Caspian Tern

Maori Name: Taranui

Sterna caspi

Maori name Taranui                                                                                

The Caspian Tern is the world’s largest tern, which has a scattered distribution. It breeds in temperate parts of all continents but South America. It may be quite a recent colonist to NZ because none were recorded by naturalists until 1860, but is now considered a native. There are about 3000 birds in different locations around the country. Although numbers rose to a peak in the 1970’s, they have declined again possibly due to disturbances by human activity.

The Caspian tern is grey with short, black legs, and a long, thick, red-orange bill with a black tip. The head is white with a black cap although in winter this gets flecked with white. In flight the tail is less forked than other terns, and from underneath the wings are black-tipped. Their call is a harsh ‘caaaa’ and when in flight this will often be heard before you see them. Juveniles utter a persistent high-pitched mewing.

In NZ they breed on the 2 main islands usually on the coast but some inland. Single pairs and small colonies consisting of up to 100 pairs breed on sandy beaches and in many harbours and estuaries. The nests are scraped out of the sand and are often sited in windswept places. Breeding is in spring and summer when 1-3 light speckled stone are laid. The adults incubate the eggs for 20-22 days and the chicks will hatch over several days with one adult guarding them for the first 5-10 days. They are fed on fresh fish from the parent birds, offered whole. The chicks fledge around 5 weeks but will be fed for several months. These terns will disperse from their breeding sites in autumn, usually keeping within 100 kilometres but South Island birds tend to move to the warmer north. The chicks go with their parents but will stay in the wintering spots until they return to the colony to breed at 3-5 years.

Although they roost in flocks they mainly feed alone. They eat many types of surface swimming fish up to 20 centimetres in length. Usually they will fly about 5 to 10 metres above the surface of the water with their bills downward, and when they spot a suitable fish will plummet down submerging themselves. Caspian terns also fly inland to feed on freshwater lakes as well.