Doc, Southern Discoveries and the Fiordland Conservation Trust said in a joint statement yesterday the "plump, happy and thriving" kiwis were a living embodiment of the success of the Sinbad Gully native species sanctuary, two years on.
Doc Te Anau biodiversity ranger Hannah Edmonds said given the nocturnal birds were doing so well and numbers of pests caught in traps had decreased so significantly over the past two years, the department was happy to free them from their transmitters.
"We've been working with Southern Discoveries and monitoring them since their release and now it's time for us to let them do their own thing," Ms Edmonds said.
"We'll check on their welfare at every opportunity, but we don't like them transmitting for too long as it's best not to interfere."
Ms Edmonds said the fact that the kiwis were found together on the latest visit was a great sign for potential breeding.
"It's a bit too early for brood patches to be around, the patch of featherless skin that's visible on the underside of birds during the nesting season, but we did find them in the same roost site so it's safe to assume they're a breeding pair."
Other species present included rock wrens, keas, whios, wekas, large wetas and other large colourful invertebrates. The valley was also one of the last refuges of kakapos in Fiordland.
