Yep I think it is a juvenile Nankeen Night Heron, used to have a couple of roosting colonies of them around here. Lots of storms over the past decade or so has knocked one of the roost's trees around so much that they are rarely sighted there now. I'll attach a photo below to show mature adults look. Nankeen is an 'old' word to describe their brown colour. Normally during the day these birds stay under heavy leaf cover. I got this photo when a trail bike rode past opposite were I was and spooked the birds over toward me.
