Chobe’s avian river hunters

This is the fifth post from my recent trip with CNP to the Chobe river. This trip has become an annual pilgrimage.

“And this, our life exempt from public haunt, finds tongues in trees, books in running brooks, sermons in stones and good in everything.

One touch of nature makes the whole world kin.”

 – William Shakespeare

No trip to the Chobe would be complete without a few images of the ubiquitous Fish-Eagle. The abundance of food dictates that the Chobe river area attracts many raptors. We also usually see a few African Harrier -Hawks, African Hawk-Eagles, Eagles, Goshawks and a number of Vulture species.  This trip we did not see any Goshawks, Hawk-Eagles or Vultures close up,  but we were fortunate enough to see a Western Banded Snake-Eagle on two occasions thanks to the eagle eyes of birders, Russell Warren and Stefan Swanepoel, on our boat.

The Fish-Eagle is a large, distinctive raptor. The female is bigger than the male and has a wingspan of about 2.4 m, almost 20% longer than the male. Her body is around 65cm in height.  The adult has very distinctive colouring with a white head, neck and chest and a chestnut-brown belly and leg feathers. It has large, powerful, wide black wings. This bird’s feathers have a distinctive lustre. Its face is yellow and featherless and it has a yellow cere and black beak.

Chobe river wildlife  photography

The Fish-Eagle, as its name suggests, is predominantly a fish hunter. Although this species mainly feeds on fish, it is an opportunistic hunter which is known to take a wider variety of prey. Waterbirds make up 30% of its diet. It also steals food from a wide range of predators and is known to harass Pel’s Fishing-Owl, Storks and Herons for their food. Lou and Veronica Coetzer have some wonderful images of a Fish -Eagle snatching a White-faced Whistling Duck and another grabbing a Banded Mongoose. Fish Eagles are also known to prey on Lesser Flamingos where the supply is plentiful.

Chobe river wildlife  photography

The Fish-Eagle hunts from a perch. Once prey is sighted, it launches from its perch, swoops low over the water, and at the critical moment pushes both feet forward to seize its target with its powerful talons. Its feet have rough soles which combined with their powerful talons enabling this Eagle to grasp slippery aquatic prey. Small fish are lifted up into a tree and eaten up on a branch but larger catches are dragged through the water to the shoreline. The Fish-Eagle uses its wings as paddles to propel itself through the water to the bank while holding onto its large prey with its talons.  It is estimated that only one in seven or eight fishing attempts are successful. The African Fish-Eagle rarely spends more than a quarter of an hour per day actively hunting but when it does the action is dramatic.

Chobe river wildlife  photographyChobe river wildlife  photography

With its distinctive plumage and evocative cry, the African Fish-Eagle is probably the most recognised bird of prey in Africa. Perched majestically on a dead stump sticking out of the river or in a high branch of a tree overlooking the water, the contrast between the white head, neck, chest and tail, and the chestnut belly, and the black wings, is unmistakable.

Chobe river wildlife  photography

Much less striking is the almost scruffy appearance of the immature African Fish-Eagle, with its generally dark-brown  with white mottled plumage. After the first year, the plumage begins to resemble that of the adult, but will take at least four to five years and numerous moults to reach full maturity. On occasion, from a distance, I have mistaken a juvenile Fish-Eagle for an Osprey, but the Osprey has a white chest and belly and a black eye stripe. Ospreys are not often seen along the Chobe river.

Chobe river wildlife  photography

Adult African Fish-Eagles are normally seen in pairs, but on large productive lakes and rivers, nests and roosts can be only a few hundred metres apart, and many birds can be found together in one area, as can be seen in the Okavango. The clear, ringing call “weee-ah hyo-hyo-hyo”, is made with the head thrown back. This must be one of the most evocative sounds along African rivers and lake shorelines. The male has a higher pitched call than the female.

Chobe river wildlife  photography

Calling and dueting, whilst perched or soaring, is an integral part of the breeding display. At times it is combined with dramatic aerial dives and falls, with pairs interlocking talons in mid-air. I have seen the calling while perched together and I have seen them calling with their heads flung back way up in the sky with massive cumulus clouds as their backdrop, but I have never seen their aerial displays.

“Knowledge can be communicated, but not wisdom. One can find it, live it and be fortified by it, do wonders through it, but one cannot communicate and teach it.”

 – Hermann Hesse

We regularly see African Harrier-Hawks patrolling the section of the river between the Kasane lodges upstream to the Chobe Game Lodge. Not only have these avian hunters got striking colouring but they have unique legs and are probably the birds most hated by the other birds along the river because they are adept nest raiders.

The African Harrier-Hawk, previously known as a Gymnogene, is a medium-sized raptor, roughly the size of a Fish-Eagle but more slender in build. Its upper parts, head and breast are pale grey. Its belly is finely barred with black and white feathers. It has broad pale grey wings, where its primaries are fringed with a broad black band, and it has black spots on the wing coverts. It has a broad white band across its black tail.

It also has a bare facial patch which is variable in colour, which is usually seen as bright yellow. When it calls near the nest, this patch becomes pink, and during display, face becomes various shades of orange to almost red. Its eyes are dark brown. It has a hooked short black beak. Its feet and legs are yellow, but uniquely they are double-jointed and its feet are small. This enables this avian hunter to be surprisingly dexterous.

Chobe river wildlife  photography

An unusual trait of this species is its double-jointed knees, which enable it to reach into otherwise inaccessible holes and cracks for prey. The African Harrier-Hawk is omnivorous, eating the fruit as well as hunting small vertebrates. It has the ability to climb, using wings as well as feet. It is known to raid the nests of cavity-nesters such as Pygmy Geese, Oxpeckers, Barbets and Wood-Hoopoes for their fledglings.

Chobe river wildlife  photography

You can see the Brown, Black-chested and Western Banded Snake-Eagles along the Chobe. I have seen a Black-chested Snake-Eagle but it was not close enough to photograph. I have been on the river  quite a few times with CNP but have never seen a Western Banded Snake-Eagle. Snake-Eagles have a distinctive shaped head and diet compared to Hawk-Eagles and Eagles. The only other southern Africa raptors who regularly eat snakes are Bateleurs and Secretary Birds.

““Here and there awareness is growing that man, far from being the overlord of all creation, is himself part of nature, subject to the same cosmic forces that control all other life. Man’s future welfare and probably even his survival depend upon his learning to live in harmony, rather than in combat, with these forces.”

 -Rachel Carson

The  Snake-Eagles have a distinctive wide head with large piercingly  eyes. The Brown and Black-chested Snake-Eagles have menacing large yellow eyes while the Southern and Western Banded Snake-Eagles have light-yellow to whitish irises.  Snake-Eagles are stocky and aggressive hunters. The Southern and Western Banded Snake-eagles are much more secretive than their Black Chested and Brown cousins, remaining relatively hidden in tree canopies of heavy woodland and forest areas .

Chobe river wildlife  photography

The Western Banded Snake Eagle is a greyish brown, as is the Southern Banded Snake-Eagle but the latter has conspicuous brown and white barring on its belly and top of its legs. The Western Banded has a short black tail, with broad white centre band and a fine white terminal band. It’s beak is black with deep yellow cere.  It is found in northern Botswana and along the northern border of Zimbabwe. The Southern-Banded is found mainly in Mozambique.

Snake-Eagles are specialist snake hunters but also supplement their diet with small reptiles. Their tarsi are covered in thick scales which protect them from snake bites. They are not immune to the venom but they also have a thick covering of breast and leg feathers which helps protect them from snake bites. They all hunt from a perch but the Southern and Western Banded Snake-Eagles are also known to catch snakes in trees.

Chobe river wildlife  photography

Snake-Eagles are thought to be nomadic, so do not breed in the same nest twice, though little is known about the Southern and Western Banded Snake Eagles breeding habits.

Chobe river wildlife  photography

We did not see vultures close up and only saw one Marabou Stork late one evening as we were returning to the lodge. This is not the right time of the year for Yellow-billed and Black Kites and we did not see African Hawk Eagles or any of the Goshawks. I can only assume there was so much food around that they did not need to stay close to the river.

Next week I will post a series of images of another type of avian hunter found alongside the river, waders. I hope you enjoyed the trip down the Chobe river looking at a select group of the many raptors which can be seen along the river.

“Without wilderness, we will eventually lose the capacity to understand our country. Our drive, our ruggedness, our unquenchable optimism and zeal and elan go back to the challenges of the untrammeled wilderness.

If we lose wilderness, we lose forever the knowledge of what was and what it might, with understanding and loving husbandry, yet become.

These are islands in time, with nothing to date them on the calendar of mankind. In these areas it is as though a person were looking backward into the ages and forward into untold years. Here are bits of eternity, which have a preciousness beyond all accounting.”

 – Harvey Broome

Co-founder, The Wilderness Society

“Without wilderness, we will eventually lose the capacity to understand America. Our drive, our ruggedness, our unquenchable optimism and zeal and elan go back to the challenges of the untrammeled wilderness.

Britain won its wars on the playing fields of Eton. America developed its mettle at the muddy gaps of the Cumberlands, in the swift rapids of its rivers, on the limitless reaches of its western plains, in the silent vastness of primeval forests, and in the blizzard-ridden passes of the Rockies and Coast ranges.

If we lose wilderness, we lose forever the knowledge of what the world was and what it might, with understanding and loving husbandry, yet become. These are islands in time — with nothing to date them on the calendar of mankind. In these areas it is as though a person were looking backward into the ages and forward untold years. Here are bits of eternity, which have a preciousness beyond all accounting.”

– Harvey Broome
Co-founder, The Wilderness Society

– See more at: http://wilderness.org/article/famous-quotes#sthash.8qNBPXYg.dpuf

“Without wilderness, we will eventually lose the capacity to understand America. Our drive, our ruggedness, our unquenchable optimism and zeal and elan go back to the challenges of the untrammeled wilderness.

Britain won its wars on the playing fields of Eton. America developed its mettle at the muddy gaps of the Cumberlands, in the swift rapids of its rivers, on the limitless reaches of its western plains, in the silent vastness of primeval forests, and in the blizzard-ridden passes of the Rockies and Coast ranges.

If we lose wilderness, we lose forever the knowledge of what the world was and what it might, with understanding and loving husbandry, yet become. These are islands in time — with nothing to date them on the calendar of mankind. In these areas it is as though a person were looking backward into the ages and forward untold years. Here are bits of eternity, which have a preciousness beyond all accounting.”

– Harvey Broome
Co-founder, The Wilderness Society

– See more at: http://wilderness.org/article/famous-quotes#sthash.8qNBPXYg.dpuf

Seek to understand nature, marvel at its interconnectedness and then let it be

Have fun

Mike

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