The Karoro penguin colony could be annihilated amid growing fears the new Greymouth-Ross cycle trail is giving dogs unfettered access to burrows.
The Grey District Council today warned that anyone walking their dog off the lead on the cycle trail could be hit with a $300 infringement notice.
A penguin was mauled to death by a dog overnight, and two others were killed in the past fortnight.
The Department of Conservation today found two adult birds unharmed in a burrow by the Karoro Domain, but a third was dead and bloodied on the cycleway.
Autopsies confirmed the other two recent attacks were by dogs, and DOC biodiversity programme manager Brad Edwards said a roaming dog appeared to have been responsible for the death last night.