Australasian Bittern spotted in Porirua for first time in decades

An adult matuku or Australasian bittern is so good at being undercover, that it is often difficult to find and track. Photo / Imogen Warren

A "nationally critical" bird has been spotted in a Porirua park for the first time in decades, sparking excitement among bird enthusiasts.

The Australasian Bittern, or matuku-hurepo, was last sighted in the Porirua area in the 1980s, Whitireia Park co-ordinator Robin Smith said.

She was walking her dog at the Te Onepoto estuary a couple of weeks ago when she spotted the bird flying away in the dusk.

The light was starting to fade as Smith and another woman stopped on a bridge by the wetlands, and the other woman's dog splashed into the wetlands for a quick swim.

"It must have been in there and the dog disturbed it."

"The colouring on it is quite unmistakable.

"Bitterns have a conservation status of nationally critical, which means they're, you know, one step away from extinction."

She said the birds were known as "cryptic", meaning they were "very hard to spot".

It was hard to know exactly when one was last spotted in the area, and Smith did not know of any records in this park previously.

"But quite possible, you know, pre-European, they were there."

Greater Wellington Regional Council senior biodiversity adviser Kim Broad said bittern were "very secretive and rarely seen".

"They have inconspicuous plumage and when people come near they freeze in an upright position which camouflages them against wetland plants. The woman would most likely not have noticed the bird if it hadn't been disturbed," Broad said.

An adult matuku or Australasian bittern is so good at being undercover, that it is often difficult to find and track. Photo / Imogen Warren

"There are no records of the species in this area in current databases such as inaturalist and ebird. I don't know of any recollections in early descriptions of the area. It is likely that they were driven out of the area by farming and development in the middle of last century.

The number of bitterns continued to fall nationally "due to loss and degradation of small wetlands".

"They rely on networks of small wetlands to move between for food and breeding sites," Broad said.

"They might be drab looking but they are an interesting species due to their 'freezing' behaviour and 'booming' of the males birds during breeding season."

A Greater Wellington spokesperson posted about the bird on Facebook, saying it was "great news" the bittern had been spotted.

"The Whitireia Restoration Group undertakes pest control throughout the park with a focus on areas of wetland to provide a safe haven for residents and visiting birds such as this bittern," the spokesman said in a Facebook post.

"We would love to hear of any other sightings, so please let us know if you see a bittern at Te Onepoto or any other area of the Porirua Harbour on 0800 496 734.

"The sighting is a reminder that dogs should be kept under control in the area to protect native birds that forage in the estuary."