Australasian Bittern

Maori Name: Matuku

Botaucarus poiciloptilus

Closely related to herons and once common in wetlands throughout NZ, the Australasian Bitterns are heard more than they are seen. When startled they may stand tall, neck fully stretched with head and bill pointing skyward or drop slowly into a crouched position with their head fully retracted. The dappled brown plumage then makes them almost invisible among the reeds and scrub.  The Bittern has a booming call that has been likened to that of a distant foghorn that is loud from a distance but deceptively muted from close by.

Nests are built by the female who breaks down all the reeds within reach until a platform is made 25-30 cm above the water.  Laying is in September to November, with a staggered clutch of between three and five eggs, that hatch 25 days later.  The mother will feed the chicks until fully fledged at seven weeks.

Both sexes have a general brown plumage made up with both buff shadings and dark brown shadings.  The throat is a whitish colour and the upper mandible is brown while the lower mandible is greenish.  The eyes are yellow and the legs are a greenish colour.

These birds are to be found in tall, dense beds of raupo and reeds in freshwater wetlands, wet habitats with a mixture of water purslane and willow weed, and damp pasture with large clumps of rush or introduced tall fescue.  They are fairly widespread, with breeding spots in S. Australia, Tasmania, New Caledonia and the Loyalty Islands.  In NZ they are widely distributed but mostly found in Northland, Waikato, Bay of Plenty, Manawatu, southern Wairarapa and on the West Coast.

A protected rare native, Bitterns have declined through drainage and reclamation of wetlands, and cattle grazing in swamps which damages breeding cover. However, approximately 56,000 ha of c. 76,000 ha (75%) of the West Coasts remaining wetlands are protected within public conservation land. Habitat restoration and management of weeds is carried out within these areas which will consequently improve habitat for the Bitterns. Communities along the West Coast are also working together with DOC to improve wetland habitat on private land.