This bird was one of a pair seen in the distance. When we walked along the water's edge, it began to make small alarm calls and, as we got closer, it began to approach us, calling more loudly, as though intending to threaten us. It came within a few metres. We quickly passed it, whereby it relaxed and returned to what we assume was a nest among driftwood higher up the bank. There were several people fishing nearby and it's a regular spot for walkers so this pair must be experiencing a lot of disturbance. Will avoid them next time.