Wilma and Ian McDonald, of Balclutha, each won the society's highest conservation honour, the ''Old Blue Award'', which is named after the Chatham Islands black robin named Old Blue - a bird that conservationists say saved the near-extinct species in the 1980s.
South Otago branch chairman Ray Johnstone said Mr and Mrs McDonald had made a major contribution to Forest and Bird fundraising by rearing native plants.
''They produce 400-600 native plants a year from their native plant nursery,'' Mr Johnstone said.
The plants were sold at the branch's native plant sale fundraiser in Balclutha every August.
''They've raised a heck of a lot of money for the branch over 25 years,'' Mr Johnstone said.
The money raised had supported local projects such as the weeding of Otanomomo scientific reserve and the trapping of pests in the Catlins, where endangered yellow-eyed penguins lived.
Mr Johnstone and local trapper Jim Young also won the society's ''Pestbuster'' award at the conference.
The rat-shaped statuette recognised their success in reducing pest numbers across 220ha of Catlins coastline.
''We reckon we've caught over 200 stoats, 150 possums, 180 rats, 24 cats and 12 ferrets since 2008,'' Mr Johnstone said.
Apple bait was used for possums, while eggs and peanut butter was used to attract stoats to the traps, he said.
''We've got the predator numbers to a low enough level that they're not causing trouble for breeding yellow-eyed penguins.''
Mr Johnstone said the group's next project was to reduce the number of rats at Long Point, where muttonbirds were nesting.
By Robert Steven.
