Paignton's gibbons must be the envy of many other zoo gibbons (if only they had a way of knowing!). This is one of the brothers, Dylan or Deacon, singing very loudly. This is all they've ever known, living in the treetops on their island (except for the once in a blue moon escape). The Pileated are similarly blessed.
I recall that the orangutan area used to have gibbons on it as well - perhaps those ones would have had some way of knowing - though about jealousy I can't comment !
@Gigit One of the best Gibbon displays I know. As far back as I can remember they had Gibbons on the island in the lake, so its very much a Paignton speciality.