The young forest reindeer that wandered around Helsinki in January has been released back into the wild, as part of a species reintroduction program by the state forest management agency Metsähallitus' Wildlife Services.

The runaway startled residents of the capital's Haaga neighbourhood in early January before being caught by police a day later and taken to Korkeasaari Zoo.

It took several weeks to identify it as a rare Finnish forest reindeer, which is distinct from the semi-domesticated reindeer of Lapland. Veterinarians described the animal as tired and thin after a long, mysterious odyssey.

The Metsähallitus reintroduction programme, which began five years ago, has now been completed. One of the primary objectives of the project is to restore the forest reindeer to its former habitat in western Finland.

Over the course of the project, 81 animals in total have been released, either into the Seitseminen National Park in Pirkanmaa or the Lauhanvuori National Park in Southern Ostrobothnia. The parks now have a population of 40-50 forest reindeer each.

"Most of the forest reindeer made an easy transition to their new phase of life, but three years ago we had to seriously coax a cautious old reindeer and its calves, who had been caught in the wild, back out of the enclosure," said Metsähallitus' Milla Niemi.

Some forest reindeer have already been spotted along the gravel roads around Seitseminen.

"If you have enough patience to stay in the area for a longer period of time, it is quite possible to see a reindeer," Niemi said.

Satellite tags or GPS trackers have been fitted to some of the reindeer released into the wild. A majority of the animals have also been tagged with brightly-coloured ear tags, using colour combinations that allow for individual identification.

By doing so, the reindeers' future movements and survival will be able to be determined.

The Finnish forest reindeer, Rangifer tarandus tarandus, is a rare subspecies of reindeer native to Finland, different from the domesticated reindeer commonly found in Lapland.