“Two species of Whistling-ducks can be found at the Singapore Botanical Gardens. There are subtle differences between the two species but they are very similar in appearance. Their similarity is telling as many have problems identifying and differentiating one species from the other. I have been stumped in the past but have learned how to recognise and tell them apart. To differentiate them, you will have to look closely at the eyes and flanks. The Lesser Whistling-duck (Dendrocygna javanica) (above left) has distinctive yellow eye-rings (below left), whereas the Wandering (D. arcuata) (above right) has none (below right). The Wandering Whistling-duck has distinctive black and white plumes on their flanks, whereas the Lesser has hardly any flank plumes to show.
“Since both species of Whistling-ducks are often seen together, the question of crossbreeding has often cropped up and been speculated. We can now confirm that they do crossbreed. Two visits were made to view a new family that included both species of Whistling-ducks as parents recently (below). The family consists of six ducklings, a Lesser and a Wandering Whistling-ducks that are apparently their parents. Observations showed both Lesser and Wandering parents actively looking after their clutch of ducklings. Their protective instinct is obvious for all to see as they chased away any perceived intruders, including both species of Whistling-ducks, that get too near their offsprings.
“The hybrid ducklings are covered with downs that are greyish and white (below left). There are spotted patterns on their bodies and stripes on their heads. Zooming in for a close-up view of the duckling’s bill, a small patch of orange-coloured marking can be clearly seen at the tip of its upper mandible (below right). This is possibly the ‘egg tooth’, which has been described in one of the earlier postings of BESG LINK. During my second visit which is about two weeks after the first, the ‘egg tooth’ had disappeared from the more developed ducklings. Noted that their downs have also turned a little brownish.
“It will be interesting how the plumage of the hybrid juveniles will appear as they develop into full-grown adults. Will they look more like daddy or more like mummy? Will they have yellow eye-rings or black and white flank plumes? If we can keep track of these juveniles, some of these intriguing questions may have answers in the near future. Right now, I don’t even have any idea which species is dad and which is mum.”
Kwong Wai Chong
9th July 2012