The West Indian Whistling Duck is the largest of the eight species of Whistling Duck to be found in the world. It has numerous other common names, including Cuban Tree Duck, Black-billed Whistling Duck, Mangrove Duck, Night Duck, Yaguaza and Gingeon. Its Latin name, Dendrocygna arborea, means tree-swan, and acknowledges the fact that many of these birds spend large parts of their time perched in trees. With its long neck and legs, this duck is actually far more closely related to geese and swans, and like those birds, moults just once a year.
Generally, the West Indian Whistling Duck, whose call is a haunting four or five syllable whistle, is between 20 and 24 inches tall, and weighs about two and a half pounds. It has a chestnut brown forehead, with a dark brown/black stripe from the crown down the back of the neck. Its face is pale ginger, fading to grey and white on the chin, throat and neck. The feathers on the back and tail are medium brown, as are the wings. The primary feathers of the upper wing have silvery buff patches on them. The duck’s sides and flanks are black with distinctive white mottling. They have black beaks and the legs and feet are dark blue/black. In flight, the duck’s legs trail behind them and are longer than the tail.
Normally a night feeder, the West Indian Whistling Duck spends daylight hours roosting in mangroves, woodlands or swamps. At dusk they fly to their feeding grounds which are usually ponds (fresh, brackish or salt water) surrounded by thick vegetation or seasonally flooded grasslands. The ducks are largely vegetarian, feeding on fruits and seeds of grasses and other plants. They also eat freshwater snails, however, and some even develop a taste for tadpoles!
The breeding season varies from island to island. In Cayman it seems to occur at any time throughout the year, but most commonly at the onset of the rainy season in May/June. Breeding pairs often stay together for more than one season, and both male and female build the nest. The nests can be found in tree holes and on horizontal branches, although it is not uncommon for pairs to nest on or near the ground, or on ironshore outcrops in lagoons. Clutches typically number between 5-13 eggs and both birds take turns every 24 hours to incubate them. When the fledglings hatch, both parents assist in care for several weeks afterwards.
The first recorded sightings of the West Indian Whistling Duck in the Cayman Islands were made in 1916 by T.M. Savage-English. In his Notes on Some of the Birds of Grand Cayman, West Indies, Savage-English mentions them as being “by no means uncommon”. By 1971, they had been described in Avifauna of the Cayman Islands by D.W. Johnson et al as an “uncommon breeding resident”. In 1985, P.E. Bradley estimated a total, but falling population of about 320 ducks, comprised of flocks ranging from 12 and 60 birds. It is thought that between 1985 and 1991, the ducks suffered a further drastic decline, down to less than 100 birds in Grand Cayman, with similar losses in Little Cayman. From 1990 to 1992, the Cayman Islands Bird Club organised a series of watches in Lower Valley and North Sound Estates in Grand Cayman, but never found more than 28 birds in a flock. This was a low point in the fortunes of the West Indian Whistling Duck in Cayman.
The ensuing upward trend of recent years can be largely attributed to the work of just one man. In December, 1990, a single pair of ducks and seven young birds began to feed at the farm of Mr. Willie Ebanks, at Hutland, Northside, in Grand Cayman. Willlie grows fruit and vegetables and raises pigs, and he noticed that the ducks were nibbling at the pig food. So he began to put out extra feed for the birds. Soon the ducks were joined by others and by 1992, 16 pairs were regularly feeding at his farm. In 1995, the numbers were estimated to be close to 300 birds. The ducks arrive at dawn and return at dusk to dine on the split corn put out for them. In 1992, in recognition of his work, the National Trust for the Cayman Islands presented Willie with its prestigious Award of Distinction for Environmental Conservation. A reduction in illegal hunting on Little Cayman has also allowed the ducks to recover there, and in 1995, they bred on Cayman Brac for the first time in many years.
Also in 1995, the Trust hosted a study conducted by Fiona O’Brien, from Queen’s University, Belfast, Northern Ireland, to assess the duck population at Willie’s farm. The study aimed at establishing if and how the supplemental feeding programme had affected the bird’s behaviour; whether the ducks continued to use their remaining natural feeding and breeding grounds; and if the ducks were becoming overly domesticated. It is encouraging to report that the study found that many of the potential dangers have not yet materialised. The ducks are spending less than 30% of their time at the farm, so clearly still making use of their natural feeding grounds, and are teaching their young to do the same. Many appear to be breeding in the Central Mangrove Wetland, far from the farm. Today, the West Indian Whistling Duck is classed as a vulnerable species: its range is confined to the Cayman Islands, the Greater Antilles, and the Bahamas. The duck’s natural predators are few, but introduced species such as rats, feral dogs and cats, and, on some islands, the Indian Mongoose, present a very real hazard to its survival. The serious regional decline in its numbers in recent years is due principally to the rapid development of wetlands, the misuse of pesticides, and hunting. Hunting of the West Indian Whistling Duck is now illegal in the Cayman Islands, but poaching remains the biggest single threat to this bird. In 1995, the Cayman Islands Government expressed determination to protect this species with stricter control of hunting and gun licenses. With such measure in place, it is hoped that the numbers of ducks in Cayman will continue to rise to ensure its future in the wild.