The Fiordland crested penguin or tawaki is
The West Coast Penguin Trust is worried birds could die during a bumper beech forest cycle this year.
The Department of Conservation is putting a plan in place to deal with what was expected to be a mega mast year, in which heavy beech seeding produces an abundance of food for rats, mice and stoats.
Even though the penguins' breeding season does not start until July, the trust is beginning preparations for the mega mast.
The group's manager, Inger Perkins, said they were concerned the event could hamper the breeding success of Fiordland crested and blue penguins.
She said there was a similar event in 2016 and the consequences were disastrous.
She told RNZ: "In one site where we had 10 cameras I think in every single nest the eggs or the chicks were taken by stouts, so something was clearly different and we believe it was because of a beech mast nearby."
The West Coast Penguin Trust set out to reverse the decline of blue penguins in 2006, but it quickly recognised the need to extend its conservation work to both penguins in the region, as well as other threatened seabirds.
The Fiordland crested penguin, or tawaki, is just one level removed from the highest level of threat status in New Zealand at "nationally endangered". Blue Penguins are a few levels further down, being "at risk - declining".