Archive for October, 2006

More on Tiger Shrike

An earlier posting on how a Tiger Shrike (Lanius tigrinus) meticulously dismember a scarab beetle lamented the fact that there has not been any report of the bird taking vertebrates in Singapore. It is very possible that someone may have seen the incident to subsequently forget about it. This is exactly the situation. After reading the blog, Mike Hooper kindly sent an image of a Tiger Shrike swallowing a lizard, seen at the Kallang Riverside Park on 7th October 2006 (above).

And according to our bird specialist R. Subaraj: “…not enough of the lizard remains visible for a positive identification but I suspect that it might be a young Changeable Lizard (Calotes versicolor), based on the long tail and the yellowish colouration of what is visible.

And Subaraj continued: “Several years ago, at Marina East, I came across the headless corpse of a Yellow-rumped Flycatcher (Ficedula zanthopygia), a migrant, impaled on a thorn of a short tree. Though there was no direct evidence, I suspect that it was the doing of the local Long-tailed Shrike (Lanius schach).

“In Malaysia, I once came across the “larder” of a wintering Brown Shrike (Lanius cristatus). It had impaled a selection of insects onto the barb wire on the top of a perimeter fence! Modern adaptation?” Coming back to the shrikes, according to Chan Yoke Meng, these birds have no problem feeding on caterpillars, spiders and other invertebrates. They usually swallow them within seconds (above: top Brown, lower Tiger). As with raptors, bee-eaters (a,b), herons and kingfishers, shrikes cast pellets of undigested parts of the food they eat. The image above shows the bird after casting the pellet while the lower image shows the pellet. Beetle parts are clearly seen.
Input by Mike Hooper, R. Subaraj and Chan Yoke Meng. Images by Mike (top) and Meng (the rest).

How the Tiger Shrike dismantled a beetle

Shrikes are songbirds. But when they hunt they behave like little raptors. An earlier posting showed how aggressive a juvenile Tiger Shrike (Lanius tigrinus) was when eyeing the white-eyes in a cage. Given a chance we are sure it would have devoured one of the caged birds. The diet of these shrikes consists of large insects and small vertebrates that include songbirds, reptiles, rodents and even mammals. So far there has not been any local report of a shrike capturing a vertebrate prey. But in mid-September 2006 we observed a juvenile Tiger Shrike manipulating a large scarab beetle (above).
The juvenile bird was on a perch, looking handsome and posing for the camera. But it was actually eyeing the surroundings. Suddenly it dived towards the ground and caught hold of a scarab beetle by one of its legs (above). Returning to its perch and with one of its feet holding down the beetle, it started to stab the wriggling insect with its sharp beak. Then, holding on to the head (above), it thrashed it against the branch until it managed to tear away the upper portion from the body and got a first taste of its crunchy meal (below). Beetles have a thick protective sheath, the elytra, over the back portion of the body. This is made up of the hardened forewings, tucked under which is the pair of functioning membranous wings. The other parts of the body have a covering of thick cuticle. So beetles are generally well protected from predators. But not from shrikes! The shrike next tried to crush the headless beetle with its powerful beak (above). But the beetle’s elytra proved too hard. With another swift swing it got the elytra detached. The bird then tried to squeeze out the soft tissue and in the process nearly lost its grip on the perch. It continued to crush the thorax with its powerful jaws, pulling at the soft tissues, determined to get to the succulent part. At this point the beetle thorax was totally mangled (above). Swallowing the thoracic portion, it tried to swallow the remaining part but could not succeed (above). It was either too hard or too big. It tried to crush and flatten it further in between its mandibles before finally finishing its meal (below).
Tha above account is by Melinda Chan. All images by Chan Yoke Meng. The beetle was identified with the help of Dr Cheong Loong Fah

Black-naped Tern’s first flight

“The Black-naped Tern (Sterna sumatrana) nests in a shallow depression on the rocky surface of small outcrops. Generally, two eggs are laid and incubated by both parents. Soon after hatching, the chicks wander off from the exposed nest to seek shelter behind some boulders or whatever. With the male bird flying off to look for food, the female generally keeps a watch on the offsprings.

“The period to fledgling is slightly less than a month. All through this period and even after, a chick will continuously beg for food from its parents. Days before fledgling, it will exercise its wings, especially when a strong wind blows through (above). The parent bird would generally refrain from feeding it in an attempt to encourage it to make the first move into flight. No doubt its most anxious moment is just before it attempts at flying.

“The juvenile will spread its wings, no doubt to understand how the wind catches for lift. With aid from blasts of continuous wind, the juvenile trains for its first liftoff (above). As it experiments further, the parents would keep a close watch to check progress (below).

“Sometimes it needs a timely peck from the parent to trigger take off (above). This is done when the parent feels that the juvenile is ready.

“The magical moment arrives and the juvenile makes its first flight. And I was just as exhilarated and filled with awe as the juvenile itself. Once the juvenile fledges, the parent takes off immediately after it to keep check on its progress and possibly to orientate it on its maiden flight (above).

“The juvenile, although excited to fly, learns to use its other tail functions, like flap control and maneuvering (above). Once satisfied that the fledgling has mastered the basics of flight, the parent watches from the back, as it tries to glide around (below).

“The moment of pride for the parent as the juvenile comes in tandem to demonstrate its own proficiency, like a confirmation of flight-hood (below, left).

“Wary that the juvenile may not have what it takes, especially when a predator is near, it gives a timely peck to bring it back to the landing spot (above, right). The above occur within a short moment that generally escape notice. To be able to catch them on film is both rare and powerful - maybe a chance of a lifetime to experience. Within days after, the juvenile followed its parents on a journey to the ends of the earth (below).

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“Avian photography can be fulfilling - so as long as you keep your distance and do not cause distress to your subjects.”

Dr Jonathan Cheah Weng Kwong and Xin spent time studying these birds and documenting the various stages of this exciting event as outlined above. All images by Dr Cheah.

Tanimbar Corella and Yellow-crested Cockatoo

If you are at Changi Village and hear loud screeching, look around you, especially at the many tall angsana (Pterocarpus indicus) trees along the road. These are the Tanimbar Corella (Cacatua goffini) (above), also known as Tanimbar Cockatoo. There are usually about five birds around these trees and they are hole nesters.

There are up to 20 such corellas in the Loyang/Changi area. They are also found elsewhere in Singapore, including about 40 on Sentosa.

The other parrot commonly using these trees are the Red-breasted Parakeet (Psittacula alexandri), also known as the Moustached Parakeet. There are also about three Yellow-crested Cockatoos (Cacatua sulphurea) (below) around Changi but they hardly visit the village.

All the above birds are not natives of Singapore. Tanimbar Corella is native to the Tanimbar Islands of Wallacea. The Red-breasted Parakeet has always been found in Java, Bali, India, Andaman Isle, China, Indochina, Myanmar, Thailand, Sumatra, Borneo and Java. Both were introduced to Singapore three to four decades ago through the bird trade. All have established themselves in Singapore and have feral (i.e. tame birds that returned to the wild) breeding populations.

In Singapore, the Tanimbar Corella feeds on the fruits of various wayside trees like Sea Almond (Terminalia catappa), pong pong (Cerbera odollam) and starfruit (Averrhoa carambola). They are wasteful eaters, pecking away a few morsels only.

One or two Sulphur-crested Cockatoos (Cacatua galerita), also escapees, have recently been seen in Sentosa.

PS: All three cockatoos are endangered. Yellow-crested and Tanimbar are listed in Appendix I of CITES while Sulphur-crested is in Appendix 2. This means that commercial trade in these birds is prohibited as of 14th June 2006.

Text by R. Subaraj, images by YC (top) and Meng and Melinda Chan (bottom).

A House Crow went fishing

Crows are omnivorous. This means that they eat anything and everything, from grain, fruits, flower nectar, insects, eggs and birdlings, small mammals and what have you. They are scavengers, thriving where there are scraps of food available. That is why they are so successful around urban areas.

We have posted accounts of crows attacking and eating a rat and a bat. We also have an account of a White-bellied Sea Eagle (Haliaeetus leucogaster) catching a rat swimming in the sea off Changi. But this is the first time we have an account of a House Crow (Corvus splendens) actually fishing.

Meng and Melinda Chan witnessed a House Crow in Punggol last year quietly standing on a rock by the sea. Suddenly it dived into the water and emerged with a fish. With the fish firmly in its bill, it bashed it against the rock until it was stunned or probably dead. Then it started ripping it apart and eating it piece by piece. It was then about 7.00 pm in the evening and the light was low, so the image they managed to capture was not as bright and crisp as they would like it to be.

For the records, there have been reports of House Crows picking fish from shallow water or even plunging into deeper water to fish.

Input and image by Meng and Melinda Chan. Thanks to Kok Hui we have the correct ID of the bird in the above image.

Reference: Madge, S. & Burn, H. (1994). Crows and jays. London: Christopher Helm.

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