There are calls for a small but very destructive pest to be added to the Government's Predator Free 2050 eradication list.
Forest and Bird claim the common house mouse poses a similar threat to our native species as the likes of possums and stoats, but they're not getting the same attention.
But the Department of Conservation (DoC) says the job of getting rid of pests is already hard without adding another to the list.
Mandy Brooke is in a constant battle to protect native plants and species at Bushy Park Tarapuruhi from predators. And there is one particular little rodent she has more trouble with than most.
"A lot of the work that we do is in response to mice, partly because they are so small, they breed so fast," she said.
Brooke isn't alone. Researchers in Aotearoa have found that the little house mouse poses a big risk to our biodiversity and native species.
"Mice have a whole ecosystem effect so they eat seeds, insects, lizards, eggs, birds, pretty much everything," said Forest and Bird Otago Southland regional conservation manager Chelsea McGaw.
But mice aren't being targeted by the government's Predator Free 2050 scheme which aims to eradicate possums, rats and mustelids - that's stoats, ferrets, and weasels. Forest and Bird thinks they should be.
"I just think they are really forgotten about in the 2050 strategy," said McGaw.
Overseas mice have been spotted preying on baby sea birds, a harsh reality that DoC can't rule out here. But it doesn't think the mouse needs to be added to the predator-free list.
"We believe that the species that we are currently targeting on that list are the species that do the most damage," DoC scientist Clayson Howell said.
But it's not just what mice eat that's worrying Forest and Bird, it's taking away what eats them. Mice are a key food source for all of the predators being targeted by the government. So taking them away without dealing with mice first could cause their numbers to explode.
"There is evidence and opinion from experts to show it would be best to target mice first," McGaw said.
"Everyone who is involved with Predator Free 2050 is under no illusions that this is going to be easy," Howell said.
"Adding extra species to the seven that are already prioritised is not gonna make it any easier."
Meaning sanctuaries like Bushy Park Tarapuruhi will have to continue their own battles with these tiny predators.
