You might be forgiven for thinking that a bird with the name Lesser whistling duck (Dendrocygna javanica) could sing a merry tune but apparently its song is only a two-note wheezy call. Instead, and rather remarkably, its outermost primary wing feather has a rather unusual shape and is said to produce a prominent whistling sound when the bird is flying. As I only saw this duck looking rather drowsy and sitting perfectly still, I can neither confirm nor deny its musicality.
Lesser whistling ducks can be found throughout the wetlands of Southeast Asia and lowland parts of the Indian subcontinent. I photographed this one in Cambodia, at the Angkor Centre for Conservation of Biodiversity about 60 kilometres outside Siem Reap. (You can read more about the conservation, rescue, rehabilitation and educational work of the ACCB here.)