded vulture descends to inspect it and may repeat the process if the bone is not sufficiently broken. Once cracked the Bearded vulture extracts the exposed bone-marrow with its rough, scoop-like tongues. The ‘dropping skill’ is learned and requires extensive practice by immature birds which can take up to seven years to master. The energy content of this marrow diet is 15% higher than a meat diet, but requires a lot more work.

Each day you have booked the hide, you are given a bucket of bones to put out for the Bearded vultures. There have been many days when the Bearded vultures repeatedly glided past the shelf in front of the hide where the bones are placed and they never landed to swallow or pick up bones. All the while the White-necked ravens were tucking into the meat and fat on the bones with relish. The passing vultures were definitely looking and seeing the bones but seemed happy to continue gliding back and forth along the ridge supported by the updraft. The Bearded Vulture, like other Old World Vultures, depends on sight to find its food. This is in contrast to many New World vultures that have a highly developed sense of smell.

Vultures can be divided into two age categories. New World vultures, which are from North, Central, and South America; and Old World vultures are from Africa, Asia, and Europe. Old World vultures have also been around longer than the New World vultures.

Old World vultures look like their eagle and hawk relatives. They have large, grasping talons, a voice box so can vocalise, and build nests made of sticks on rocky platforms or in trees. They have stronger feet than the New World vultures, but they are not designed for grasping, and large broad wings that allow them to stay aloft for most of the day, and a large, powerful beak with a hooked tip. Bearded vultures are usually silent but when participating in a breeding display they communicate by means of a high-pitched whistle. I personally have never heard the vocalisation from a Bearded vulture.

The Bearded vulture tends to be solitary, but when breeding they may be seen in pairs. The female is larger than the male.

The Bearded vulture reaches sexual maturity between five and seven years of age. Interestingly, the age of the Bearded vulture in the period until it reaches sexual maturity can be reasonably accurately estimated from the colour of its plumage, especially the head and neck. The next image shows an adult Bearded vulture flying with its juvenile.

The age of the juvenile to adulthood can be estimated by looking at the transformation colouration. Roberts Birds of Southern Africa gives an illustrated aging chart of the Bearded vulture. The juvenile’s head, neck and belly changes colour as do the secondary wing feathers and the wing coverts.

The juvenile fledges about 110 to 130 days after hatching, and it depends on its parents for food for between seven and 12 months. In its second year, the juvenile’s head is entirely black and the first signs of a beard is growing. The breast is mottled black, brown with tinges of fawn colour. The scapular shaped tail feathers are black.

In the third year, the head shows the first signs of white on the neck and cheeks, and the eye brow is starting to whiten. The breast feathers are becoming progressively lighter with more fawn colouring in them.

In the fourth year, the lores are prominently black, the cheeks are whiter and the forehead is becoming white. In the fifth year, the face and neck are even whiter and the underwing coverts are becoming more mottled while the secondaries remain black.

In the fifth year, the head and neck are whitening further and the secondaries are becoming lighter and the underwing coverts are becoming blacker. The upper wing coverts are becoming more mottled black, white and fawn coloured.

By the sixth year the head and neck feather are progressively lighter and often have more iron oxide red colouring. The chest and belly feathers become progressively whiter coloured with red oxide and the secondaries are lighter.

Most people think that a bird’s knee bends backward, but in fact what we think looks like a knee is actually the bird’s ankle/heel joint. The knee is hidden under feathers close to the bird’s body. Since everything under the ankle is the foot, it is easy to see that a bird actually walks on its toes. The Bearded vulture has anisodactylic feet meaning that it has three toes pointing forward and first one, the hallux, pointing backwards.

On our last day in the hide, we were fortunate to have a juvenile Bearded vulture frequently fly past close to the hide at eye level.

The ravens drop many of the bones over the edge of the feeding shelf so the Bearded vultures fly just below the ridge looking for the dropped bones. Looking down on the juvenile Bearded vulture you can see the beautifully coloured upper wing coverts and its scapular shaped tail feathers.

After a few fly pasts, the juvenile landed on a large rock shelf below the hide.

This gave me an opportunity to get a close up of the juvenile showing the wonderful colouring of its head, neck, chest, belly and legs. These vultures always perched on a rock shelf with a steep drop off so that it could take off by just diving off the shelf.

The intriguing aspect of being in the hide is that you have time to ponder about all the adaptations and behaviours of the birds you are watching. Inevitably, more questions arise accompanied by more wonder. Over a few days in the hide you get to understand the behavioural patterns of the various birds which helps anticipate more interesting photographs. Invariably, we would get up to the hide at first light, which in winter was around 6h15. The sunshine only fell on the hide shelf around 7h30. This gave us time to get our cameras set up and have a cup of hot coffee and rusk to warm up. Once the sunshine had cast light on the hide shelf we put out some of the bones at strategic places with the hope of getting particular types of photographs. Within minutes of the bones being put out, the White-necked ravens and Red-winged starlings would appear and begin to feast on the flesh and fat on the bones. The race was then on as to whether the ravens, starlings and Black-backed jackals would finish off the bones before one of our sought after raptors arrived. Although we spent nine to 10 hours in the hide each day it was great fascinating and fun.

“The fact is that no species has ever had such wholesale control over everything on Earth, living or dead, as we now have. That lays upon us, whether we like it or not, an awesome responsibility. In our hands now lies not only our own future, but that of all other living creatures with whom we share the Earth.”~ David Attenborough

Explore, seek to understand, marvel at its interconnectedness and let it be.

Have fun, Mike