Blackpool must be the only other UK zoo which has(now) bred Pileated Gibbon in recent years- apart from Twycross. ISIS currently lists them as having 3.1. Is this another error- surely they don't know the sex of the baby yet...?
I believe though Twycross have bred them fairly regularly they have had a shortage of female births? They are currently listed with 5.3. There was one young there when I went recently.
They had the pair that did not breed together then received the 2 new males one of which was paired with Ivy . When I visited Blackpool last year I asked a keeper how the pairing was going and was told signs looked good . Just as with the Gorillas a change of male had the desired effect . Next they need to sort out the Orangs .