I revisited the area yesterday and found 5
Nankeen Night herons. They seemed 'agitated' in that they
flew up as soon as we tried to get closer than about 70m from
their perches. However 4 of the 5 stayed very close to the
willows from which they emerged and a couple re-entered quite
quickly.
I now consider they may well be nesting in
there, but I can't see any way of getting into this dense
vegetation - brambles are a feature - without disrupting the
birds. Hopefully by visiting every few days, if they are
nesting I should spot some immature birds when they fledge.
Martin