‘Like a giant bird box’: the volunteers building huge snowdrifts for Finland’s pregnant seals | Marine life
Eight hours shovelling snow in -20C might not sound like the ideal day out, but a committed team of volunteers in Finland are working dawn to dusk building enormous snow drifts for one of the world’s most endangered seals.
The Saimaa ringed seal was once widespread across Finland but is now confined to Lake Saimaa in the south-east of the country, where just 495 of them remain.
The seals make “snow caves” inside snow drifts where they raise their young and protect them from the elements and predators such as red foxes – but as the climate warms, the snow is disappearing.
Clockwise from top: volunteers check the suitability of the ice to build a snow cave under the supervision of Heikki Härkönen, coordinator at the Finnish Association for Nature Conservation; Riikka Alakoski, from the Finnish forestry agency inspects an artificial den; and records the location of a breathing hole (the image has been altered to obscure its location); a small den in the ice
To save these rare seals, 300 volunteers spend days shovelling snow into piles 7m long and 1.5m high around the edge of the frozen lake. Last winter they made 200, and the seal population is growing as a result. “It’s kind of a snow cave,” says Vincent Biard, a PhD student and volunteer from the University of Eastern Finland. “The seals come from under and dig into the snow drifts to create a cave where they can give birth and raise their young.”
Volunteers meet at first light and work until dusk. They get around on foot or skis, dragging their equipment with them over a distance of 10km. Biard describes the day as “kind of fun”, and adds, “you actually have an impact, which is nice. If we don’t do it, then they would just go extinct quite quickly.”
More than 300 pups have been born in artificial snowdrifts since they started making them in 2014. “We are on a rising growth curve, so things still look pretty nice,” says Jari Ilmonen, coordinator of Our Saimaa Seal Life, which is an EU-funded programme. “We are doing what we can, so we have to have hope and positive thoughts.”
Saimaa seals are less than 1.5 metres long and each one has a unique fur pattern – individual to each animal, like human fingerprints. In the late 1980s their population dwindled to its lowest point, with fewer than 200 left, driven by hunting and deaths caused by fish traps. Accidental deaths in fishing nets remain a challenge.
Now, the seals are fully protected but the threat of the climate emergency looms large. Between 1925 and 2002, the maximum thickness of the ice decreased by 1.5cm a decade. In mild winters the ice caves can collapse, leaving the pups exposed, with up to 30% of them dying.
Human-made snow drifts are larger and “more durable than natural snow drifts”, says Ilmonen. “By the first half of February most of the natural ones had melted away, but the manmade ones prevailed.”
In the future, ice cover is expected to disappear before the pupping season has ended. There have already been some winters where there has not been enough snow to create an artificial drift. In some cases the seals have been known to breed elsewhere, but with no snow “just a few would hang on”, says Ilmonen.
However, scientists from the University of Eastern Finland are working on plan B.
They are creating artificial dens, or nest boxes, that mimic the real thing, with preliminary research showing the seals use them for resting, giving birth and nursing their young. The nest boxes could be used in ice-free winters, researchers say. Biard says: “The long-term perspective is we don’t know if snow drifts are going to be sufficient. So the team is developing artificial nest boxes, similar to what you put in the garden for the birds.”
There are about 40 dens on the lake, where three pups have already been born, but Ilmonen wants to get more out there. “If you think that there are maybe 500 seals and maybe 100 pups born each year, you’d need a lot of the boxes,” he says.
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