Birds of a feather flock together, with thousands of spotted shags making Oamaru Harbour their home, roosting on a wharf and the breakwater.
The spectacular sight - at its best in the early morning or evening - is attracting locals and tourists, and the birds do not seem perturbed by having to pose for countless photographs.
When food is available at sea, the shags disappear in large flocks, abandoning their roosting spots.
Department of Conservation bio-assets ranger Graeme Loh said the North Otago coast between Cornish Head and Oamaru had a large proportion of the world's population of spotted shags because ledges on cliff faces offered ideal nesting spots.
It was not unusual to see hundreds or thousands of birds roosting at places along the coast, including Oamaru Harbour.
Other favourite roosting spots were at Katiki, Moeraki, the beach at the Waitaki River mouth, and the aptly named Shag Point.
‘‘They are a very colonial species. They see a few of their mates hanging out somewhere safe and come in to join them,'' Mr Loh said.
The shags preferred roosting spots where they would not be disturbed and ‘‘something with a bit of height'' for takeoff.
The wooden Sumpter's Wharf had been fenced off because it was dangerous and the harbour breakwater was difficult for people to access, making both good roosting spots.
The shags would disappear during the breeding season - from December to January - and return after fledging, Mr Loh said.
