Allan Teo sent in an image of a pair of waders taken in India. Ong Tun Pin very kindly identified them to be non-breeding Black-tailed Godwit (Limosa limosa).

Allan thought the birds were fighting and he was right. They are usually peaceful, feeding as a flock. But as soon as food is limited, each bird vigorously defends its feeding territory. And when another moves in, there will always be a quarrel. In the image above, the two birds are engaged in a “mandibular clash” using their long bills to settle a territorial dispute.

This godwit is a winter visitor and passage migrant to Singapore and Malaysia. It breeds in Northeast Asia, moving south through the Indian subcontinent to reach Southeast Asia and even further to south New Guinea, north and west Australia. Fewer birds are now stopping over in Singapore, probably because of habitat loss.

The bird winters in sheltered waterways where there are intertidal mudflats and in sandy beaches, marshes, lake shores and rice fields. Food is chiefly invertebrates like insects, spiders, worms, molluscs, crustaceans, tadpoles and some seeds and berries.

The African Fish-eagle (Haliaeetus vocifer) is confined to Africa and seen near most waterways south of the Sahara. It feeds mainly on fish, with each pair defending a relatively small territory. Perched high on a tree, it regularly belts out a gull-like laugh to keep in contact with its mate and to warn off intruding fish-eagles.

Willis was at Lake Baringo in Kenya recently when he documented an African Fish-eagle’s dramatic flight from its perch to catch a lure fish in the water - HERE: 1 and 2.

This drama is being played regularly for the benefit of tourists. The local guide stuffs a fish with balsa wood to keep it afloat. He then throws the fish into the water and whistles loudly to the eagle. Obviously the bird is used to being fed this way and responds to the call.

All you need do is sit back with your camera ready and shoot your multiple sequential shots as the fish-eagle zooms in.

Once the eagle spots the fish, it lunges from its perch and swoops down low over the water (above). The sight of this large raptor sailing down with its prominent white head flanked by a pair of huge black wings that span some 2 metres is a stunning sight.

When in flight, the raptor has its feet stretched back and the toed tightly clutched. As it nears the water surface, it lowers its pair of feet and un-clutches all eight toes to reveal the eight long, curved and sharply pointed claws (above).

Once the prey is targeted, the bird plucks it from the water surface, gripped tightly within the grasp of one set of talons, and flies off (above).

The takeoff is preceded by the upstroke of its pair of huge wings (above) before the powerful down stroke that easily gets it airborne again (below). Subsequent flapping of its powerful wings takes the bird back to its perch or to dry land to enjoy its meal.

During the upstroke, the resulting air pressure forces the primaries feathers to be twisted open, resulting in less resistance to the air. Once the wings are fully raised (above), the downstroke causes air pressure to push the broader inner vane of the primaries up against the outer vane of the feather over it (below). This produces an unbroken surface, thus the resulting lift (bottom).

The entire drama unfolds within a brief two seconds and only a fast-action camera can document the sequence shots that are shown here.

All images by Willis.

This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.

On 2nd June 2008, Johnny Wee was witness to a Grey Heron (Ardea cinerea) at the Chinese Garden in Jurong catching a fish.

The heron was in the shallow water when it sighted a fish nearby. With a swift move, it caught the fish and flew off to dry land. There, it took about 15 minutes to manipulate the tilapia before it could swallow it head-first.

After swallowing the fish, it went to the water edge to drink - a total of five times before it was satisfied. The fish was flattish and broad. Was it a little too wide for the heron to swallow comfortably, so that it needed water for “lubrication”?

As with kingfishers, owls and bee-eaters, the indigestible parts are eventually regurgitated in the form of a pellet.

In early November 2007, Dr Chua Ee Kiam reported the presence of a Purple Heron (Ardea purpurea) at the Sungei Buloh Wetland Reserve with a torn lower jaw. Three months on it was still alive and well. Now, seven months on, Ee Kiam again encountered the heron and report on its efforts at feeding.

“Managed to photograph the Purple Heron (that was injured in the neck) feeding on a catfish in SBWR on 2nd June 2008. Initially I saw the heron landing on the water edge with the catfish between its beak. It then proceeded deeper to the mangrove forest to bash the fish. After a good 5-7 minutes, it carried the fish to the water edge to wash it (above).

“It tried to swallow the fish for more than ten times but the fish fell through the throat hole (above). I was quite glad that it finally managed to swallow the fish whole (below). Guess one has to keep trying despite the handicap. Enjoy the images.”

In the earlier post on the courtship behaviour of the Blue-eared Barbet (Megalaima australis) by Adrian Lim a.k.a wmw998, there was a mention of a prominent black throat pouch that the male displayed when making its mating call (below).

The male was described as puffing and blowing to expand his throat pouch. As the pouch expanded, it pushed aside the black feathers that make up the black upper breast band, exposing a smooth, rounded, black sac.

Adrian is of the view that “the sac is only a tool for making the call, I doubt it is for attracting the female. If you look at the shots carefully, you will notice that the breast of the male bird sinks in whenever the sac inflates or puffs up.”

Dr Geoffrey Davison was consulted and responded: “The throat of most birds bulges a bit when they call, but this looks rather extreme. I would have guessed that its crop is stuffed with food, and then when it is calling as well the upper part of the breast would swell even more.

“I have watched other species of barbets calling, and have not seen such an extreme swelling. On the photo it looks as though part of the patch is bare skin, and black - or is this perhaps a patch of feathers that have got wet and sticky from its food? If it is bare black skin then this does imply a signal function. The bases of the feathers within this patch are black.“

On seeing an enlarged image of the pouch, Geoff added: “Quite dramatic, isn’t it? The black skin is very clear in your tweaked version of the photo. I’m not familiar with the literature on anatomy, but many fruit-eating birds are able to store quantities of food in a gular pouch, for later regurgitation. It’s the equivalent of the macaques’ cheek pouches, though a different part of the anatomy (lower down in the oesophagus). I would be inclined to avoid the word ’sac’ for such a structure.

“Presumably a female barbet would be able to distinguish at a glance a male who has a supply of fruit ready (bigger black pouch = more food), and more inclined to allow copulation. I remember seeing something recently… about male birds rewarding the female who allows copulation by giving her fruit after she has submitted, rather than using fruit to tempt her beforehand.

“The other possibility is that this is a hollow structure, part of the air sac system, used as a resonance chamber to enhance sound production as it calls. These are not mutually exclusive possibilities (there could be both a resonating chamber in the air sac system and a pouch in the oesophagus) but not quite so easy to visualise how the two would work together.”

Morten Strange had this to say: “Bizarre image… This bird is not calling, the gular pouch seems to be stuffed to the brim with fruits…” while Wang Luan Keng suggested a ventriloquism function.

Yes, the pouch stores fruits, plenty of fruits. This species of barbet apparently has to offer a fruit for each act of copulation and usually a series occur one after another.

According to the literature, the skin of the throat or the neck on many non-passerine birds is bare, loose and distensible. In many instances it forms a pouch, especially in fruit-eating birds like hornbills (Kinnarid & O’Brien, 2007). The pouch comes in useful in the transporation of fruits to the nest to feed the chcks and/or mate.

In pelicans the pouch is for catching and holding fish for the young birds. That of the male Great Bustard (Otis tarda) is inflated in display (Garrod, 1874). In male frigatebirds (Fregata spp.) (above left), Marabou Stork (Leptoptilus crumeniferus) (above right), among others, similar pouches are inflated and displayed in courtship or social displays.

In grouse and Painted-Snipe (Rostratula benghalensis), the pouches increase the vocalisations by enlarging the sound resonating chamber (Stettenheim, 2000). Morten also pointed out that the Chestnut-winged Babbler (Stachyris erythroptera) produces low-pitched notes by inflating its neck, barring two patches of skin. The puffed-out neck-skin is a conspicuous blue or violet. His image is published in Collar & Robson (2007).

Image of barbet by Adrian Lim, those of frigatebird and stork by YC.

References:
1. Collar, N. J. & Robson, C. (2007). Family Timaliidae (Babblers). Pp. 70-291 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 12. Picathartes to Tits and Chikadees. Barcelona: Lynx Editions.
2. Garrod, A. H. (1874). On the “showing-off” of the Australian bustard (Eupodotis australis). Proc. Zool. Soc. London 1874, No. 31:471-473.
3. Kinnarid, M. F. & O’Brien, T. G. (2007). The ecology and conservation of Asian hornbills: Farmers of the forest. University of Chicago Press.
4. Short, L. L. & Horne, J. F. M. (2002). Family Capitonidae (Barbets). Pp. 140-219 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 7. Jacamars to Woodpeckers. Barcelona: Lynx Editions.
5. Stettenheim, P. S. (2000). The Integumentary morphology of modern birds - An overview. Amer. Zoologist 40:461-477.