Being a wildlife officer attached to the Department of Wildlife Conservation in Sri Lanka for well over thirty years, I would see numerous experiences I had in the field, to share with the others. It may be interesting to someone who care for wildlife and nature.
This is based on my book titled 'Lost Trails in Yala - East', edited by Lalith Seneviratna and published in 2010 by Dayawansa Jayakody.
Over their evolutionary journey primates of all animals developed comparatively the most developed brain. However, they possess inherent a...
Sunday, October 9, 2011
Being a wildlife reserve famous through the ages for birds, the word ‘Kumana’ instantly paints in one’s mind a picture of a bird paradise. As described earlier ‘Kumana Villu’ is a low lying swamp near the estuary of the Kumbukkan Oya river. The ring of mangrove strands in the middle of the villu creates a unique and safe environment for the nesting of aquatic birds.
Thousands of birds belonging to a variety of species build their nests in the villu and feed the nestlings during the months of June and July. Formation of separate colonies belonging to each species is a special facet observed here.
As most visitors to Kumana were avid birders and bird lovers, officers stationed in Yala East were obliged to learn about birds that led to most of them having the ability to identify them at sight.
Among the prominent species of birds to nest in the villu include, Painted Stork, Spot Billed Pelican, Cormorant and Darter. Painted Stork is the most colourful of them while the pelican is pale in colour. The pelican has the skin forming a ‘sack’ under the bill which helps the bird to regulate body heat and gives it a special look. Cormorant and darter are master divers and ascend to the surface to swallow their prey that is caught underwater. White Egrets are amongst the most common species of birds in the villu. Spoonbill and Black Headed Ibis both have uniquely formed bills. Purple Heron and Grey Heron are some of the other common species of birds nesting there.
During the nesting season adult birds bring sticks one by one from the nearby forest to pack together and build their nests. The hatchlings of most species do not resemble their parents. Those of the cormorant that is glossy dark in colour in adulthood, have a pure white plumage. Hatchlings take sometime to develop the colourful plumage and resembles their adults.
Adults have to provide a continuous supply of food to the greedy hatchlings. They return to the nests after repeated journeys to the nearby tanks and lagoons and regurgitate the food to feed the quarrelling hatchlings. Quarrelling makes the hatchlings develop the strength to overpower the weaker siblings and get the lion share of the feed. As a result, weak members may die of starvation.
Sometimes the parent birds have to travel long distances to reach feeding grounds. Birds such as Painted Stork, Open-billed Stork and Pelican employ an interesting strategy to travel long distances with the least amount of energy. As the sun rays warm the ground in the morning, it in turn makes the lower layers of air warm and light. This warm and light air rises into the sky in the form of convection currents. The birds soar into the sky in a circular movement by spreading their wings and latching onto these currents. Once they reach adequate height that gives them a commanding view, they fly towards the feeding grounds.
Painted storks start feeding early morning in the shallow waters of a lagoon or a tank. The strategy adopted to catch the prey is driving the fish to come under the shade of its unfolded wing by stirring the mud with its legs. The fish, frogs and the crabs unsuspectingly take refuge such, only to be devoured by the bird.
White Egret and Herron wade in the shallow water and stand still patiently until prey comes within the reach of their bill. It is rarely that a fish escapes the darting sharp bill. If a fish caught is too big, it is brought ashore to be beaten to death before being swallowed holding the head down.
The Spoonbill wading in shallow water stirs the mud sideways with its spoon shaped flat bill to catch the prey. They do this as a flock moving in a line forming a front for better results. The Open-billed Stork gets its name because of the gap developed between the two mandibles of the bill when closed, as it grows into adulthood. It feeds mostly on molluscs such as snails and oysters, opening them with its strong bill.
Cormorants and Darters show adaptations to aquatic life with their ability to dive deep in water. Fish caught underwater are tossed in the air and snapped at to swallow head down first. It will be rare for a fish to slide out and escape from the serrated edges of the mandibles. Once I observed a flock of about three thousand cormorants working together to catch prey in the Parakrama Samudra reservoir at Polonnaruwa. The flock looked like a huge wheel rolling in water. Birds at the rear end of the flock took off and flew to the front, to dive repeatedly and re-emerge from the rear - this keeps repeating while the virtual wheel formed by the flock keeps turning and moving forward. It was seen that other birds such as pelicans and terns too got into the flock and made good use of the opportunity.
Sometimes, birds belonging to different species and living at different levels of the forest canopy but sharing a common feeding habit can be seen forming a union and foraging for insects by moving around together. Insects escaping from birds foraging at the ground level would become prey to birds living in the upper layers of the forest. This symbiosis collectively benefits all bird communities of the forest by the maximum use of available resources.
Although the villu is a relatively safe haven for nesting sometimes predators such as monitors, serpents, eagles and kites would be smart enough to raid a nest and snatch an egg or a chick. The youngsters of Kumana too at times evade the wildlife officers stationed there and wade across the villu to steal eggs so that they could relish an omelette.
Apart from the villu, Kumana tank too is an ideal home for aquatic birds. Pheasant Tailed Jacana the call of which resembles that of a cat is a beautiful bird with a long tail. Its long toes enable it to be steady on the Nelum lotus leaves while walking or briskly whisking away its chicks by hiding them under the wings when surprised by a predator. Purple Swamp Hen is another colourful bird found among the Nelum leaves. Its dark purple plumage and the bright red wattle help to quickly recognize it.
Migration of birds starts with the onset of the north-east monsoon winds in September or October. Migration of birds that normally inhabit the upper parts of northern hemisphere such as Siberia and Europe to the tropical countries close to the equator is caused by the scarcity of food and extremely cold weather experienced in the winter. This amazing journey taking place across countries and continents is sometimes a continuous flight of thousands of kilometres. This arduous feat needs lots of energy which they stock in the form of fat deposits in their bodies by consuming excess food preceding the start of the migration. Birds have a wonderful inherent ability to find their designated migratory track. It is believed that their sensory perceptions allow them to follow earth’s magnetic field and patterns of the stars.
In their final part of the journey these birds migrate across the Indian sub-continent and enter the island through northern and north western coasts. Whilst the forest birds distribute themselves inland, most of the aquatic birds move along the coastal belt, southwards. The chain of lagoons along the coast of Yala East is an ideal habitat for them. The shallow lagoons and adjacent mud flats are rich feeding grounds for these birds that feed on molluscs, crabs and other small aquatic creatures. During the migratory season a number of sandpiper and plover species can be seen moving about in the lagoons in large flocks.
Though these aquatic birds do not bear colourful plumages as the forest birds they nevertheless have a variety of interesting physical features. Especially the shape of the bill differs from each other to suit their respective feeding habits. Whilst some of the bird species have a short bill to feed on small creatures such as molluscs on the surface, some have a long thin bill to pull a crab out of its deep cavity. The Whimbrel and other curlews almost always found on the beach have such curved elongated bills.
The Flamingo is a large rare visitor to the lagoons in and around Yala East. This beautiful bird which is about five feet in height can be distinguished from far by its long neck and legs. The ultimate destination of the flamingo that arrives in flocks of hundreds is Bundala Lagoon, near Hambantota. Once I observed a flock of about five hundred taking a short break in Panakala lagoon near Panama, while on their way to Bundala. Flocks of thousands of flamingos wading in the Bundala lagoon is a common sight during the migratory season.
Evolutionary strategy has favoured different species of birds to develop the palate for different food types occurring in different habitats and thereby reduced the competition for food and space.
Many migratory tern and gull species can be observed hovering along the coast and the lagoons. They fly over the water gazing at the surface and dash into the water as soon as a fish appears. There is another group of birds confined to grasslands around lagoons and other water bodies. They feed on grasshoppers, annelids and other small creatures and have varied and interesting patterns of behaviour.
Red-wattled Lapwing which sings by repeating the question “did he do it?” is a common bird in open grasslands. Yellow-wattled Lapwing which differs only by the colour of the wattle is not as a common bird. Lapwings do not bother to build elaborate nests and lay eggs on a dry cow dung pat on the ground. The colour pattern of the egg shell is camouflaged such that it cannot be distinguished even at very close range. During the breeding season when the eggs or the chicks are there in the nest, they do not hesitate to challenge any predator coming close. On such occasions their high pitched call is raised while flying in rapid wavering patterns into the sky and this does not cease until the danger is no more.
‘Broken wing’ posture is another strategy used by lapwings to get rid of predators. It draws the attention of the predator away from the nest by running away pretending that one of its wings is broken. There are a number of other species of birds which adopt the broken wing posture.
The small common bird species on the grasslands are larks and pipits. Their plumages which are not that colourful help them to escape the attention of predators in their open habitat. These small birds call constantly and make the surroundings come alive. The Bush Lark which parachutes down is quite a versatile species.
Forest birds have more colourful and attractive plumages. They confine themselves to different forest canopies at different heights and have food preferences different to each other. Dark plumages help them to camouflage in the backdrop of the dark colours of the forest and escape the attention of predators.
Indian Pitta is undoubtedly a beautiful bird and spends most of its time turning debris on the ground. It is a common bird that migrates from India and evenly spreads out all over the island. One of the rare migrants we observed almost every year near the staff quarters at Okanda was the Orange-headed Ground Thrush. This beautiful bird with a reddish-yellow head and under parts can be seen foraging on the ground and in the forest undergrowth.
Woodpeckers hang on tree trunks and remove the bark with its chisel like bill to feed on small creatures found underneath the bark. Among them the Rufous Woodpecker has a peculiar behaviour pattern. It lays its eggs in a cavity built in an ant nest about the size of a football. The symbiosis existing between a bird and an ant is interesting.
Of the birds living in the upper canopy of the forest the Hornbill has an unusual habit that deserves some sympathy. In preparation for laying eggs the female bird enters a tree hollow and leaving only a small orifice to put the bill out for feeding, closes its opening with a cement made out of its own droppings. Thereafter, the eggs are laid and incubated with the female being a virtual prisoner depended on the food fed by the male bird through the opening. During the incubation period the female sheds all its feathers and develops a new plumage. After the eggs are hatched it comes out breaking the cement and starts feeding the chicks with the help of the male. Of the two species of hornbill found in Sri Lanka, the Malabar Pied Hornbill looks rather distinctive with its large protrusion on the bill.
Every evening, a large flock of Malabar Pied Hornbills would come to Okanda lagoon to roost in the mangrove forest therein. During my stay at Okanda I was not awakened by the usual musical calls of the myriad of birds but it was the sharp call of the hornbills which came to the huge Palu tree near my living quarters that put me out of my dreams. Each morning they annoyed me with their irritating screech which resembles the cry raised by someone being choked.
While some of the bird species distribute over all types of habitats in the forest, certain species confine themselves only to specific habitats. The Red-faced Malkoha is one such rare species that confines itself to riverine forests. So far, I have seen this beautiful bird only twice, once at Gal amuna along the Kumbukkan Oya and once at Karanda Oya on the way back from Bakmitiyawa. Sighting of this shy bird endemic to Sri Lanka is a reward for a keen bird watcher.
There are number of nocturnal birds that can be seen while patrolling the park at night. The Nightjar, one of the commonest among them is found perched on the dusty sand layer of the road. Suddenly, this small bird with a large mouth jumps into the sky and snatches an insect flying close to it and returns to its original spot.
Being nocturnal carnivores owls have peculiar patterns of behaviour. Any creature from a small lizard to a hare would be an easy prey for the sturdy owl. Its hunting ability is supported by large eyes which can see clearly even in the dark, sharp hearing, a well developed bunch of claws and a strong pair of large wings. An interesting feeding habit of the owl is that any food that is indigestible such as bones, hair, and feathers, are compressed and regurgitated as compact pellets. Bee Eaters too have the habit of ejecting the undigested parts of the food back through the mouth.
Eagles and the kites are the masters of the sky. Eagles are capable of gliding over their territory spreading their strong and wide wings and then dashing and snatching a small mammal, a serpent or even a fish at sight, with its long sharp claws. A prey caught with the four claws resembling steel hooks wouldn’t have the least chance of escaping. Eagle species have food habits different to each other.
The Black Eagle which is a fairly rare bird mostly raids the nests of other birds to feed on their eggs and chicks. It prefers to live in the vicinity of mountains and escarpments and when found in the low country it is frequently observed along foothills. The crest on the head helps to distinguish the Changeable Hawk Eagle from other species of eagles. While it spends most of its time on the branch of a tree watching around for prey, it can at times be seen at the edge of a puddle having a bath. The Hawk Eagle has the skill and the strength to kill a prey even bigger than it. Once at Kumana I came across a Malabar Pied Hornbill killed by a Hawk Eagle.
It was at Lunugamvehera that I saw the real ferocity of the Hawk Eagle. That afternoon I was walking along a foot path across the catchment area of Lunugamvehera reservoir with Mr. Shirley Perera. With the water level of the reservoir receding small puddles were left here and there on the exposed grassland. Suddenly, we noticed a Hawk Eagle standing in a small puddle close to our trail. With water seemingly up to its knees the bird was turning its head and seemed disturbed. I went off the trail sneakily with the intention of getting closer without disturbing the bird. I wanted to take a photograph taking cover behind a large dead tree standing near the puddle. But, however careful I was the bird noticed me by the time I reached the spot. As I raised the camera it took off before I could snatch a photo. What caught our eye next was most unexpected. A White Egret popped out of the water at the spot where the eagle was standing. Having been drowned forcefully by the eagle the egret was semi conscious and was wavering and struggling to get out of the water. We did not disturb the helpless bird and moved away. It appears that having caught a prey too big to subdue the eagle thought of drowning it.
The staple food of most common of eagles, the Serpent Eagle, as its name suggests are serpents. During the breeding season it rises high up into the sky with the morning convections currants and performs acrobatics before mating. The White-bellied Sea Eagle whose under parts are snow white is always seen in the vicinity of the sea or a large reservoir. Their large, wide and strong wings help them to fly close to the surface of the water and snatch a swimming fish. They also have the habit of snatching a prey possessed by other eagles.
There are countless aspects of the forest which bring pleasure to one’s mind. Watching birds moving about in the trees and branches is foremost among them. It does not take undue time or effort. It does not need one to be too selective about the place. Just developing the habit of looking at a flying or playing bird twice will be the beginning of a bird watcher. Birds with their innumerable displays are capable of filling our life with great joy.
"Who's there? Who's there? Why have you come?"
The shamas sang in their green abode
They had for generations known,
While the hunter trod the jungle road.
"What bird is it that sings so sweet?"
The hunter asked his native guide.
"The meecha, Sir; it's black and white:
The Kala meecha," he replied.
They walked along while the singers piped,
And mellow the changeful notes they blew.
"Show me the bird," the hunter said-
But ever the bird evading flew.
"Who's there? Who's there? Whom do you seek " Came from the bough the fay retort:
From this bough now, from that anon-
A glimpse at last - a gun's report!
The shama's dead on the mossy grass,
They lift it, and speak of the sweet song made
By the limber form and the slender beak
Of him that piped in the leafy shade.
They reach their camp: the shama's sketched,
And skinned and brained- “Where's the goodly bird?”