An earlier post gives the non-breeding, breeding (above) and transitional plumages of the White-winged Tern (Chlidonias leucopterus), also known as White-winged Black Tern documented by Dr Jonathan Cheah Weng Kwong at Kranji.

This is a migratory bird that moves down the Malay Peninsula to Singapore and beyond to as far as Australia to winter.

This tern is a generalist feeder, taking aquatic as well as terrestrial insects, small fish and tadpoles. It has a number of feeding techniques: aerial feeding, hawking flying insects, hover-dipping and contact-dipping. However, it does not plunge-dive.

The images provided (above, below) show the bird indulging in contact-dipping. Flying slowly and just above the water, it looks for a fish swimming just below the water surface. Once spotted, the bird turns it head downwards and sideways and plunges its bill into the water to snatch the fish. It simply continues with its flight with the fish securely clamped in its bill.

Reference:
Gochfeld, M. & Burger, J. (1996). Family Sternidae (Terns). Pp. 624-667 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 3. Hoatzin to Auks. Barcelona: Lynx Editions.

This is another documentation of the Stork-billed Kingfisher (Halcyon capensis) catching a young Common Tilapia (Oreochromis mossambicus) by Kennie Pan. This fish is not native to the region but introduced for food. This is probably the most successful and widely distributed of the tilapias.

The kingfisher was successful in catching this fish after three tries, diving at intervals of five to 20 minutes. The bird is often around Symphony Lake at the Singapore Botanic Gardens. Sometimes it flies off after a few unsuccessful dives, to return in the evening or the next day.

As Kennie wrote, “I realised that the Stork-billed is a ferocious predator when, instead of picking up the fish from the water by scooping it into it’s beak, it just dived-bombed directly at it’s target. It flapped its wings during the initial dive, to fold them as it gains momentum just before touching the water.

“The speed was so fast that most probably the fish had little chance of escaping. Due to the powerful impact, the beak just pierced right through the fish, probably killing it instantly, though it still whacked the fish against the branch when it returned to its favourite perch. After about three minutes of whacking, it flew off with its catch.

“I have witnessed successful hunting of fish by two of our local eagles - the White-bellied Sea Eagle (Haliaeetus leucogaster) (below left) at Jurong Lake and the Brahminy Kite (Haliastur indus) (below right) at East Coast.

“I noticed that while the White-bellied Sea Eagle has a rather gentle approach to catch its prey, the Brahminy Kite closed its wings and dived down to its prey. I was wondering whether they are the result of different conditions (gentle lake versus choppy sea) or different strategies for survival adopted by the two different eagles.

“I also noticed that they hunted when it was cooler i.e. when the sun is hidden by the clouds or when the storm clouds gather.

Myron Tay
July 2008

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 www.naturepixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.