In the earlier post on the prominent black pouch of the Blue-eared Barbet (Megalaima australis) by Adrian Lim a.k.a wmw998, there was a discussion of the pouch being used as a possible storage for food.

Adrian was adamant in his belief that the pouch was for vocalisation and not for food storage. He wrote, “I had watched the birds for days, and I can safely tell you the pouch wasn’t used for the purpose of holding food, like a hamster! At all times, I had observed the food to be delivered directly from the male’s beak, not regurgitated food.

“I strongly believe that the pouch was for sound production to attract the female (soft note, sounds exactly like blowing a football referee’s whistle lightly, one note at a time ) and perhaps to warn other males of its presence (the chiok chiok sound). I had seen the bird perching on a branch, making both sounds, both using the pouch. The soft sound, as I had mentioned earlier, was made in between feeding the female, when the female happened to be away ‘temporarily’, eg. flown away from the feeding perch because of disturbance. And if you look carefully, the entire breast and belly of the male bird sunk in whenever it made such sound, to inflate the pouch.

“Please check into my posting in NaturePixel a couple of months back… I had some photos of the same male doing the blowing and puffing thing.“

The images above and below show the sequence of pouch inflation. In the absence of food in the bill and a female around, it would seem that the pouch is more involved in vocalisation.

Adrian added, ”This bird comes to the tree near my balcony and blows nonstop, a few times a day. No other bird joins it…

“…I think all barbets, except the Brown, and possibly the Lineated, do the same blow job. So far, I have also captured the Golden-throated doing the same thing. Funny though, they do not open the beak while blowing.”

According to Short & Horne (2001): “Most barbets.. sing to proclaim and maintain a territory; since these species largely occur in pairs or social groups, the female is usually near or with her mate. …the basic form of the song is not elaborate in most barbets, in which a series of low-pitched ‘hoot’ or ‘hoop’ or ‘ooo’ notes are uttered perhaps ad nauseum, seemingly, as in some tinkerbirds and the Coppersmith Barbet.”

In another communication, Short & Horne (2002) state that “most barbets give a relatively low-pitched ‘hoot’, ‘hoop’ or ‘pop’ notes that may be repeated in short to long series as a song, uttered with the bill closed or nearly so.

“…Aggressive calls generally are noisy, and commonly include fast, chattery, squawky, honking, rattling and grating sounds, usually repeated in short to long phrases and often compounded, as in a squeaky grating or squeaky chatter.

“…the more hooping, popping or hooting songs seem ventriloquial, and may vary in volume simply as a result of the barbet turning its head as it sings.”

We will discuss the role of the pouch, or gular sac, in another post.

All images by Adrian Lim.

References:
1. Short, L. L. & Horne, J. F. M. (2001). Toucans, barbets and honeyguides: Ramphastidaer, Capitonidae and Indicatoridae. Oxford University Press.
2. Short, L. L. & Horne, J. F. M. (2002). Family Capitonidae (Barbets). Pp. 140-219 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 7. Jacamars to Woodpeckers. Barcelona: Lynx Editions.

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.

The Javan Myna (Acridotheres javanicus) that was passed on to me by Lin Yangchen on 21st February 2008 spent a quiet night in its cardboard box. It made soft chirping sounds when I opened the cover of the box the next morning.

Initially widening its gape reluctantly, it did so without persuasion as it was hungry. It was fed mashed bread in water and pieces of banana. Small lumps needed to be directed into the gape before the chick swallowed them. Pieces of mashed fish were also given. It made minimum sound when fed.

As it developed, the chick was more responsive, making more sounds and opening its bill when food was offered (left). It began to grab at the food offered when placed in the centre of the gape, rather than passively allowing the food to drop in.

Usually, it accepted two to three offerings of food at a time, after which it will not accept more. It needs to be fed regularly and often.

As it grew, it made more sounds and moved about inside the box. It also responded when I approached, making chirping sounds, asking to be fed.

Four days after rescue (X+4, X=21st February), the chick began to stand upright and hopped around a bit when places on the grassy ground. It was also seen preening its feathers along the sides of the belly.

The colour differential began to develop. The juvenal feathers around the nape became darker grey than those around the flanks (right top). The wings, other than those feathers showing white, were distinctly black.

On the morning of day X+5, the chick began to preen its wing feathers and scratched its head. It was also seen stretching its wings as well as flapping them.

This was the first time I noticed how it slept. Supporting itself on its tarsi and rump, it placed its head on one side of its shoulder, raised its lower eyelids to close the eyes and then went to sleep (right bottom). It also slept by resting its entire body on the ground, the head similarly touching the ground and wings slightly unfolded (right top). The legs were still not totally strong enough for the bird to stand most of the time.

On day X+6, the chick made louder noises in the morning from inside the box, obviously begging for food. It also flapped its wings vigorously. Unlike previously when anything that was placed into the throat was swallowed, this time the food offered, even when placed inside the throat, was first subjected to a vigorous shake of the head resulting in most being flicked away.

On day X+7, the chick was standing more, even hopping about more. With time the legs got stronger and it was able to stand most of the time. The image below (left), showing the chick supporting itself on its pair of tarsi, was taken on day X+5. That on the right, taken on day X+11, shows it standing upright.

The bird had the habit of turning around to defecate. This happened after taking a few mouthfuls of food. It would turn around, its back facing me, and defecate. Initially puzzled, I later realised that this is what it will do inside the nest.

The chick would be fed from outside the nest and the chick needs to turn around to force its faecal matters from its vent out of the nest. After all, it is not wise to pollute the nest as this will attract predators.

“On January 13th, 2008, John McGeehin, Shamla Subaraj and I spotted an albino Javan Myna (Acridotheres javanicus) at the main car park of Bukit Batok Nature Park.

“The time was about 5.30 pm and the bird was walking about a grass patch, searching for food. I managed to take a few photos. It was then that I noticed a “normal” Javan Myna foraging close-by. We observed the duo for a while and noticed that they were probably a pair as they kept fairly close to each other while walking around. Not too far away, another pair of “normal” Javan Mynas were also foraging in a similar fashion.

“Nearly a month later, on February 2nd, Huw Penry, Shamla Subaraj and I were about to leave the Bukit Batok car park, at 6.15 pm, when we noticed a flock of Javan Mynas flying across the road. With them was an albino myna, probably the same individual from early January.

“Although albino birds have been encountered from time to time, they usually seem to be on their own and not accepted by the others of their kind. As such, these observations were most interesting. Not only did this albino myna seems to have a normal mate, but it also seems to have been accepted by the rest as it was flying with the flock.”

On 21st February 2008, Lin Yangchen offered me a Javan Myna (Acridotheres javanicus) nestling that a colleague of his picked up near their office. This is my second nestling, the first was a Little Heron (Butorides striatus) that I looked after until it was ready for release.

Apparently the nestling must have been kicked out of the nest by its sibling, a common occurrence (above). Hatched naked and blind, as with all altrical young, the eyes of this nestling when picked up were open and wing feathers developing. So it cannot be newly hatched or even a few days old. Maybe a week or more?

The bird is covered with mostly black feathers, with patches of white feathers on the wings. However, when the wings are extended, the naked body becomes obvious, the pinkish skin showing prominently (left). There are no natal downs. All along the back is a narrow strip of black juvenal feathers. Along each side of the body is a similar strip of feathers.

There is a short tail, the developing feathers are only half emerged from their sheaths, the outer of which have white vanes and the rest black and white. On the rump, immediately in front of the tail is a yellow growth, the preen gland, also known as the uropygial gland (above). This secretes oil that the bird spreads over its feathers during preening, to prevent them from becoming brittle and probably to inhibit the growths of harmful microorganisms like fungi and lice. This gland is prominent in the half-naked chick and usually not at all obvious when all the feathers are in place.

The wing feathers are similarly incompletely free from their sheaths, about slightly less than half their lengths have emerged (left). The primaries and secondaries are all black. The primary coverts are white.

The light orange oral flanges are conspicuous. These are the temporary enlargements of the base of the bill, targets for the adults feeding the chick.

Immediately below the tail can be seen the cloacal opening, the vent, ringed with emerging pin feathers. The cloaca receives faeces from the large intestine, urine from the kidneys and eggs or sperms from the gonads. And it is though the vent that wastes are excreted.

The legs appear fully developed, with well-formed toes that come complete with claws. However, they are not strong enough to support the body. Thus the chick cannot stand upright but uses its heels and rump for support to sit upright (left). It moves with the heel and tarsus (that portion of the foot between the heel and the toes) flat on the ground.

The chick was not moving much and not making any sound at all. It weighed about 40 grams. But it did respond, opening its gape slightly, to offer of drops of water and even pieces of bread soaked in water. It even made soft chirps, indicating that all is well.

Images by YC.
.
.

On 23rd November 2007, Daniel Koh spotted a Grey Nightjar (Caprimulgus indicus), a rare passage migrant and winter visitor. The bird was perching on a large branch (left). Many birders came across the Grey on a branch, unlike the resident Large-tailed (Caprimulgus macrurus) that is usually seen on the ground. Being a perceptive birder-photographer, he noticed that the bird was sitting along the branch and not at right angle to it as with most birds. So he was curious to have a look at its feet.

As luck would have it, it was Chan Yoke Meng who managed to get a shot of the bird’s foot when it was scratching its head (below).

A nightjar’s feet are weak, as seen in the above image, as they are adapted for resting on the ground. The toes do not have the powerful grip of most other birds and presumably the bird has difficulty perching on slender branches. It is thus able to only perch on a large branch, and only sits along it.

However, this does not mean that the bird is clumsy on the ground. Many species can walk quite strongly, especially the chicks. And many occasionally feed on the ground. The toes are partly webbed and the middle toe is pectinate, as seen in herons. This is possibly used to remove parasites and straightening out the rictal bristles during preening.

Nightjars are nocturnal birds, roosting during the daylight hours. And it is during such hours that they are most vulnerable to predators. This is where their cryptic plumage comes into play, to avoid detection during the day when they are roosting.

The head appears large in relation to the body. The bill is small and appears weak. The gape is enormous and lined with long, extremely tactile, rictal bristles. These bristles are modified contour feathers whose barbs are absent. Such are the adaptations for aerial feeding.

The eyes are large and laterally placed. At night they respond to light by shining, an adaptation to improve the vision during dusk and dawn as well as during the night when the moon is absent from the sky.

Many have conspicuous white patches in the primary as well as outer-tail feathers, as seen in the Grey above, when it was stretching its wings. When the bird is resting, these white patches are never seen, becoming obvious only when in flight. These markings come into play during territorial aggression, courtship and defence displays as well as to distract predators at the nest site.

When approached, the bird may flatten itself to reduce shadow and outline, as well as close the eyes (see top image). Such behaviour provides total camouflage and it is literally unseen, especially on the ground, until you are very near, when the bird suddenly takes off with a noisy flutter.

The bird is an extremely strong flier, being provided with long, slender wings.

Top image by Daniel, others by Chan Yoke Meng.