Why are there three different ways to label North American Beaver?

There are only two existing species of beaver: the North American beaver and the Eurasian beaver. When making an observation why are there three different options for this keystone species. What can be done to only have 2; The North American beaver, Castor canadensis and the Eurasian beaver, Castor fiber.

welcome to the forum

I only see two beavers in Castor, what is the third?


I’m not seeing three beavers either. I went to the website and checked the suggested IDs on one of my C. canadensis observations; only the North American beaver was suggested (as well as an otter and a mink).

I wrote in the genus “Castor” and the top suggestions were the genus itself, C. fiber and C. canadensis, and then the suborder and family they belong to. (And then muskrats!) The word “Beaver” yields a similar list, though interestingly C. fiber was absent. Are you using a language other than English to find IDs? I could imagine different lexical groupings that result in some other, less related species appearing.

There is also another species with the common name of ‘mountain beaver’, though it isn’t closely related to nor that similar to other beavers. Looks like it is actually most related to squirrels, but gnaws at the base of trees so some people associated it with beavers.



Oh that’s a cute little critter! Looks superficially a bit like a rodent version of a wombat.

That’s a good shout, I wonder if that’s appearing as a suggestion in some places as well. I could certainly see that being confusing at first.

Muskrat can pop up as a possibility among the choices under “beaver”, presumably because of its nickname Musk-beaver. That potentially could cause confusion as beavers and muskrats are roughly similar and could be mistaken for each other (they often are when seen in the wild).


Maybe the concern is with the existence of subspecies within C. canadensis? So a beaver in the US or Canada could be identified as:

  1. Castor canadensis - American Beaver
  2. Castor canadensis canadensis - [no separate common name]
  3. Castor canadensis carolinensis - Carolina Beaver

That makes three possible “ways.” (There are also three other American beaver subspecies on iNat). However, because the subspecies are included within the main species C. canadensis, searching for the American beaver on iNat will show you all American beavers regardless of whether they have a subspecies ID.


I’m thinking the issue that @ebbp is seeing may be that three different “Beaver” taxa show up if you type “beaver” as a suggested ID.

None of these is the species for either the American Beaver or Eurasian Beaver. That’s really just due to the interaction between the common name “Beaver” being used for the genus, family, etc. and how iNat prioritizes among multiple entries that contain the same letters.

If that’s the actual problem at issue here, you can fix it by typing "beaver " (with a space) or even “am be”. Either of those will bring up the American Beaver at the top of the list.


Thank you, that is how I have been looking and imputing my observations. Is there a way to suggest removing the second and third option so only American Beaver pops up?

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So Gerald is a musk-beaver???

You can type “american beaver” or “am beav” and it will prompt only the american beaver. The other suggestions for “beaver” would be useful to other observers.

That is where my confusion lies. How is it useful to other observers if there are multiple options for a species where there is only one they might have observed.

American Beaver has been introduced in Eurasia so in some parts of the world the local Castor might not be obvious.

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The first three options are all correct, they are just not as specific as entering “American Beaver”. You can choose any of them and you will not be wrong, because iNaturalist functions on the basis of a nested taxonomic structure. If you choose a higher level, you’ll find that others will quickly help refine your identification to species level.

You’ll find the same thing for other organisms. For example, type “osprey” and you can choose from the family, genus, species or subspecies level. It’s not possible to remove these entries entirely because a species legitimately belongs to a genus and that genus to a family, and so on, and identifiers often want to identify at a higher level than species.

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Beavers are an unusual case in that there are only two species, so showing a comprehensive list of all options would theoretically be simple. But for many groups, it’s actually quite useful for the search to return broader results such as the tribe, family, etc. Sometimes species don’t have common names at all, and only the broader groups do; sometimes the broader groups are the closest a user might feel confident identifying; sometimes it’s just not possible to ID to species with some groups, or doing so requires photographing specific features that aren’t always captured, so it’s helpful in avoiding overly specific IDs when genus/tribe/etc appear in the suggestions; sometimes the computer vision itself isn’t really sure what it’s seeing beyond a broad group; etc. And as other have mentioned, it’s not wrong for someone to identify a beaver as Castoridae.

For example, it’s useful for the search to yield the order Coleoptera when searching “beetle” because for a lot of people, a ranked list of the most common beetle species in their area without any higher grouping is going to give them a ton of beetles they don’t feel confident identifying, or which might not match what’s in the image. For many folks, outside a few familiar species, all they might know is that they’re looking at a beetle, so it’s very helpful for them to have a way to select Coleoptera directly.

That said, I understand that it seems a bit silly sometimes, and I do wish there were some way to flag taxa that are monotypic or not-many-typic for special treatment by search results. I occasionally see horsetails ID’ed as the order Equisetales, which is correct but unnecessarily broad, since the only genus in the order is Equisetum. I assume this happens when people don’t know there’s only one genus in the order, and select the order from the list because they don’t feel very confident in their knowledge; and it’s not wrong, so it’s not really a problem. But it feels like it would be useful if curators were able to flag those somehow so that if a taxa only contains one subtaxa, the more specific taxa appears and the broader one doesn’t (assuming the user is typing in a common name, and not a precise scientific name).

But absent that architecture in the data, I do see the value in displaying taxa of varying degrees of precision in the search results.