A sea lion has given birth after unexpectedly swimming 60km inland along the Clutha River.
Department of Conservation rangers visited the mother and female pup last week after they were first discovered near Tuapeka in late January.
Coastal Otago biodiversity ranger Jim Fyfe said it was exciting and unexpected because they had not seen pakake do this before.
"While we know pregnant females push inland to escape the attention of males at this time of year, we never thought they might choose a breeding site this far from the sea," Fyfe said.
"This mother's behaviour raises a lot of questions for us. We know the females are very motivated to hide from males during breeding season, but just how far will they go? What trade-offs are they making in terms of access to their normal food?"
Fyfe told Midday Report that in the Auckland Islands sea lions were travelling 80km to get to their foraging grounds.
"So they are more than capable of travelling that far in a day on a foraging trip."
He said the mothers usually stuck to the same region but this mother seemed to have spotted "an opportunity" and had gone a bit further than others .
The mother is believed to be Jade, part of the Catlins population, who was born under a crib at Kākā Point in 2016.
Pakake are classed as nationally vulnerable and number about 12,000, with most settling down in the subantarctic islands.
Fyfe said there was a small number of breeding females on the south-east coast, but it did not meet the definition of breeding population, and satellite tracking in the winters of 2019 and 2022 did not record any sea lions entering the Clutha River.
"We expect the pup will remain in the area for the next few weeks, but we have no idea where the mother will take her after that. The mother will stash the pup while she forages so locals should be aware they may find the pup in unexpected places," he said.
"It will be interesting to see how the mother and pup use the river over the next few months, or if they return to the coast."
He urged people to give sea lions plenty of space and for boat-users to be aware they were in the area and slow to an idle when a sea lion was nearby.
That was echoed by Kaitiaki Rōpū ki Murihiku chair Gail Thompson, who said mana whenua asked everyone to be extra careful around the pakake and her pup.
The duo were found on Pam Hunter's property, who described them as one of life's little treasures.
"We're absolutely astonished, it's totally amazing. We've been going down to check on the pup, and it has been playing like a child would, including taking swims at the river's edge under the watchful eye of her mum," Hunter said, but she was curious where the mother was going to feed.