In May-July 2006 Mark Chan documented the breeding of a pair of Changeable Hawk Eagle (Spizaetus cirrhatus), both pale morph. The chick that resulted in the union was distinctly a pale morph. The head, neck and underparts were totally white with no markings at all. The local subspecies is limnaeetus.

In June the following year, Johnny Wee and Chan Yoke Meng managed to document the mating of a pale and a dark morph in Singapore (above). Like most other eagles, they build their nest of sticks lodged between the forks of branches in tall trees.

The chick in this case was a dark morph (below left). On 22nd June 2007, the dark morph parent was seen flying past the nest with food in its bill (below right). Was it trying to persuade the chick to fledge by not feeding it in the nest?

Apparently the parent failed as the very next day the chick was seen feeding on a rat in the nest, swallowing it whole (below).

The chick was regularly testing its wings in the nest, as seen on 27th June when the image below (left) was taken. It fledged on or before 6th July as the bird was then seen outside the nest (below right). The dark x pale morph progeny was not all dark, as there were distinct white patches on the breast and flanks (bleow).

The fledged chick returned regularly to the nesting tree for feeding sessions and to roost on the branches.

The Changeable Hawk Eagle exists in two distinct forms or colour morphs. This is a common form of polymorphism (poly = many; morph = form) that occurs in birds, particularly birds of prey.

In this eagle, there is a pale morph and a dark morph. The adult pale morph appears dark brown above and whitish with dark streaks below. Adult dark morph is totally blackish. Each morph may have specific advantages in certain habitats, like certain survival and reproductive advantages. However, what these are, we do not know.

Images by Johnny (chick eating rat) and Chan Yoke Meng (the rest).

In January 2006 I had an exciting encounter with a family of Scaly-breasted Munias (Lonchura punctulata) visiting my neighbour’s well-maintained garden. They came quietly and by chance I noticed them foraging among the grassy weeds. Then again, in September 2007 I had another excounter. This time, in my unkempt, weedy garden, foraging grass seeds.

The birds worked fast, pulling the grass inflorescence growing in my potted plants and stuffing the seeds in their bills. They worked from the ground, perching from the stunted bougainvillea plants growing from the pots as well as from the edge of the pots. They moved about rapidly, working different plants as they went about their foraging expedition. Then they were gone.

Obviously, munias are seed eaters. I looked up the limited literature and found that they go for the smaller grasses, like carpet grass (Axonopus compressus), Bermuda grass (Cynodon dactylon), goose grass (Eleusine indica), buffalo grass (Paspalum conjugatum) and panic grass (Panicum spp.) (above, from left to right). I am sure they take seeds of other grasses as well, but to birders, well, grass is grass. So we await more detailed observations from those who are more inclined towards plants, especially grasses. Or photographers, from whose images botanists can try identify the grasses.

In the images at the top of the page, the one on the left, taken by KC Tsang, shows a munia perched on a stalk of a ?panic grass while the other two images show the bird eating the seeds of carpet grass.

The birds also eat seeds of sedges (Cyperaceae) that some birders call grasses (Gramineae), but let’s not split hairs, and herbs like common snakeweed (Stachytarpheta indica).

Wells (2007) reports that the bird also “exploits the cones of casuarinas, often high in the crown of mature trees… also takes quantities of the nutrient-rich filamentous alga Spirogyra, found in open, wet places on paddyland etc.”

The images above (left) show a sprig of casuarina (Casuarina equisetifolia) with a close-up of a fruit that is still unripe. On ripening the many sharp projecting points will split to expose the seeds. The top right image shows a single filament of Spirogyra, also known as water silk and mermaid’s tresses, while the bottom image is an enlarged view of three filaments. The green spirals within the filaments are the chloroplasts, thus the generic name, Spirogyra. This is a microscopic green alga that grows in relatively unpolluted, stagnant or slow-moving freshwater (drains, ponds), forming masses of slimy, green, unbranched threads.

Images by KC Tsang (munia, top of page, left) and YC (others).

References:
1. Wee, Y. C. & R. Corlett (1986). The city and the forest: plant life in urban Singapore. Singapore University Press.
2. Wells, D.R. (2007). The birds of the Thai-Malay Peninsular. Vol. II, Passerines. Christopher Helm, London.

The Bat Hawk (Macheiramphus alcinus) is a raptor found in the sub-Saharan Africa, Madagascar, Malay Peninsular, Sumatra, Banka, Borneo, Sulawesi and New Guinea. The bird is a rare visitor to Singapore.

This is a fairly large black hawk with a distinct crest (left). It is often not noticed because it is active only at night. During the day it perches quietly, almost horizontally on the branch of a tall tree, seldom leaving, even for a short while. It becomes active at dusk when it goes on the lookout for small bats, swifts, swallows and large insects.

Prey is caught using the hawk’s talons, usually after a high-speed chase, and transferred to the mouth to be swallowed whole while still in the air. As the period available for hunting is short - at dusk until darkness descends and a short period in the early morning – it needs to hunt where prey is plentiful, like at a cave entrance.

The image below, taken by Wilson Yang, clearly shows one Bat Hawk with a few others among the stream of bats emerging from their roost, probably a cave, in Borneo.

Observations made near a cave in Zambia record a foraging Bat Hawk catching, on an average, seven insectivorous bats during six consecutive nights (Black et al., 1979). As the bats flew out of the cave, the hawk intercepted them and either struck. caught or failed to make contact. The feeding bouts lasted 18.3 minutes per night and the success rate was 49%. The time between killing and swallowing of each bat (average weight 56.3 g) was 6.0 seconds.

Another specialist bat predator is the African Harrier-hawk (Polyboroides typus). There are also a number of owls, goshawks, peregrines and kestrels that occasionally catch bats.

Raptors predating on bats are better known than birds predated by bats. However, there have been recent accounts of giant bats snatching birds from the night sky (1, 2).

Image of hawk courtesy of Lim Kim Chye and Yian, that of bats by Wilson Yang. Check out Wilson’s Flickr site.

References:
1. Altringham, J.D. (1996). Bats: Biology and behaviour. Oxford: University Press.
2. Black, H.L., Howard, G. & Stjernstedt, R. (1979). Observations on the feeding behavior of the Bat Hawk (Macheiramphus alcinus). Biotropica 11(1):18-21.
3. Fenton, M. B., Cumming, D. H. M. & Oxley, D. J. (1977). Prey of Bat Hawks and availability of bats. The Condor, 9:495-497.
4. Madoc, G. C. (1956). An introduction to Malayan birds. Malayan Nature Society, Kuala Lumpur. (revised ed.)
5. Richarz, K. & Limbrunner, A. (1993). The world of bats, the flying goblins of the night. T.F.H. Pub., Inc.
6. Wells, D.R. (1999). The birds of the Thai-Malay Peninsular. Vol. I, Non-passerines. Academic Press, London.

On 9th June 2006, Tang Hung Bun captured an image of a duck perching atop a street lamp along Bukit Timah Road, near Raffles Town Club.

The white duck has a brown back and wing tips and a rusty band across its breast. Its legs, feet, bill and eyes are pinkish.

This duck is new to Singapore. KC Tsang helped identify it as Radjah Shelduck (Tadorna radjah), also known as Burdekin Duck, from the Northern Australian coast and parts of Indonesia.

For at least a year, if not longer, the duck can be seen in the Symphony and Eco Lakes of the Singapore Botanic Gardens. Apparently it has been wandering around the island.

Introduced as a free-ranging bird? Escapee?

Incidentally, the Radjah Shelduck is listed as a protected bird in all states of Australia.

Images by Tang (duck on street lamp) and KC (others).

On 21 March 2003, Chiu Sein Chiong, Ooi Beng Yean & Cheang Kum Seng successfully located a Black Eagle (Ictinaetus malayensis) nest containing a well-developed young (left). The nest was found in lower montane forest at about 1360 m asl at Pos Slim, Perak. As far as we are aware, this discovery constitutes the first nesting and breeding record for this species in Malaysia. The following is an account of the chain of events that led to this exciting discovery.

The sighting of a pair of Black Eagles in courting/pair-bonding flight above a ridge in Pos Slim, Perak on 26 January 2003 kindled a flicker of hope that the pair was either selecting a nest site or was already nesting. During a second visit to the same location on 12 February, a Black Eagle was observed carrying a forest rat which it dropped off behind some trees on the ridge. It re-emerged very quickly and glided away. Subsequently, a second Black Eagle emerged from the same ridge to confront a different pair of Black Eagles that were approaching. Later, on the same day, a Black Eagle was again observed dropping off a lizard at the ridge.

On the morning of 16 February, a Black Eagle was again seen carrying a lizard to the same line of trees on the ridge, dropping out of sight and reappearing soon after. By now we were quite positive that the Black Eagles were nesting on the ridge but the prospect of a tiring climb up the hill-cutting and then into the montane forest to look for a needle in the haystack was enough excuse to put off the search to another time. However, at the enthusiastic urging of the others, a party set out that same afternoon to find a way up to the ridge. The climbers successfully worked their way up the hill-cutting to the forest edge but decided against venturing further due to fading light. Now that the type of conditions and terrain were known, it set the stage for the planning of more climbs in search of the nest.

Our intended nest search plans were in disarray when suddenly access to Pos Selim for the general public was cut but thanks to the co-operation of the authorities we were given special permission to enter. On 9 March, one Black Eagle was again seen carrying a rodent back to the nest site. A second eagle appeared and glided into the nest location. From this we deduced that the Black Eagles had young in the nest. On 16 March a second nest search was organized. While a small group climbed up to the montane forest, the ground crew monitored the movements of the Black Eagles and provided feedback using walkie-talkies. Although the searchers occasionally caught glimpses of the eagles flying over, the thick canopy prevented them from seeing the flight direction of the eagles. The closed canopy and steep terrain did not help and we had problems with getting our orientation right. The search was called off as it was getting late and rain clouds gathered. However, the day’s efforts had not been a waste. The ground crew had observed a Black Eagle bringing food descend and ascend vertically within 2-3 seconds. This pinpointed the likely location of the nest and immediately motivated us to decide that another search be carried out within the next few days.

On 21 March, Ooi and Cheang started their climb at 10.30am while Chiu again provided ground support. Up to 11.50a.m. there was no sign of any Black Eagle but finally at 11.55am, one was seen heading towards the nest site. At 12.20pm, Ooi managed to “point” out his position in the forest to Chiu using a palm tree as a landmark. This indicated that Ooi was about 50 feet from the nest site. At 12.35pm, one of the Black Eagles flew out of the nest and joined the other Black Eagle that was performing flight displays. The first eagle turned back, perched and started calling. The second eagle then flew in to perch close to where Ooi was and then started to weave in and out of the forest. The behaviour of the Black Eagles was probably due to Ooi getting close to their nest. At 1.15pm, the walkie-talkie cackled again and the first words from Ooi were “EUREKA! Found the nest, one chick
inside!”

The nest was on a medium-sized tree, about 60 ft tall, growing on a very steep slope with its crown clear of smaller trees around it. The nest itself was lodged amongst the main branches, below the crown and near the center of the tree and was partly concealed by foliage and epiphytes. The nest was a compact mass of small twigs and branches, measuring about 2.5 ft wide and 2 ft deep.

The juvenile, seen with one of the adults, appeared to be about two-thirds as large but with a short tail (right). Overall, it was dark brown, with back and wing feathers quite developed but with some remnant down still attached to the feather tips, giving the back a speckled appearance. The head and neck area was almost bare of feathers, with the large ear opening clearly visible. The dark eye, with a whitish orbital ridge above, had a greyish-black orbital area around it, giving the face a sunken look, not unlike that of the head of a vulture. The bill was black with a light yellow cere and gape. The underside, including the breast and thighs, was still covered with downy feathers. These descriptions of the juvenile were based on digital images taken on the day the nest was located and also during two subsequent visits on 22 March and 23 March.

On a visit on 31 March, the nest was found empty. No Black Eagle adult or juvenile was seen in the vicinity during a two-hour vigil. Another visit on 8 April confirmed that the nest was empty. Again no Black Eagle or young was seen in the immediate area of the nest and nearby forest. At the time of writing, it is not known whether the young had fledged successfully as no flying juvenile has yet been sighted.

Note: Laurence Poh Soon Ping, Lim Kim Chye, Lim Swee Yian, Dr.Chan Kai Soon, Dr.Chan Ah Lak and Pamela Phang participated in the nest search leading to its discovery. Other contributors were Sharon Chan, Leow Kon Fah and Phang Chee Mun.

21 April 2003: 2nd Nest

In 26 October 2003, Chiu Sein Chiong and the late Laurence Poh Soon Ping observed a pair of Black Eagles breaking off branches to build a nest around 2km from the 1st nest site which had been cleared for hill slope stabilization work (left). The pair also exhibited courtship displays in flight. On 20 November, Chiu and Dr. Robert DeCandido saw one Black Eagle rearranging sticks in the large completed nest, no new branches were brought back.

On 21 December 2003, Chiu & Ooi Beng Yean observed the pair circling before perching and calling out. The pair then copulated. On 4 January 2004, Lim Kim Chye and Lim Swee Yian saw one Black Eagle gliding around the nest tree and incubation had not yet commenced.

On a visit on 8 February 2004, Chiu, Laurence Poh and Cheang Kum Seng confirmed that incubation was in progress and we also witnessed change of incubation duties. On 7 March one of the adults was seen frantically dive-bombing a Siamang which was trying to approach the nest. Incubation was still in progress on 16 March and by 28 March it was suspected that there was a small chick in the nest.

On 1 April 2004 Kim Chye saw one chick in white down and still wobbly. By 6 April the chick was left unattended for long periods, white down still extensive all over head and body but black/dark brown pin feathers visible on wings and tail, bill black with yellow cere.

The chick was last seen alive on 8 April (Kim Chye) and 11 April (Chiu) but on the next visit on 22 April, Kim Chye reported that the nest was empty and no adults or juvenile was seen in the vicinity. Another observation on 26 April (Chiu) confirmed no Black Eagles around the nest tree.

We were unable to confirm if the Juvenile had fledged but based on plumage of chick we think that it was too young to fledge and probably was predated.

Images by Ooi Beng Yean (eagle by nest) and Laurence Poh (eagle in flight, permission courtesy of Mrs Poh).

From the article:
Chiu, S.C. and Lim, K.C. 2003. The First Breeding Record of the Black Eagle Ictinaetus malayensis in Malaysia. Suara Enggang 11 (2):14-16.