The New Zealand bittern (Ixobrychus novaezelandiae ) is an extinct and enigmatic species of heron in the family Ardeidae. It was endemic to New Zealand and was last recorded alive in the 1890s.
Common names for this species include New Zealand little bittern, spotted heron, and kaoriki (Māori). The scientific species name also has numerous junior synonyms.
Although a small bittern, the species was larger (length about 14.75 inches (38 cm)) than the little bittern (25–36 cm). Few specimens are known, and of these doubt exists even about the sex of some, making published descriptions unreliable. Differences from the little bittern include a larger buff patch on the upper wing, black upper parts streaked light brown, under parts streaked dark brown and rufous-buff.
In recent times, the bird is only known with certainty to have inhabited the South Island of New Zealand, with most records from Westland. Although subfossil remains have been found in the North Island, reports of living birds may have been of misidentified Australasian bitterns. The first scientific specimen was reportedly obtained at Tauranga in the North Island by a Reverend Mr Stack in 1836, but is now untraceable. The holotype specimen in the Museum of New Zealand was taken from the head of Lake Wakatipu in Otago. The recorded habitat for the species includes the wooded margins of saline lagoons and creeks.
Walter Buller quotes a Mr Docherty, who was familiar with the bird in Westland:
The bittern is recorded as eating mudfish and worms in captivity, when given in water.