Protection for an endangered duck was one of the core elements in a Russian billionaire's bid to buy a coastal farm and build a $40 million home.
Alexander Abramov, one of the world's wealthiest people, was given Government permission to buy 214ha of land at Helena Bay, a hidden gem in a remote area north of Whangarei.
The mineral magnate, estimated by Forbes to be worth $7.5 billion last year, paid $15.9 million for the property and is now building a palatial mansion on the land.
Experts say the mammoth property will rival the $35 million Chrisco mansion in Coatesville, now rented by Kim Dotcom.
The project has employed 80 people during construction but Mr Abramov had to agree to Overseas Investment Office conditions before the sale in 2009 was approved.
Documents released under the Official Information Act show one of the promises the deal hinged on was creating a 2ha wetland as a sanctuary for the pateke, also known as the brown teal duck.
The papers from Land Information New Zealand say one of the conditions was: "The development of the entrance wetland area into a series of ponds with riparian planting to further enhance the habitat for the national endangered brown teal duck. The area will be fenced and separated from the farming operation."
Mr Abramov also promised to protect the 2ha area by registering a QE II National Trust open space covenant with tracks and public parking.
"The applicant proposes to grant and to facilitate public access to the entrance wetland area once completed, which will allow the observation of many native species, including the endangered pateke."
A letter Department of Conservation director-general Al Morrison to the OIO said the pateke was a "significant component" of the indigenous fauna in the region and noted that Mr Abramov had also promised to control predators and pests to protect the teal.
"The department believes that the suggested management proposals, provided they are fulfilled by the applicant and are on-going, will benefit New Zealand by protecting and enhancing sites containing indigenous vegetation and the habitat of the nationally endangered brown teal ... the benefits will be substantial," Mr Morrison wrote.
Only 600 pateke existed in 2004, but conservation efforts have increased the population to around 2000 nationwide.
Chris Seel, managing director of Northland Coastal Developments and the director of Helena Bay Holdings, is working for Mr Abramov to create the residence.
In March, he told the Herald that the foreign investment was hugely beneficial to the region and New Zealand.
"Eighty-two families are being fed for three years through New Zealand's biggest recession and there will be lots of people working there once it's finished," he said.
"The project has 82 fulltime employees and 12 to 20 specialist contractors brought in from outside the local area because skills were not available in that region."
Mr Seel said a $250,000 environmental commitment was made at the time of purchase but about $1 million had been spent.
Work carried out includes:
* Hill areas fenced to stop cattle trampling saplings and reaching the coastline.
* Thousands of possums culled.
* A hydro seeding unit established.
* Invasive tobacco weed and woolly nightshade infestations reduced.
* Archaeological sites mapped with a plan to restore a significant Maori pa site.
Many in New Zealand strongly oppose foreign investment in property, particularly in coastal land and farmland.
The Campaign Against Foreign Control of Aotearoa opposes deals such as Mr Abramov's, saying it is not in the country's interests to sell businesses or land.
Mr Abramov appeared on last year's Forbes rich list as the 21st-richest man in Russia and the world's 124th-richest man. He is 52 and married with three children.
The magazine said he got a start as head of a research laboratory before the Soviet Union imploded and then made a fortune by exporting metals and coal from the Urals and Siberia.
"After the 1998 Russian financial crisis, he bought up hobbled steel companies and coal mines on the cheap," Forbes said.
His Helena Bay Holdings got permission to build a 233m walkway with a 14m long, 3.6m wide floating pontoon along the untouched coastline of Otara Bay, at the northern end of Helena Bay about 1km off the main road, to give him better access to his fishing boat.
The billionaire, who plans to make twice-yearly visits, is allowed to dredge up to 200sq m of seabed on the northern side of the bay until 2015.
The application to the Overseas Investment Office said Mr Abramov could have wealthy overseas guests staying at his lodge residence.
* Alexander Abramov, 53
* Made his money in steel and mining
* Has a fortune estimated last year at $7.5 billion.
* Lives in Moscow
* Married with 3 children
* Russia's 21st and world's 124th richest man
Source: Forbes 2012 Rich List.