Wednesday, November 9, 2011
Acrobats of the skies
Posted on October 30, 2011, Sunday The Borneo Post
THE acrobats of the skies, in their chase of the next meal, leave no rollercoaster-like flying moves undone. They loop, swirl, do figure eights and even figure 16s in their quest for food. Swifts and swiftlets, probably the fastest birds alive, are able to reach jaw-dropping speeds of 110km per hour. As their Malay name layang-layang – the kites of the sky – indicates, swifts and swiftlets are helpless if they land on the ground. Their weak legs and feet make it impossible to take off.
However, when they rest they hang on with strong claws and then they simply free fall into space when taking off. Borneo hosts 10 of the 99 species of the Apodicae family. Despite sharing their Malay name, layang-layang, a hunger for insects and unbelievable flying skills with swallows, they are not related. Swallows are members of the Artamidae family that includes martins and woodswallows.
Swifts, which communicate generally with a series of squeaks, are hugely beneficial to man, as they eat mosquitoes, bees, wasps, flying termites and other winged insects. These birds, in the past, nested in shady overhanging rocks or at cave entrances, which received light. Now they nest on man-made structures such as under bridges and overhanging roofs.
House swifts (Apus nipalensis) are common in towns and cities. They nest in clumps under the eaves of old buildings with the female laying up to three eggs. The chicks hop nests in order to escape parasites. Swiftlets are a subgroup composed of non-echoing and echo locating birds. One of the most common birds in Borneo’s skies is the non-echo locating glossy swiftlet (Collocalia esculenta), which ranges from the low coasts to the mountains. Its nests, made of long grass, are built in small colonies along the ledges of buildings and shady multi-storey car parks, where it is considered a pest. However, it is a beneficial bird as it eats mosquitoes. The nest is of little value in the multi-million bird’s nest industry, but the birds are used by farmers as surrogate parents for the valuable edible-nest swiftlets.
The exotic nests of edible-nest swiftlets (Aerodramus fuciphagus), sought in Borneo by Chinese traders from the 1400s, are believed to be beneficial to the entire body. This traditional belief is not supported by science. Despite this, the nests remain a very high value crop for either owners of natural caves or farmers who convert existing buildings or build specially designed ones to mimic the darkness and the ledges of the limestone caves that tunnel through many parts of Sarawak.
Edible-nest swiflets build nests with their saliva up to five times a year and normally lay two eggs. These nests, unlike the black-nest swiftlet (Aerodramus maximus), do not contain feathers or plant material. The value of the nest of the black-nest swiftlet is about 20 per cent that of the edible-nest swiftlet. The black-nest swiftlet nests in colonies and generally lays a single egg.
Predators, which include snakes, owls, eagles and civets, can be seen around the mouths of the caves. The dramatic handover between bats and swiftlets is best seen at dawn or dusk. At dusk, funnel clouds of bats disperse quickly to escape circling airborne predators including the bat hawk (Machaeramphus alcinus). This common hawk, which is normally active at dusk when the bats leave their roosts, catches them on the wing, swallows them whole and can consume up to 14 bats a night. In addition, it also catches swiftlets and other birds.
The swiftlets that build edible nests evoke great interest in academic and business circles. The sustainable harvesting and conservation of these swiftlets in Sarawak was the PhD project for Dr Lim Chan Koon. Lim lectured in Universiti Malaysia Sarawak (Unimas) before retiring and venturing into the raising and trading of the nest of these birds.
Today (Oct 30), Lim will present a lecture on these fascinating birds at the Borneo Highlands Resort as part of the Sarawak Bird Race 2011. This lecture is just one of the many planned activities at the Borneo Highlands Resort in addition to the flagging off of the half-day race for the second day of the Sarawak Bird Race 2011. Other activities, including programmes for children, guided jungle walks and photography exhibition, offer exciting Sunday activities for all members of the family. No doubt it will be exciting for the bird racers, but there is much to do for those of you who want to learn about and touch nature.