Thanks to Climate Change, Foxes Are Now Threatening a Rare Seal
Snow and ice are a seal’s greatest allies—until they disappear.
The Saimaa ringed seals of Finland, which live only in the landlocked lake for which the species is named, are some of the world’s rarest seals and depend on ice and snow piles for safe breeding dens. Thanks to climate change, those snow piles have started to melt earlier each year, leaving the mothers and their cubs vulnerable to a threat they’ve never really had to face: the red fox.
There are only about 300 Saimaa ringed seals left, and the critically endangered species already faces tough competition from commercial fishing interests—fishers have been known to kill the animals, which they consider competition for their catch.
Enter the red fox. The species is native to Finland and has never been known to attack Saimaa ringed seals. But this winter, for the very first time, a red fox was observed attacking and killing a seal pup.
The attack appears to have been possible because the snowdrift in which the pup had been raised melted early during a particularly mild and rainy winter, said Miina Auttila, a conservation biologist with the Finnish state agency Metsähallitus. The predation was captured on camera during Auttila’s Ph.D. work in which she tried to supplement melting snowdrifts by rebuilding them with shovels.
Other red foxes were seen trying to dig into seal lairs in 2014 and 2015. In addition to this winter’s kill, camera traps set up around Lake Saimaa recorded three other instances of pups and foxes coming face-to-face, although there was no evidence of additional attacks. (The pups were able to jump into the lake to avoid the other foxes.) The cameras also recorded evidence of raccoon dogs in the region, an invasive species not native to Finland.
Saimaa ringed seals have no natural predators—other ringed seals in the ocean have to contend with polar bears and Arctic foxes—so this is a potentially game-changing entry into the natural equation. The research team was surprised that the fox, which was half the pup’s size, could kill the animal.
Exactly why the red foxes have started approaching the seal dens remains unclear.
“For some reason, they spend more time at shorelines when snow conditions are weak,” said Auttila. “It is easier to travel along the shoreline ice than in the forest, especially during mild winters, when there is less snow.”
Will this predation continue? Global warming models predict that warmer winters will be the norm at Lake Saimaa. Auttila said that could increase the risk of foxes attacking the seals, especially if their dens continue to melt earlier than they used to or if there isn’t enough snow to build them in the first place. She said there is also a risk that the red foxes could quickly adapt their hunting techniques and start to target seals intensely if they have success killing pups.
Finland does not currently have a program for controlling predators as part of its effort to protect Saimaa ringed seals. Auttila said that might need to be an element of the conservation tool kit in the future if the risk of predation continues to increase.