The Elusive Colombian Weasel - Observation of the Week, 12/9/18

Our Observation of the Week is this Colombian weasel, seen in Colombia by @sultana

Juan de Roux, an architect/designer and a professor in the Pontifical Xaverian University in Colombia, tells me that his primary natural history interest is snails (“There are over 100,000 species of mollusks, so I never get bored or get to know the whole thing; there is always something new to find and blow my mind.”) but like many other Observation of the Week posts, the observation which was chosen is not of the observer’s favorite taxon. However, that doesn’t mean he has no history with weasels.

When I was still a kid (13), my parents moved to a huge house in northern Cali, where I could spend most of my free time in the yard, exploring, as kids do...One summer day in the mid 90s I saw something amazing: the silhouette of what to me seemed like a tiny squirrel crossed the yard at a speed that was just off for a squirrel. During the next days I had a couple more encounters with the strange animal, one of them was very close. At the time I was able to determine this had to be some sort of ferret or weasel, however I could not take pictures or find anything about mustelids in my area (those were dark times without the internet) I hoped that someday I would be able to corner this animal again and picture it. But the years passed empty, but I held that memory. Now that I think about it, the animal I saw must have been the common Mustela frenata.

Flash forward to 2011 and Juan is at his parent’s country house in the mountains outside of Cali which was being remodeled at the time. The door to one of the bathrooms opens out into the backyard and, when he opened it, he found an animal trapped inside.

Recalling my childhood events regarding weasels, I rushed for my camera upstairs. I then stood under the threshold and took a good 14 pics, with my Nikon D80, as the little animal moved frantically all over the bathroom, looking for a way out that allowed him to avoid me. I recall a weird scent, I knew at the time that mustelids have odor glands, so I was not surprised, it was something like urine and insects. When I was done with the shots I left the door opened, I did not get any nearer, as it is best to exercise precaution with wild mammals.

Without giving it much more thought, Juan stored the photos on his computer and, for the most part, forgot about them; his computer has actually since died and its drive was wiped - “thank God my mom had saved the pics on her disc.” He rediscovered the photos a few weeks ago and, now an iNat user, said

[I] felt glad I could finally do something useful with them; I uploaded them into iNaturalist, as M. frenata at first, because - I confess - I know almost nothing about weasels. Something did not feel right with the ID, though. After a day, I decided to take a second look and found this very interesting paper...At first I was a bit skeptical, reading that this is a rare species. But could see in the holotype´s pelt a black oval spot in the ventral part that simply made this species unmistakable, so I corrected my id in iNat, and then the observation started getting starred.

To give you an idea of how rare Colombian weasels are, as of 2014, when that paper was published, there were no known photographs of a living one, so Juan’s nearly lost and forgotten photos are possibly among the first ever photo documents of a living individual of this species! “I still cannot believe I was lucky to see this animal and take these pics,” he says. “Needless to say, I never saw one of these again. But at least I can gladly assure that this area has remained basically unaltered for the past decade, so it has to be out there. Perhaps this animal is not so rare, but the lack of knowledge about it, combined with its secretive nature contribute to its rarity.”

Understandably, not much is known about the Colombian weasel, but it is believed to inhabit riparian areas and feed on fish and aquatic invertebrates and even has webbed feet! It is considered to be possibly the rarest South American carnivore, and is one of the smallest members of the order Carnivora, measuring 22 cm (8.7 in) in length, sans tail. And yes, weasels do produce a strong, musky odor from their anal scent glands when scared.

Juan (pictured above) was looking for local snail data when he first learned about iNatuarlist from a friend of his. “I looked it up in hopes of finding my beloved gastropods and found myself mesmerized,” he recalls. “Not by the mollusk observations in my country (modest at best), but by the concept that anyone with a camera (even with virtually no knowledge) could contribute to build precise distribution maps for all sorts of creatures.

For the last 2 decades I had been accumulating pictures of my own observations. I had an entire folder. “Perhaps someday I can make a field guide with all this stuff,” I used to think. This was really a side project, as the amount of field work required would have been impossible to do in a single lifetime, also because the trends in nature are dynamic, and the natural environment is changing very fast (alas unfortunately for the worse) so it is definitely not a one-man task.

Thanks to iNat I have access to a collaborative network of observers, which allows my observations to be part of something big, and have a real impact. The best part is that anyone can use this potent tool without needing to have a degree in biology, which allows everybody, no matter their background, to contribute to future research.

I always travel with my cellphone, provided with a camera and my iNat app. You never know what you might be lucky enough find.

- by Tony Iwane. Some quotes have been lightly altered for clarity. Thank you to @jwidness for alerting me to this observation!

- Juan sent me this aerial footage of the forests near where the weasel was found.

- Héctor E. Ramírez-Chaves, co-author of the Colombia weasel paper Juan found, has been in touch with Juan and will work on disseminating this find. 

-  iNaturalist has a network node in Colombia, Naturalista, which is operated by Instituto Humboldt

Posted on December 09, 2018 10:38 PM by tiwane tiwane


Congratulations Juan on a great observation! It's an inspiring account that will no doubt encourage many to keep their eyes open and cameras on hand. It gives one hope :)

Posted by patrick_campbell about 5 years ago

This is truly a once-in-a-lifetime observation and an amazing story. (Even in hindsight, the idea that these photos were almost lost forever stresses me out.) Thank you so much @sultana for sharing this with us, and @jwidness for drawing it to my attention. Juan, I hope you'll share more treasures from Colombia with us in the future and continue to be as enthralled with iNaturalist. There really isn't any site/platform quite like it.

Posted by bobby23 about 5 years ago

I love these stories!

Posted by twillrichardson about 5 years ago

Great work by all involved, including @jwidness, Héctor Ramírez-Chaves, and Bruce Patterson -- outstanding photos @sultana !

Posted by nateupham about 5 years ago

So awesome!

Posted by leptonia about 5 years ago

That's interesting. The color and pattern look very much like one I caught a very brief glimpse of in northern Ecuador in Imbabura province in the cloud forest near Pucará. It had that same rich chocolate colored coat, much darker than that of the M. frenata I've seen, and with a shorter single colored tail as well.

There was no opportunity to take a photo, hardly a chance to even see it. We were tracking radio collared spectacled bears and the little weasel bolted across the dirt road near where were.

Posted by earthknight about 5 years ago

Spectacular observation.

Posted by muir about 5 years ago

Wow. woW.

Posted by jmaughn about 5 years ago


Posted by lisa_bennett about 5 years ago

Way cool, and a nice story to go with the photos.

Posted by bluebell101 about 5 years ago

What i love the most is the rapidity with which this observation went from rediscovered photographs to contact with expert for potential publication. Well done, all!

"Luck is what happens when Preparation meets Opportunity"
-- generally misattributed to Seneca (

Posted by ellen5 about 5 years ago

I think there must be many more cases like this on iNaturalist, most of which don't get nearly as much attention. For example, here's an observation where the photo was taken in 2016, uploaded in 2018, and the species was first described in 2017:

Posted by jeremyhussell about 5 years ago

Fantastic. Many congratulations to the observer. Colombia is so cool... and so is iNaturalist!

Posted by birdizlife about 5 years ago

This is an example of how sites like iNat both expand our knowledge, and yet help preserve a species. In the past, the animal would have had to be captured (and perhaps dissected) to reveal it' s identity. Now we have photos (which of course have their limitations), and a base of people who can identify, question and perhaps confirm identifications. The weasel was allowed to live, to go back into it's habitat, to do whatever this weasel does, Yet humans have a good idea of what it was.

Posted by mamestraconfigurata about 5 years ago

To connect the dots on this thread as well as the observation itself, it led to this publication with @sultana and @heramirezc in 2019. After iNaturalist re-shared this on social media, it led to this story in Gizmodo, which led to a moment of fame as #toiletweasel. We're highlighting it again today on social media as a fun example of the impact of iNaturalist :-)

Posted by carrieseltzer over 3 years ago

#toiletweasel ! I love it. May as well have some fun while doing serious stuff!

Posted by mamestraconfigurata over 3 years ago

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