Adorable Killer Ermines Found To Contain Three Distinct Species Of Fluffy Weasels


Rachael Funnell

Social Editor and Staff Writer

clockApr 15 2021, 11:35 UTC
Adorable Killer Ermines Found To Contain Three Distinct Species Of Fluffy Weasels

Don't be fooled by the fluff, these babies are masterful hunters. Image credit: Jonathan Koivuniemi/

Defining species is an inexact science, and as the tools available to us grow all the more sophisticated, we can sometimes find new-to-science species hiding within populations of animals we’ve been studying for some time. This exact scenario recently expanded our library of a predatory mammal known as the ermine, which was found to consist of three distinct species. The research, published in the journal Diversity and Distributions, has named them Mustela erminea (Eurasian ermines), Mustela richardsonii (most North American species), and Mustela haidarum, which is found only on Haida Gwaii Archipelago of British Columbia and Prince of Wales Island in Southeast Alaska.

These silken, fluffy killers might not look all that dangerous, but ermines are remarkably efficient hunters despite their slight frame. Their diet ranges from small mammals like voles and mice to larger game such as rabbits and chickens, and they are found across the globe.


For the lead author on the new research, Jocelyn Colella, the mustelids are a familiar family. Her own previous research investigated how populations at high altitudes could become isolated during periods of freezing and then meet again as the landscape warmed. As curator of mammals at the University of Kansas Biodiversity Institute, she’s had the chance to study ermines extensively in the field – but this latest discovery was facilitated by some in-depth analyses of frozen specimens from across the globe.

Using tissue samples, Colella and her team were able to compare North American ermines to animals from Europe and Asia. They sequenced their genes and compared skull morphologies, trying to identify if there were genes or anatomical features that were consistently different enough within certain populations to merit a new species.

Sure enough, their results found distinct enough features to constitute three distinct species, with one (M. haidarum) being limited to Prince of Wales, Southeast Alaska, and Haida Gwaii off the coast of British Columbia. Their speciation (an evolutionary process that sees different populations of the same animal adapt enough to become a distinct species) likely occurred as their range had a different climate to the surrounding landscape with comparatively fleeting bouts of ice.

Ermines don a brown coat in the summer. In winter, they are totally white except for the black tip of their tail. Image credit: Djin Polsky/

“These groups were interbreeding, and then this population got stuck on these islands and then a lot of time passed, more ice, and they just slowly became their own species,” Colella said in an interview with KTOO, and she believes there could be many more species out there to be discovered. “We just have no idea what’s out there and we really need to be using these new techniques to better understand the diversity of these islands.”

[H/T: Gizmodo]