Female sea lion Lorelie has been at Laura Keddell's property on and off for about three weeks.
She gave birth to a pup on the road outside Ms Keddell's house on New Year's Eve and has continued looking after her year-old offspring Kahu.
Ms Keddell said the family was ``blessed'' to have the animals in its garden.
``It's really amazing. I'm leaving them to it as much as I can.''
The year-old pup could be a handful, she said.
``Mostly they've been not threatening at all, but occasionally I get a bit freaked out.
``One day last week my 7-year-old and I were driving home and Kahu was circling the car and we couldn't get out. I texted my husband from inside the car and said `could you please distract Kahu'.''
The animal had the energy of a ``Labrador pup'', she said.
``Kahu is very playful and occasionally wants to engage with my kids. It's about 70kg, so every so often I feel a bit nervous about them playing in the back garden.''
The family's pets were wary around the new visitors, she said.
``We have two cats and 10 ducks. The cats have been giving them a very wide berth.
``One way we know the sea lions are on the move again is that the ducks are making a racket.''
Department of Conservation biodiversity manager Jim Fyfe said it was unusual for the mother to have not weaned off the year-old pup.
Lorelie would eventually move with her offspring to more remote Otago beaches, he said.
Six pups had already been born of the 15 to 17 expected on the mainland this season.
This would be a record.
``It's significant that breeding populations are again becoming established on the mainland. It's good to see.''
