Correct identification. Less cold hardy than some of the other Whistling/Tree Ducks [though none of them are completely frost resistant], so we don't see many of them in temperate region collections. Sweet little things though.
Dendrocygna javanica translates as 'Javan treeswan'. The terms tree duck & whistling duck are interchangeable. All eight species whistle, but not all of them sit in trees. The name Lesser Whistling Duck is on most current checklists, which is fair enough as they are the smallest of the group. However, I grew up calling them tree ducks, and the habit is hard to break. A charming genus whatever you call them.