A small colony of little shags were spotted nesting in the trees above the Waikouaiti River yesterday.
Researcher Dr Chris Lalas said the birds were native to New Zealand, and were a subspecies of an Australian variety of shag.
They were different from their Australian cousins in that their plumage could be varied, from being all black to having black backs and white fronts.
They tended to nest in trees overhanging bodies of water, he said.
He believed the largest Otago colony of little shags was on Quarantine Island.