Released from its cardboard overnight accommodation - dinner, bed and breakfast - the South Island robin is gone in a heartbeat, a dark flash through the forest understorey.
Orokonui Ecosanctuary's conservation manager, Elton Smith, is impressed.
"That's pretty quick for a fat tum," he says, poking about inside the box.
"I reckon this one's eaten 50 mealworms since yesterday."
Robins and numerous other birds, now threatened, would have inhabited the valley in the 19th century.
Since the erection of the 8.7km fence in 2007, Orokonui's managers have been arranging the reintroduction of an array of species.
Kaka, the forest parrot, and tieke/South Island saddleback were liberated last year, along with jewelled geckos from Otago Peninsula.
Robins were next on the translocation list, and they will be followed this spring by several breeding pairs of kiwi from the Haast area - the most endangered of the six varieties.
For the moment, though, the Silverpeaks robins are in the spotlight.
Their transfer, two years in the planning, has the blessing of the Department of Conservation and the Karitane runaka, Kati Huirapa ki Puketeraki, and if the birds establish at Orokonui they will become a hit with visitors.
When it comes to interacting with people, robins are New Zealand's most confiding birds - not so much tame as inquisitive, keen to investigate what insects and other invertebrate food human visitors have scuffed up in their territory.
But will the transferred robins stay in their new home?
They are free to fly back to their former home in City Forests Ltd's stands of mature Douglas fir, assuming they don't mind crossing four lanes of State Highway 1.
From above the canopy at Orokonui they will be able to see their old plantations.
What they won't know is that these trees are due to be logged in the next few years.
Otago University Associate Professor of Zoology Dr Ian Jamieson, who co-ordinated the transfer, says the Orokonui robins include a range of ages and some pairs.
They are all banded so researchers can keep track of them at Orokonui and record any returning to the Silverpeaks.
The Dunedin population, comprising just a couple of hundred birds, is one of only two on the east coast of the South Island - there is another isolated group near Kaikoura.
Over the past four years, Otago University zoology students have monitored and researched the Dunedin birds and for many years before that, teams of local ornithologists led by Peter Schweigman conducted annual surveys.
The nearest robins to these Silverpeaks and upper Silverstream birds are more than 100km away in the mountains of Northern Southland.
According to Prof Jamieson, the local robins are "holding on" but are far below natural densities.
Nest predation rates of 70% have been recorded, a devastating impact.
Rats, weasels, stoats, possums and feral cats are among the predators.
Even away from nests the adult birds are vulnerable, given their habit of perching on low branches and foraging on the forest floor for weta, caterpillars, spiders and earthworms.
They spend a lot of time scratching for food in leaf litter.
Mature exotic pine and fir plantations suit them because the forest floor is largely open, and it is hoped the large patches of kanuka, which typically have a sparse understorey, will feed and settle Orokonui's newcomers.
Prof Jamieson says that apart from the biodiversity benefits of a new population of robins, the Orokonui transfer will trigger novel research projects, focused on the birds' homing instinct, survivorship, breeding success in a protected environment, and genetics.
Long isolated, the Dunedin birds are known to be facing a genetic bottleneck.
Given a haven to breed in, robins can produce up to four clutches a year of two to four eggs per clutch.
They are strongly territorial and usually maintain pair bonds.
"In the future," says Prof Jamieson, "we could see Orokonui robins spreading into forested areas towards the city centre, although they're never going to reach huge numbers because of predators."
The immediate goal is to establish the robins inside the fence.
If all goes well, they will not only go forth and multiply but add charm and an up-close-and-personal element to Orokonui's expanding array of birdlife.
• Neville Peat, the author of Wild Dunedin, is a trustee of the Otago Natural History Trust, which manages the Orokonui Ecosanctuary.
