Otidiphaps nobilis.
Tropical House, Walled Garden. The male/female pair were chasing each other up and down the full length of the pathway in the Tropical House. I can't remember if this one was the pursuer or the pursued. This behaviour carried on for 10 minutes or so, occasionally interspersed with one (male?) uttering an amazing-sounding call, very loud and lasting 5-10 seconds each time. I really wish I'd taken a recording. There was also some tail-flagging (not sure if that's the right term).
After a while, both individuals stopped and went back to their usual foraging.
