City researchers found that Siberian flying squirrel habitats in areas of northwestern Helsinki had more than tripled in the past two years.
In the early spring of 2014, the city's environment centre uncovered a dozen flying squirrel habitats in the northwest of the city but two years later found 39 habitats in the same area.
The air-gliding rodents appear to thrive best in the city's large, forested Central Park, where 25 flying squirrel territories were found.
The Environment Centre's director Esa Nikunen says the evidence is clear.
"It's clear that after many decades of absence the flying squirrel has returned in droves to the capital," Nikunen said in a press release.
Squirrels in several areas
The squirrels have also taken up residence in other areas of the city, including the neighbourhoods of Kumpula, Veräjämäki, Pihlajamäki and Malmi.
Their habitats were revealed by researchers looking for the squirrels' droppings.
Nowadays, the centre says, the Siberian flying squirrels are no longer afraid of people, dogs or traffic. But unlike other city-dwelling squirrel species here, flying squirrels are not reliant on humans.
According to Nikunen, the growth of flying squirrel populations is the result of attention and management of the city forest's biodiversity. Siberian flying squirrels live in mixed forests, requiring pine trees for shelter and buds from leafy trees for food.
The Siberian flying squirrel is a protected species and it is illegal to disturb their nesting areas.
