Friday 25 November 2016
Thursday 24 November 2016
23-11-2016 INLE LAKE, MYANMAR - BLACK SHOULDERED KITE (Genus Elanus)
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The Black-winged kite (Elanus caeruleus) is a long-winged raptor best known for its habit of hovering over open grasslands in the manner of the much smaller kestrels. Black-winged kites are well adapted to utilize periodic upsurges in rodent populations and can raise multiple broods in a single year, unlike most birds of prey.
The Black-winged kite is predominantly grey or white with black shoulder patches, wing tips, and eye stripe. Its long falcon-like wings extend beyond the tail when the bird is perched. In flight, the short and square tail is visible and it is not forked as in the typical kites of the genus Milvus. When perched, often on roadside wires, it often adjusts its wings and jerks its tail up and down as if to balance itself. The male and the female look similar. Their large forward-facing eyes placed under a bony shelf that shades them is distinctive; their velvety plumage and zygodactyl feet are characters shared with owls and the genus has been considered as a basal group within the Accipitridae. The inner vanes of the feathers have velvety barbules.
Black-winged kites are found in sub-Saharan Africa and tropical Asia, but they also have a foothold within Europe in Spain and Portugal. Their range expands in southern Europe and possibly in West Asia. Black-winged kites are not migratory, but perform movements in response to weather and food availability. They are said to be winter visitors in some parts of their range such as the Western Ghats. Black-winged kites are primarily birds of open land and semi-deserts. They are mainly seen on plains, and steppes and sometimes occur on grassy slopes of hills in the higher elevation regions of Asia.
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Black-winged kites are diurnal birds. They are usually seen singly or in pairs but at night they roost communally with groups of 15 to 35 (larger numbers in Europe) converging at a large leafy tree. They usually hunt flying slowly like harriers, but they will also hover like kestrels. On rare occasions, they can hunt prey in flight. Perches are used for hunting and for feeding but large prey may sometimes be handled on the ground. In southern Africa, they favor roadside verges for foraging. Black-winged kites are extremely silent and the calls recorded include a high-pitched squeal or a soft whistle. They call mainly during the breeding season and at the roost site.
Black-winged kites are monogamous and form pairs. During the breeding season, they become very aggressive and strongly attack intruders. Black-winged kites breed at different times of the year across their range. Although these birds nest throughout the year in India, they appear not to breed in April and May. Males establish territories and defend them from competition. Females move into the territories of males. Courtship is noisy and involves chases. The nest is a loose platform of twigs in which 3 or 4 eggs are laid. The female spends more effort in the construction of the nest than the male. Both parents incubate the eggs for about 25-28 days but when the chicks hatch, the male spends more time hunting. Females initially feed the young, sometimes hunting close to the nest but will also receive food from the male. After fledging the young birds continue to be dependent for food on the male parent for about 80 days. Young birds have reddish-brown feathers on the upperparts and on the breast. The reddish color is derived from porphyrins and is thought to provide the chicks some camouflage. Once breeding is complete females often move on to new territories sometimes deserting before the chicks fledge, leaving males to feed and raise the young. Both males and females show considerable nomadism. Unlike most birds of prey, Black-winged kites can raise multiple broods in a year.
23-11-2016 INLE LAKE, MYANMAR - ASIAN OPENBILL STORK (Anastomus oscitans)
The Asian openbill stork is predominantly greyish (non-breeding season) or white (breeding season) with glossy black wings and tail that have a green or purple sheen. The name is derived from the distinctive gap formed between the recurved lower and arched upper mandible of the beak in adult birds. Young birds do not have this gap. The cutting edges of the mandible have a fine brush like structure that is thought to give them better grip on the shells of snails.[8] The tail consists of twelve feathers and the preen gland has a tuft.[9] The mantle is black and the bill is horn-grey. At a distance, they can appear somewhat like a white stork or Oriental stork. The short legs are pinkish to grey, reddish prior to breeding. Non-breeding birds have a smoky grey wings and back instead of white. Young birds are brownish-grey and have a brownish mantle. Like other storks, the Asian openbill is a broad-winged soaring bird, which relies on moving between thermals of hot air for sustained flight. They are usually found in flocks but single birds are not uncommon. Like all storks, it flies with its neck overstretched. It is relatively small for a stork and stands at 68 cm height (81 cm long).
The usual foraging habitats are inland wetlands and are only rarely seen along river banks and tidal flats. On agricultural landscapes, birds forage in crop fields, irrigation canals, and in seasonal marshes] Birds may move widely in response to habitat conditions. Young birds also disperse widely after fledging. Individuals ringed at Bharatpur in India have been recovered 800 km east and a bird ringed in Thailand has been recovered 1500 km west in Bangladesh. Storks are regularly disoriented by lighthouses along the southeast coast of India on overcast nights between August and September. The species is very rare in the Sind and Punjab regions of Pakistan, but widespread and common in India, Sri Lanka, Nepal, Bangladesh, Myanmar, Thailand and Cambodia. It has recently expanded its range into southwestern China.
During the warmer part of the day, Asian openbills soar on thermals and have a habit of descending rapidly into their feeding areas. Groups may forage together in close proximity in shallow water or marshy ground on which they may walk with a slow and steady gait. The Asian openbill feeds mainly on large molluscs, especially Pila species, and they separate the shell from the body of the snail using the tip of the beak. The tip of the lower mandible of the beak is often twisted to the right. This tip is inserted into the opening of the snail and the body is extracted with the bill still under water. Jerdon noted that they were able to capture snails even when blindfolded. The exact action being difficult to see, led to considerable speculation on the method used. Sir Julian Huxley examined the evidence from specimens and literature and came to the conclusion that the bill gap was used like a nutcracker. He held the rough edges of the bill as being the result of wear and tear from such actions. Subsequent studies have dismissed this idea and the rough edge of the bill has been suggested as being an adaptation to help handle hard and slippery shells. They forage for prey by holding their bill tips slightly apart and make rapid vertical jabs in shallow water often with the head and neck partially submerged. The gap in the bill is not used for handling snail shells and forms only with age. Young birds that lack a gap are still able to forage on snails. It has been suggested that the gap allows the tips to strike at a greater angle to increases the force that the tips can apply on snail shells. Smaller snails are often swallowed whole or crushed. They also feed on water snakes, frogs and large insects. When foraging on agricultural landscapes with a variety of habitats, Asian openbills preferentially use natural marshes and lakes (especially in the monsoon and winter), and irrigation canals (especially in the summer) as foraging habitat.
The breeding season is after the rains, during July to September in northern India and Nepal, and November to March in southern India and Sri Lanka. They may skip breeding in drought years. The Asian openbill breeds colonially, building a rough platform of sticks often on half-submerged trees (often Barringtonia, Avicennia and Acacia species), typically laying two to four eggs. The nesting trees are either shared with those of egrets, cormorants and darters, or can be single-species colonies like in lowland Nepal. Nesting colonies are sometimes in highly disturbed areas such as inside villages and on trees located in crop fields. In lowland Nepal, 13 colonies found in an agricultural landscape had an average colony size of 52, ranging from 5 nests to 130 nests. The majority of these colonies were located on Bombax ceiba trees, with much fewer located on Ficus religiosa and Dalbergia sissoo tree species. Asian openbills preferred trees that were much taller and bigger than trees that were available on the landscape, and selectively used wild and native tree species entirely avoiding species that were important for resources such as fruits (e.g. Mangifera indica) despite such trees being much more common. Religious beliefs have secured important trees such as Ficus species, and agro-forestry has secured the most preferred species, Bombax ceiba, that Asian openbills prefer to locate colonies in lowland Nepal. The nests are close to each other leading to considerable aggressive interactions between birds on neighbouring nests. Both parents take turns in incubation, the eggs hatching after about 25 days. The chicks emerge with cream coloured down and are shaded by the loosely outspread and drooped wings of a parent.
Like other storks, they are silent except for clattering produced by the striking of the male's bill against that of the female during copulation. They also produce low honking notes accompanied by up and down movements of the bill when greeting a partner arriving at the nest. Males may sometimes form polygynous associations, typically with two females which may lay their eggs in the same nest.
Wednesday 23 November 2016
23-11-2016 INLE LAKE, MYANMAR - YELLOW RUMPED HONEYGUIDE (Indicator xanthonotus)
The yellow-rumped honeyguide (Indicator xanthonotus) is a sparrow-sized bird in the honeyguide family that is found in Asia, mainly in montane forests along the Himalayas. They are very finch-like but the feet are strong and zygodactyl, with two toes facing forward and two backward. They perch on honeycombs and feed on wax. Males tend to be territorial and stay near honeycombs while females and juveniles forage widely. They are brood parasites, laying their eggs in the nests of tree-hole breeders, possibly barbets.
The species has been recorded from northern Pakistan (Hazara and Murree Hills but the population here may have been extirpated western Uttar Pradesh and Himachal Pradesh extending into Nepal, Sikkim, Arunachal Pradesh and Bhutan (where it is relatively common). It is also found in southeastern Tibet and northern Myanmar. It is found in coniferous and dry-deciduous forest with rocky boulders and cliffs. May make altitudinal movements seasonally.
Monday 21 November 2016
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