The Whiskered Treeswift (Hemiprocne comata) is distinctive in its white facial stripes. It is a forest species and resident in Malaysia. In Singapore it is a rare, non-breeding visitor, although it used to be a fairly common resident before.

Mark Chua a.k.a cajuka managed to document the intimate moments of a pair of Whiskered Treeswifts that ended in copulation.

The image on the left shows the male with his chestnut ear-coverts that is lacking in the female on his left.

It appears that very little is known of the breeding behaviour of this species and every little observation helps to increase our knowledge of this bird.

The nest is a half-saucer of feathers and saliva attached to a thin branch. A single egg is laid. Both the adults incubate the egg and tend to the young.

The images above and below show the male in the process of mounting the female to effect cloacal contact that lasts only a few seconds.

An earlier post gives the nesting behaviour of the Grey-rumped Treeswift (Hemiprocne longipennis).

All images by Mark Chua.

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.

Bee-eaters hunt from an exposed perch, waiting for insects to fly by. Once an insect is spotted, it flies after it and simply picks it out of the air. The pair of slender and sharp pointed mandibles that make up the bill function like a pair of highly efficient forceps.

The images above show the Blue-tailed Bee-eater (Merops philippinus) manipulating a dragonfly after catching and thrashing it. Clamped at the tip of its bill (left), the bird deftly tossed the subdued insect to reposition it for swallowing (right).

In the case of the Blue-throated Bee-eater (M. viridis) that has caught what looks like a wasp and a moth, the prey is similarly treated (above).

When a venomous bee is caught, as in the case of the Rainbow Bee-eater (M. ornatus) of Australia, the prey needs to be rubbed against the perch to remove the sting and the venom (above).

The images above show the Rainbow Bee-eater with a beetle (left) and a cicada (right) in its bill. Again, these insects need to be subdued before swallowing.

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.

All images by Dr Eric Tan.

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.

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.

I was trimming my starfruit tree (Averrhoa carambola) to remove the branches that were infringing on to my neighbour’s airspace. When collecting the branches, I was surprised to find a small nest attached to one of the end branches. So the nest was constructed high up the tree.

It was a smallish, oval nest, 14 x 8 cm, had a round opening 4 x 4 cm near the top (left). It was an untidy structure, with fibres sticking out all over the surface, looking like a mass of dried plant matters stuck to the branch.

The nest was firmly attached tied to the branch with masses of fibres. The round opening was lined with a defined rim of twisted fibres forming a distinct rim.

The fibres were carefully removed, identified and counted. Most of the fibres came from banana (Musa) and palms, making a total of 637 pieces, the longest being 31 cm. There were also 4 raffia strands and a single grass inflorescence branch. Loose lalang grass (Imperata cylindrical) floss scattered about the inner lining of the nest. There were also a few pieces of what looked like yellow spider cocoon silk, not specifically used to bind the fibres.

The Common Tailorbird (Orthotomus sutorius) has always been around the tree, foraging for insects, mostly ants. So the nest was most probably that of the tailorbird. The bird is about 11-13 cm in length and appears to fit the nest.

Also, earlier postings of Common Tailorbirds’ nests appear to be of similar size and shape. However, they were always built inside one to a few leaves stitched together like leaves of simpoh air (Dillenia suffruticosa), ginger plant or garden creeper.

Can it be that this nest is incomplete? And that when completed one or more larger leaves (taken from somewhere else) would be incorporated?

The African Fish-eagle (Haliaeetus vocifer) is confined to Africa and seen near most waterways south of the Sahara. It feeds mainly on fish, with each pair defending a relatively small territory. Perched high on a tree, it regularly belts out a gull-like laugh to keep in contact with its mate and to warn off intruding fish-eagles.

Willis was at Lake Baringo in Kenya recently when he documented an African Fish-eagle’s dramatic flight from its perch to catch a lure fish in the water - HERE: 1 and 2.

This drama is being played regularly for the benefit of tourists. The local guide stuffs a fish with balsa wood to keep it afloat. He then throws the fish into the water and whistles loudly to the eagle. Obviously the bird is used to being fed this way and responds to the call.

All you need do is sit back with your camera ready and shoot your multiple sequential shots as the fish-eagle zooms in.

Once the eagle spots the fish, it lunges from its perch and swoops down low over the water (above). The sight of this large raptor sailing down with its prominent white head flanked by a pair of huge black wings that span some 2 metres is a stunning sight.

When in flight, the raptor has its feet stretched back and the toed tightly clutched. As it nears the water surface, it lowers its pair of feet and un-clutches all eight toes to reveal the eight long, curved and sharply pointed claws (above).

Once the prey is targeted, the bird plucks it from the water surface, gripped tightly within the grasp of one set of talons, and flies off (above).

The takeoff is preceded by the upstroke of its pair of huge wings (above) before the powerful down stroke that easily gets it airborne again (below). Subsequent flapping of its powerful wings takes the bird back to its perch or to dry land to enjoy its meal.

During the upstroke, the resulting air pressure forces the primaries feathers to be twisted open, resulting in less resistance to the air. Once the wings are fully raised (above), the downstroke causes air pressure to push the broader inner vane of the primaries up against the outer vane of the feather over it (below). This produces an unbroken surface, thus the resulting lift (bottom).

The entire drama unfolds within a brief two seconds and only a fast-action camera can document the sequence shots that are shown here.

All images by Willis.

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.