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Wednesday, January 10, 2007

Little Egret fishing

Little Egret fishing

K.C. Tsang was standing on the banks of the Sungei Punggol one morning in November 2006 watching all the Little Egrets (Egretta garzetta) massing along the banks very near to the water’s edge. Suddenly one of them took off, hovered over the surface of the water and within a split second plunged it long bill into the water and grabbed a fish.

He noticed that the birds always had the sun shining from the front of them in the morning, when hovering and fishing. There would thus be no shadow cast to alert the fish.

And K.C. added, “I though that these fellows feed mostly on insects among the grass. This has been observed most of the time. This is something new to me. Maybe a person with a video cam would be able to capture the whole episode.”

Our bird specialist R. Subaraj has this to say: “Little Egrets mainly feed by walking along the water's edge or in the shallows, catching fish by stabbing at them with it's long bill. The flying over the surface technique that you describe is therefore interesting and obviously an adaptation to take advantage of a situation. “The egrets feeding on grasshoppers in the fields around Singapore are usually Cattle Egrets (Bubulcus ibis) (above). This is their natural behaviour. Intermediate (Mesophoyx intermedia) and Little will also do that from time to time... but it is not their normal way of feeding.”

Input by K.C. Tsang; image of Little Egret by KC and Cattle Egret by John Lynn.

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Thursday, November 30, 2006

Common Kingfisher: Hovering

Common Kingfisher: Hovering

On the morning of 21st November 2006, KC Tsang was admiring a Common Kingfisher (Alcedo atthis) quietly perching on a branch of a tree. He had his camera setup ready and so took a shot of the bird (above). Then suddenly it flew off and hovered above the ground, “like a helicopter” he wrote (below). The bird then swooped down on the grass below and caught an insect. As KC wrote: “According to my long-time birder friend… this must be a new behaviour.” Well, most kingfishers hunt from a high perch, splash-diving into the water or dropping onto the ground to catch a prey (below). These birds take insects and other invertebrates, crustaceans, fishes, frogs, geckos, snakes and sometimes even small birds. Several species use the technique of hovering to forage but only in the Pied Kingfisher (Ceryle rudis) has the technique been perfected. Lui Jianzhong was kind enough to share his images of a hovering Common Kingfisher taken in Hongkong some time ago. The bird was hovering over the mudflat looking for a potential meal like mudskippers, fishes or shrimps (above and below). Hovering is an energy-intensive activity, achieved by beating the wings more or less horizontally – to provide lift but not thrust. The ability to hover for long periods is advantageous when foraging in areas away from a nearby perch. This means that the bird can maximize its time for hunting, rather than returning to a nearby perch to scan the area.

Our bird specialist R. Subaraj has this to say: "This is not new behaviour! The Common Kingfisher is well known for using this method in addition to fishing from a perch and has been observed and documented hovering on several occasions in Singapore and Malaysia."

Input by KC Tsang and Lui Jianzhong; images by KC (top three) and Jianzhong (bottom two).

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