Dendrophthoe pentandra is a common mistletoe plant that is semi-parasitic on wayside trees (above left). The mistletoe is spread by flowerpeckers and sunbirds that eat the fruits and excrete the sticky seeds when perching on the branches of shrubs and trees. These seeds are excreted stuck together, as the gummy covering that originally covered the seeds remain intact when passing through the digestive tract.

Now what do these birds do? Some simply wipe their bottoms against the branch to dislodge the seeds. Others use their beak or foot to remove the seeds from the posterior opening. In the process, these sticky seeds end up on the surface of the

branch where they slowly develop, sending a ‘sucker’ into the host’s tissues to tap water and nutrients. Green leaves develop so that the mistletoe can photosynthesise. It is thus partially parasitic on the host but it can do much damage in the long term.

In due course the mistletoe flowers (above right). These are so-called exploding flowers that need birds to trigger their opening. The images on the left show the Olive-backed Sunbird (Cinnyris jugularis) with its bill clamped on the flower bud. The pressure exerted on the bud will cause the flower to ‘explode’ and the petals to unfold. This allows the sunbird to insert its tongue into the flower to harvest the nectar.

An earlier post shows the Blue-crowned Hanging Parrots (Loriculus galgulus) harvesting nectar from the other mistletoe, Macrosolen cochinchinensis. As the bill of the parrot is differently constructed from that of sunbirds and flowerpeckers, the parrot needs to get at the nectar from the side of the flower, with the help of its broader tongue.

The images below show a male (left) and a female (right) Scarlet-backed Flowerpecker (Dicaeum cruentatum) among the Dendrophthoe pentandra mistletoe, obviously harvesting nectar. I am sure the birds need to use their bill to force the bud to open before they can get at the nectar, as with the sunbirds. However, I have yet to have photographic evidence.

In all three cases (sunbird, flowerpecker and parrot), the birds assist in the pollination of the mistletoe flowers, bribed by the offer of nectar.

Early one morning I found a fresh sprig of tembusu (Fagraea fragrans) with ripe berries still attached, on the top of my car’s boot (left). The car was parked under the porch with the rear end jutting out near to where one of my ceram palms (Rhopaloblaste ceramica) grow.

The palms are a favourite perch for many species of birds and any one of the fruit eating birds could have dropped the tembusu sprig. But do birds normally pick a fruiting sprig, rather than picking the fruits individually?

On the other hand the porch is a favourite roost of the Lesser Short-nosed Fruit Bat (Cynopterus brachyotis) (right).

The question posed is, was it a bird or a bat that deposited the tembusu sprig on my car? The consensus among the few who are familiar with bats is that it was a bat that was responsible.

Here are the reasons for suggesting bat:

Bats normally bring fruits back to their feeding roost to eat, especially large fruits. With small fruits, the bat usually eat them on the spot. In the case of tembusu whose fruits are small, it is possible that they may be eaten around the tree. However, to collect a sprig with more than a few fruits back to eat saves time and energy.

And are there instances of birds breaking off a sprig of tembusu bearing a few berries to be eaten somewhere else? Have there been any observations of such behaviour?

Is there any evidence of bats breaking off small branches for whatever reasons? Here, I can confidently say that it does happen.

My porch is a regular roosting site of these bats (above). At first a few came, leaving droppings on the ground below. Then one day a horde of them made themselves comfortable under the porch. And the mess thay left behind every morning could one day be mined for guano. So our helper chased them away. But a few still continue to come. And one or two roosted in the small Dracaena “Song of India” (Dracaena reflexa) tree, taking shelter under my porch whenever it rains (left top).

When these bats first started using the tree as a roost, I found a sprig of the dracaena on the ground below together with a number of fresh leaves (left bottom). Apparently the bats ripped them off the branch to clear a space to roost.

So bats do rip small branches off trees. And the tembusu sprig on my car most probably was left there by a bat.

We would love to hear from birders who have observed birds plucking sprigs bearing fruits to be eaten elsewhere. But then, do birders bother about bats?

Images by YC.

It has been two years since the Bird Ecology Study Group was formally constituted. The group’s blog has all along been highlighting various aspects of bird behaviour. To date, there are more than 500 posts involving 27 broad categories from feeding to nesting to inter-specific interactions.

Thanks to the willingness of photographers, birders and the nature loving public at large to share observations and images, the blog has developed into what it is today.

Join us in this talk that will reflect on the past two years of bird behaviour observations, and contribute to how we can move forward – to bring birding to a higher plane.

On 7th October 2007, Erik Mobrand wrote: “For the past few weeks we have had two noisy koels outside our window regularly. What is striking is that these individuals (a female and a male, perhaps juvenile) do not make the typical koel call. Instead, they have this hoarse squawk, which we hear many times during the day - not just at dawn and dusk, when we usually hear koels.

“What is going on? Do young koels try to imitate the House Crows they grew up with? The call has the same rhythm as the House Crow’s. I’ve seen these koels fighting with House Crows.”

We received two snapshots (below) and a video clip the next day and a note: “…We see this koel almost daily now out the window of our fourth floor flat. She sat in this tree calling on and on for perhaps two hours yesterday afternoon. A male making a similar call has also come by, though less frequently.”

Click on the link to view the video clip provided by Erik to hear the strange call: koel-clip.wmv

The bird in the images above is a female Asian Koel (Eudynamys scolopacea). And Asian Koels have a repertoire of different calls – at least seven loud calls have been reported. The usual call we hear in the mornings and evenings is the ascending loud ko-el-ko-el-ko-el-ko-el-ko-el-ko-el that begins slowly but may become faster with time. Then there is also the loud, harsh kroik-kroik-kroik. These are made by males and usually answered by other males that are around.

Click on the link provided to hear these calls, recorded by Sutari Supari and digitally processed by Wang Luan Keng: asian_koel.mp3

Wells (1999) describes an even-toned woik-woik-woik-woik that is made mainly at dusk, from roosting perches. This call sounds like what Erik recorded in the video. However, therecorded call was made during the afternoon, not at dusk.

Flying fledglings give a loud and harsh kaaa, rather like a young crow, when begging for food from its foster parents, the crows. So far, there is no evidence that juvenile koels imitate crows.

Until now!

Through Wang Luan Keng, the images and video clip from Erik were forwarded to Prof R B Payne, University of Michigan, Ann Arbor, Michigan, USA, the world’s foremost authority on cuckoos. Back came the reply:

“Thanks for sending the cuckoo video. The clip looks like a grown fledgling koel, plumae black with some whitish or buff bands on tail and wing, white spots on the back, and the call is like the begging call of crows.

“The call is like the calls of adult house crows as in the Birds of the Western Palearctic vol 8, 1994, p148, where the description says “food calls of older young a strangled ‘rekk-keck, reckkeck‘” which sounds about right, and the calls of the adults are similar too, in time (0.3-0.8 sec), pitch and frequency envelope (broadband, most sound at 1-2 kHz).

“Other crows in BWP do have words and figures of begging calls of young and the calls of adults - carrion crow has food-begging call of incubating female where the audiospectrogram looks a lot like your koel, and the word description sounds about the same too.

“Some other cuckoos have begging calls a lot like the begging calls of their foster species - African striped cuckoo Clamator levaillantii is the best known.

“I don’t know that a begging-call mimicry has been described for koels - for koels in Australia they say a hand-reared koel at nine weeks old was “a loud, varied, continual dialogue of sharp trills and squeaks akin to ‘wheeet-oop-weeet-wheet-wheeet-op” occasionally interspersed with high pitched screeches. The paper doesn’t show an audiospectrogram of this young bird. - Maller, C. J. and Jones, D. N. (2001) Vocal behaviour of the Common Koel, Eudynamys scolopacea, and implications for mating systems. Emu 101: 105-112.”

Images and video by Erik Mobrand.

References:
1. Payne, R.B. (1997). Family Cuculidae (cucoos). Pp.508-607 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 4. Sandgrouse to Cuckoos. Barcelona: Lynx Editions.
2. Wells, D.R. (1999). The birds of the Thai-Malay Peninsular. Vol. I, Non-passerines. Academic Press, London.

The Grey Heron (Ardea cinerea) is found around waters, be they fresh, brackish or salt. You can usually see them near rivers, lakes, marshes, mudflats, mangroves and rice fields. The bird feeds mainly on fish, although it also takes aquatic insects, amphibians, reptiles, some birds and even small rodents.

Its feeding time varies with location, either during the day (morning and evening) or at night or around dusk. It is usually a solitary feeder, fiercely defending its territory, although there are cases of group feeding.

Lee Tiah Khee’s dramatic images show how one bird tried to catch a fish but failed in its initial attempt. Undeterred, it succeeded in its subsequent attempt.

Like most herons, the Grey is a passive feeder, staying still for long periods or moving slowly in the water. The bird was spotted standing still in the shallow water waiting for prey. Apparently it spotted a fish approaching. When it was within range, the bird made a lightning attack, lunging its sharp bill into the wate (above). But it was not fast or accurate enough. The fish narrowly escaped by jumping out of the water (below).

In a flash the bird had its head out of the water and spotted the fish swimming away. In a split second it lunged at it again and succeeded the second time (below).

It seized the fish with its bill and picked it out of the water (above right). As it managed to catch it by the head, there was no need to reposition it before swallowing it whole (below).

As in the case of kingfishers, owls and bee-eaters, the indigestible parts of the prey are eventually regurgitated in the form of pellets…

Images by Lee Tiah Khee.