The poo is thought to be from a rat.
The discovery of potential rat poo on an previously predator-free island has prompted conservationists to head out in force to rule out any rodent infestation.
A researcher found the droppings on Sealers Bay beach on Codfish Island/Whenua Hou, off Stewart Island, this week.
It has prompted a "full-scale incursion response" from the Department of Conservation.
Whenua Hou is 3km from Stewart Island and has been predator-free since 1998.
The island is home to the kākāpō recovery programme.
DOC Murihiku operations manager and response leader Tony Preston said the dropping has now been definitively identified as from a rat but there is enough evidence for the team to act now.
Workers equipped with tracking tunnels, camera monitoring gear and traps went to the island on Thursday.
"Whenua Hou is one of the most important sites for biodiversity recovery in New Zealand and any evidence of an incursion is treated very seriously. It only takes one pregnant rat to wreak havoc on a pristine ecosystem.
"Because of this we're taking a better-safe-than-sorry approach and doing everything we can to identify, isolate and exterminate any unwelcome arrival," Preston said.
Kākāpō operations manager Deidre Vercoe said a rat shouldn't pose any risk to adult kākāpō, but eggs and chicks would be vulnerable.
The critically endangered parrots were not expected to breed on Whenua Hou until early 2019.
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