Sea martin, Ploughboy, Inland tern, Riverbed tern, Tarapiroe
The black-fronted tern (Chlidonias albostriatus ), also known as sea martin, ploughboy, inland tern, riverbed tern or tarapiroe, is a small tern generally found in or near bodies of fresh water in New Zealand, where it forages for freshwater fish, arthropods and worms. It has a predominantly grey plumage. Restricted to breeding in the eastern regions of the South Island, it is declining and threatened by introduced mammals and birds. It is rated as endangered on the International Union for Conservation of Nature (IUCN)'s Red List of Threatened Species.
Measuring 29 cm (12 in) in length, the adult tern has predominantly grey plumage with a black cap typical of many terns. The underparts and rump are white, and there is a thin white streak running along the cheeks underneath the cap. The bill is red and legs orange. The black cap recedes from the bill in non-breeding plumage and becomes flecked with white.
Within New Zealand, the black-fronted tern is found from the southern tip of the North Island, and along much of the eastern South Island from Marlborough to Southland, and to Stewart Island. There is an outlying population along the Buller and upper Motueka Rivers in southern Nelson.
The breeding range is restricted to South Island only. It lives along riverbanks and can forage out to 10 km (6 mi) at sea in the nonbreeding season.
Fieldwork on the Wairau River in Marlbrorough showed that the swamp harrier (Circus approximans ) is a common raider of black-fronted tern nests for eggs, with the native kelp gull (Larus dominicanus ) and South Island oystercatchers (Haematopus finschi ) also raiding. Introduced mammals such as the cat (Felis catus ), stoat (Mustela erminea ), hedgehog (Erinaceus europaeus occidentalis ) and black rat (Rattus rattus ) have also been recorded.
Numbers of black-fronted terns are decreasing across its range, and the species is classified as endangered. Threats include several species introduced to New Zealand - stoats (Mustela spp.), feral cats, the brown rat (Rattus norvegicus ), hedgehog, dog, and from Australia, the common brushtail possum (Trichosurus vulpecula ), and Australian magpie (Gymnorhina tibicen ).
