The Javan Tree Duck: Emerging from Obscurity

Abstract

Early each morning, having completed inspection of the parrots and softbills, I enter the gated waterfowl enclosure, throw several handfulls of game-bird pellets and Flamingo meal in the water and await the arrival of the flotilla. Eventually, the lake surface before me is covered with a gaudy assemblage of busily feeding Mandarins, Wood Ducks, Chiloe Wigeons, Chestnut Teal, Orinoco Geese and others, but, usually, among the first to arrive are a couple of very small ducks, riding low in the water, grebe-like, their subdued brownish colors augmented with black primaries and beautiful, rich chestnut upper tail coverts. This pair quietly go about their serious business of breakfast, running their bills over the surface and, more often than the rest, disappearing beneath for extended periods, bobbing up again like corks. Unlike their relatives, the Australian Plumed Tree Ducks, they hardly ever call while feeding.

At other times, this pair of Javan Tree Ducks is most often seen in the company of the Plumed Tree Ducks and the largest of the eight members of the Tree Duck genus Dendrocygna, the Cuban Tree Duck, a striking contrast to the Javans, which, at about 500 grams, less than half the mass of a Cuban, are the smallest members of the genus.

Javan Tree Ducks, also known as Indian Whistling Ducks, Lesser Tree Ducks, and Lesser Whistling Teal, are one of the commonest ducks of the Indian sub-continent and Sri Lanka, and are also found throughout southeast Asia, from southern China, Taiwan, Okinawa, Burma and IndoChina, south through the Malay Peninsula to Borneo, Sumatra, and Java, as well as the Nicobar and Andaman Islands, in the Bay of Bengal (j o hn s g a rd , 1978). This species is one of the few Anatids restricted to tropical Asia, somewhat puzzling considering the general richness of that region's birdlife.

Despite its abundance and broad range, including many countries where birds are or were massively exported for aviculture, the Javan Tree Duck has traditionally been a great rarity in bird collections. As recently as the 1970s, Frank Todd (1979) who, while Corporate Curator of Birds at Sea World Corporation, assembled an enormous collection of waterfowl at its several parks, considered it "quite scarce in ... collections," "very rare in North America" and "seldom bred'.' The latter fact is particularly galling in view of the great fecundity of the very closely related Fulvous Tree Duck (Dendrocygna bicolor), exceedingly common in captivity, and prolific, sometimes to the point of embarrassment, when unexpected ducklings attain full flight and threaten to establish feral populations.

It appears the situation may be changing. Reviewing a compilation I made of duck breedings catalogued in the first five volumes of the International Zoo Yearbook (Zoological Society of London, 1961-5), covering 1959 to 1964, I found no listings for Javan Tree Ducks at all. Volume 12, for the year 1970, lists only the private collection of Dr. Robert Bucci, in Ravenna, Italy, where he did manage to breed 24 that year. I am grateful to Karen Hickey, a San Diego Zoo librarian, for providing me with the Javan Tree Duck statistics from Volume 28, the most recent, covering 1986. The situation had, by then, changed significantly. Eight collections bred the species: two in England, the Jurong Bird Park in Singapore, and five American zoos; San Diego, Los Angeles, Philadelphia, the New York Zoological Park and the Miami MetroZoo. The last institution had spectacular success, producing 48 ducklings. The situation continues to improve. Javans are now propagated by commercial breeders, and while still expensive compared to many ducks, a pair can be purchased for considerably less than a hand-reared African Grey Parrot.

The Emerald Forest pair came from Sea World Florida, in Orlando, in August of 1990. Released into our large, well-fed lake with 15 other species of waterfowl, they have presented no problems whatever, coming through winter nights of temperatures in the 30s without difficulty. Among the smallest of our ducks, they hold their own against large and notoriously aggressive species. They thrive on commercial pellets and Flamingo meal, supplemented with what they may glean from our natural lake. We look forward to the breeding season.

In light of its diminutive size, this bird should lend itself well to small enclosures and as, unlike some other members of its genus, full-winged individuals do enjoy perching in trees (Iohnsgard, 1978), it is to be recommended for...