The Common Coot (Fulica atra) is a large bird that is generally quarrelsome. The charcoal plumage and flashy bill shield make it easy to recognise. The image above was taken by KC Tsang when he visited the London Wetland Centre in June 2008.

Found frequently in still or slow-moving freshwaters, the coot is a fully aquatic bird. It takes to the air rather reluctantly but they are strong fliers, compared to others in the family.

An unusual adaptation to its life in water is the large, scalloped toes (left top). These enlarged lateral lobes provide for efficient swimming. On land, the bird appears clumsy when moving around.

The lower image on the left shows the foot of the American Coot (F. americana), with the lobes folding when the foot is moved forward so that they will not cause drag. The lobes will fold out when traction is needed with backward movement.

Coots used to be popularly eaten in Britain at one time. Traditional coot shoots were once organized at large wetlands where huge winter flocks were common. And large numbers were shot for sport and food.

Richard Carden wrote: “Coming from the UK where coots are incredibly common and having lived in HK & Japan where coots are not uncommon, I was surprised that they are such a rare bird in this part of the world

“This was highlighted to me a couple of years ago in Bali. I was birding with Victor Mason, an infamous character, author of at least two Bali bird books and founder of Bali bird walks which has been operating for at least 30 years. We were searching for white browed crake when my girlfriend Kaori shouted that she had found one, she pointed to the middle of the lake where there was a very obvious coot paddling around. Calming her down and telling her she had not found our target bird it was just ‘O-ban’, the Japanese name for common coot, I shouted over to Victor, false alarm, just a common coot. Without shifting his gaze from the lake edge and the crake search Victor said impossible there are no coots in Bali. There are now I said, at least eight of them ! Victor nearly fell in the lake, it was his first new bird for Bali in more than 10 years. Last recorded in Bali in 1953 I believe and only a couple of other times in the last century

“The moral of the story I guess is that one of the things that makes our shared hobby so interesting is you never know what will turn up and when.

“Hope Kaori can find us some coots in Singapore.”

Well, there was a confirmed sighting of the coot in 1940 and two others in the 1980s. These, no doubt were rare vagrants. None have been seen since.

Images of Common Coot by KC Tsang, that of American Coot by Joyce Tan of Palo Alto, California, US.

Jonathan has been monitoring the White-winged Tern (Chlidonias leucopterus) at Kranji since 2005.

In that early period when he was new to birds, he was rather puzzled by the “chocolate chip” tern he photographed and had difficulty getting it identified (above). He now knows that it is a White-winged dressed in a transitional plumage.

The White-winged, also known as White-winged Black Tern, breeds in Siberia. It winters south, moving down the Malay Peninsula to Singapore and beyond to as far as Australia.

In Singapore, it is possible to see the bird both in its non-breeding (above) and breeding plumages (below). The image below shows the breeding plumage, although “not quite though, judging from the white flecks on the head” – according to our bird specialist R Subaraj. Similarly, the “chocolate chip” bird at the top shows early transitional stage, as only some black feathers have developed.

Adds Subaraj: “White-winged Terns usually start arriving as migrants in September. They occur in numbers, particularly during passage, in coastal and offshore areas (and freshwater too). Numbers have declined over the years due to a reduction in foraging areas around our coastlines; such as the original Sg. Serangoon estuary where pig swill would empty out of the Sg Serangoon Kecil from the pig farms and this would attract hundreds of terns.

“Northbound return passage is often late in April/May and during that latter period is when you may have more birds in transitional or near-breeding plumage, as they moult in preparation for their return to their breeding grounds in the north.”

All images by Dr Jonathan Cheah Weng Kwong.

bklim photographed an adult White-throated Kingfisher (Halcyon smyrnensis) showing its brilliant colourful plumage – dark chestnut, blue and white. In addition, it has a red bill, dark brown iris, red orbital skin and legs. The female may have a slightly paler head and belly while the juvenile’s plumage is slightly duller. Whatever the sex or age, the bird is a spectacular specimen, guaranteed to impress anyone.

There is a popular misconception that the brilliance of the kingfishers’ colours is dependent on the angle of light, a result of iridescence. But iridescence does not come into play here, nor are the colours a direct result of the pigments.

What are responsible are the microscopic structures of the feather.

The mature feather covering is made up of a hard protein sheath of keratin. Just below this sheath is a layer of keratin cells filled with tiny pockets of air. As white light strikes the feather, the short wavelengths are scattered by the air pockets. As shades of blue (blue, indigo and violet) have the shortest wavelengths, they are scattered the most and in all direction. Thus we see the blue from any angle.

Just below the layer of cells containing the light scattering air pockets are melanin, pigments that absorb most of the longer wavelengths of light. This creates a dark background, thus intensifying the blue we see.

Other non-iridescent colours besides blue are also produced structurally. When the light-scattering air pockets are a bit bigger (bigger than the wavelength of blue light), the result is green (since blue is no longer scattered, and green wavelengths are now scattered the most), as in some parrots.

With even larger air pockets, no wavelengths are scattered, but all are reflected, producing white light and thus plumage that we perceive as white; white does not exist as a pigment in birds.

All images by bklim.

Reference:
Clark, G. A. Jr. (2004). [‘Form and function: The external bird.’]. Pp. 3.1-3.70 in Podulka, S., Rohrbaugh, R.W. Jr & Bonney, R. (eds.) Handbook of bird biology. Ithaca, NY: The Cornell Lab of Ornithology.

This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.

According to the literature, the prominent black sac seen in the Blue-eared Barbet (Megalaima australis) is a gular sac, also called vocal sac. See earlier posts 1, 2 and 3.

Birds produce most of their sounds with their syrinx, the sound producing organ sited where the windpipe divides into two. What is less known is that there are secondary acoustic structures that modify the sounds produced by the syrinx – whether to spread, amplify or reverberate. One of these is the vocal sac, prominent and exaggerated in some species.

According to Dantzker & Bradbury (2006), the bare vocal or gular sacs seen in the North American grouse and the Neotropical cotingas are inflated only in acoustic display. As most of these sacs are brightly coloured, they are probably also involved in visual signaling. The pan-tropical frigatebirds (below left) and two storks, the Old World Marabou (Leptoptilos crumeniferus) (below right) and New World Jabiru (Jabiru mycteria), also inflate their necks and vocalise, but not always at the same time.

In the above species, the sacs are often held fully inflated for lengthy periods in a strictly visual display and only used occasionally in sound production.

Three other groups have vocal sacs that are equally impressive but not devoid of feathers. Perhaps the most striking is the kakapo (Strigops habroptilus), an endangered flightless parrot from New Zealand that seems to inflate its whole body when booming. Many medium to large bustards, like the Kori Bustard (Ardeotis kori) (below left) inflate sacs that are often covered in elaborate feathering; and some but not all inflating bustard species vocalise while inflated (Collar, 1996; Dantzker & Bradbury, 2006).

According to Johnsgard (1983), certain calls among yearling crowned cranes involve the inflation of the gular sac. This is thought to serve as a resonator that may provide increased carrying power. In the Australian Crane (Grus rubicundus), the gular sac of the male is inflated during display and possibly helps to resonate low-frequency sounds. The Grey Crowned Crane (Balearica gegulorum) of Africa is shown above (right).

Strangely, there is no mention of barbets having gular sacs, not even in the most recent monographs of these birds. It is now obvious that the Blue-eared Barbet’s black sac plays a role in vocalisation, possibly also in fruit storage. And according to Adrian, other species of barbets also have these sacs. Obviously, there is much to be learnt about gular sacs and barbets. Happily, bird photographers like Adrian are currently at the forefront of this investigation.

References:
1. Collar, N. J. (1996). Family Otididae (Bustards). Pp. 240-275 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. Handbook of the birds of the world. Vol. 3. Hoatzin to Auks. Barcelona: Lynx Editions.
2. Dantzker, M. S. & Bradbury, J. W. (2006). Vocal sacs and their role in avian acoustic display. Acta Zoologica Sinica (Suppl.) 52:486-488.
3. Johnsgard, P. J. (1983). The cranes of the world. Bloomington: Indiana University Press.
4. Short, L. L. & Horne, J. F. M. (2001). Toucans, barbets and honeyguides: Ramphastidaer, Capitonidae and Indicatoridae. Oxford University Press.
5. 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.

Image of barbet by Adrian Lim, others by YC.

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 NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.