Bird Watch – Caspian Tern

Caspian tern. Photo courtesy Steve Attwood

Caspian tern. Photo courtesy Steve Attwood

The Caspian tern (Sterna caspia) – Taranui in Māori – is easily disturbed by people, dogs and off-road vehicles, so Christchurch photographer Steve Attwood, who took this photograph, spent a long time, patiently slithering across the muddy lake bed, pausing often to prevent the birds from panicking.

Steve took his photographs at a colony of about 100 pairs, way out in the (mostly) dry lake bed of Te Waihora/Lake Ellesmere. The colony was situated on what normally might be a small, very low island but after of very dry spring, it was then surrounded by hectares of bare, flat, dried mud lake bed. Like most keen bird photographers, Steve always takes the greatest care to ensure his photographic subjects are not in any way disturbed.

The sleek Caspian is the largest of the native terns in New Zealand (it has a 1-metre wingspan) and is distinctive for its black head markings, its white body, silver-grey wings and its bright orange-red bill. Although their numbers are still relatively small, they are a familiar bird in estuaries, inlets and some inland lakes and rivers throughout both the North and South Islands.

They breed mainly around the coast and their colonies are usually close to other terns or gulls. An average nest has one to three light-flecked eggs in a shallow, scraped out in the sand and they breed from September through to January. Chicks usually fledge in 33-38 days.

Favourite food includes small, surface-swimming fish like yellow-eyed mullet, piper, smelt and tuna (eel).