Mammals 105

Chapter 3

The Water Weasels - Minks and Otters

American Mink are a single species, Neovison vison, that are native to the US and Canada, but they have been spread by the fur trade to Europe and South America. Interestingly, the only other native species of mink was the Sea Mink, one of only two carnivores to go extinct in modern times when the last were hunted out off the East Coast in the mid-1800s. (Bless you Wikipedia!) Mink are avid swimmers, agile climbers and voracious hunters. If one gets into your pond, it will completely annihilate the population of fish, frogs, tadpoles, snakes, crayfish, insects, worms and just about anything else that moves, and you may never know what happened because they are as secretive as they are destructive. One of my buddies lost every fish in his pond every winter, without a trace, year after year, until he finally tracked prints through the snow down to a local stream and figured the mystery out. Mink are simply one of the most devastating pond pests in existence! These beautiful animals may be small, at only 15-18” long, under 3 pounds, and they are certainly a delight to watch, as are their larger cousins the Otters, but size notwithstanding, they will completely demolish your nice little backyard ecosystem.

By Roman Fuchs (Own work) [CC-BY-SA-3.0 orGFDL], via Wikimedia Commons

On the upside, Mink are solitary, territorial animals, very intolerant of other minks. They will savagely fight to the death to remove another mink from their territory, so chances are if you have a mink problem in your pond, it is likely only one solitary animal. Of course, females may be a bigger problem than males simply because they produce offspring, creating a larger population of devastatingly cute, destructive, little monsters to deal with, at least for the few months that the young will stay with their mother. 

Otter may be even worse than Mink, if only because they are much larger and very gregarious. River Otters weigh up to 30 pounds, 6 times what a Mink does, and are the most social of all the Weasels, hunting, playing and grooming in mixed groups of over a dozen, sometimes all members of the same family, but often with some unrelated members just hanging out for the companionship. Unlike the solitary Mink, River Otters may come visit in a group, and once your pond becomes Party Central, it won’t take long for them to clean out the refreshments. 

Sea Otters multiply the threat by another full order of magnitude. As if packs of 20 pound Hyper Minks weren’t bad enough, imagine having to deal with Giant Water Weasels the size of an average 12 year old! I was lecturing on Vancouver Island about using 18” deep initial shelves to deter wading predators like Herons and Raccoons when I realized that the audience was laughing at me. Quizzical, I asked what I had said that was so funny. A few exchanged eyebrows, then one spoke up: “Well, it’s not Raccoons we deal with. The River Otters were bad, but now there’s Sea Otters coming inland, killing all the Koi in a pond just for fun – they don’t even eat’em. As long as a man is tall and near 40 kilo, even a big dog runs. Raccoons!” I shut up. 

Turns out, after the fur trade reduced them nearly to extinction during what is still known at the Great Hunt, in 1911 Russian and American conservationists finally started to turn things around, and Sea Otters have been making a tentative comeback ever since. Native to the coasts of the North Pacific, Sea Otters hunt mainly shellfish, which they crack on a stone they keep in a pouch near their left armpit – really! – making them true tool users, like primates. However, they are certainly not adverse a free fish dinner inshore every now and then, so if you happen to live in the Pacific Northwest, their gain may be your loss, and there ain’t much you can (legally) do about it. 

Currently there is no known fail-safe design or installation technique that will completely protect the edible inhabitants of your backyard pond from the dreaded “Water Weasels”. Most states authorize trapping as a way to remove these pests, but you’ll have to check with local wildlife officials to verify the methods that are approved for your area.