Saimaa ringed seal
Saimaa ringed seals give birth towards the end of February. They dig a nest in snow on top of lake ice. Snow nest gives shelter for young seal pups. If there is not enough snow, young seals do not survive. In 2010s, volunteers help seals by building artificial piles of snow on lake ice. Studies by the University of Eastern Finland showed the ringed seals would nest in man-made snowdrifts the same as natural snowdrifts.