ID help wanted with Mexican mammals

Hi all.

I wonder if anyone out there can help me identify some mammals (mostly squirrels) I saw on a a birding trip to western Mexico in 1999. The volume of “Mammals of the Neotropics” dealing with Mexico was supposedly about to be published back then, so I thought I’d wait till that came out to ID them. However, more than 10 years later, there’s still no published guide to mammals of Mexico away from the far south east, and nothing very helpful online, so I thought I’d see whether anyone can help with any of the IDs. I’d be really grateful for any help anyone can provide on the following:

A rather large, long-tailed squirrel, more or less all grey (lacking the red belly of Red-bellied Squirrel) seen in forest at Volcan de Fuego (Colima) and at La Bajada and Cerro San Juan (both near San Blas, Nayarit) – I suspect this (and/or the one below) is Collie’s Squirrel, but I can’t find any photos of this species online.

A small, plain-looking grey squirrel in mangroves at San Blas (Nayarit).

A small, greyish ground squirrel just outside Colima city.

A grey squirrel, looking very like Eastern Gray Squirrel, in forest along the Durango Highway (Sinaloa).

A large rabbit or small hare with rather short ears in forest at Volcan de Fuego (Colima).

A rather large, very dark brown, vole-like rodent (about the size of a Brown Rat) at Lerma Marshes, just west of Mexico City.

Finally, can anyone confirm that the bats roosting in the statue of the Virgin at Microondas La Cumbre (Colima) are Mexican Freetails?

If anyone can suggest IDs for any of these, or know who I might contact who could help, I’d be really grateful.


John Archer
London, England


  • Jon Hall

    I am really surprised by the apparent absence of information on Mexico… no field guides, trip reports, etc. I imagine there are lots of mammals there… but who is looking at them? Does anyone know?


    • John Fox

      I found a Wiki that is pertinent:

      It has a page on mammals and one on endemics. Some entries, such as Tehuantepec Jackrabbit, have enough info to know where to go look. The IUCN links on several species I checked had range maps.

      It’s not a field guide but is better than nothing. It’s a bit of a shame that there isn’t more organization and effort, there are a certainly some good mammals in Mexico and it is a natural extension of mammal watching in the US.

  • Morgan Churchill

    the vole like rodent sounds like some type of cotton rat, although I have no idea what species would be present in that area

    • John Archer

      Thanks Morgan. I’ve checked out some references, and I’m sure you’re right about it being a cotton rat. The range seems right for Hispid, Tawny-bellied and White-eared Cotton Rats, but it didn’t have yellow/ochre belly, which would rule out Tawny-bellied, and the habitat appears totally wrong for White-eared, so I guess it must have been Hispid.


  • squirrelprof

    I will take a crack at the squirrels…

    Ground squirrel in Colima was probably the Mexican ground squirrel (Spermophilus mexicanus…actually the new genus-species is Ictidomys mexicanus)but if it was a little larger with a prominent tail with rings on the tail and a reddish cast to some of the body (legs and haunches) then it could be Spermophilus annulatus…this is a pretty strinking ground squirrel and doesn’t seem to fit your description.

    Tree squirrels are a bit tougher as several species are highly variable in color…the two species that are very grayish in the Durango, Nayarit area are Sciurus colliaei and Sciurus aureogaster. Both are pretty variable in coloration and although aureogaster can have a red belly, it has a very gray form that looks much like an eastern gray squirrel as introduced to England and also has a completely black form. If you go to: then you can search for the pdf version of the account for Sciurus colliaei and in it are explained the often subtle differences between S. colliaei and S. aureogaster but you may never be totally satisfied.

    • John Archer

      Thanks very much for this info on the squirrels. The ground-squirrel was certainly not a striking animal, but a rather dowdy grey one, so I’m sure you’re right to suggest mexicanus.

      I’ve checked out the paper you suggested, and it seems that the squirrels around San Blas must be colliae on range, as aureogaster is apparently only in the mountains in that area of Nayarit. The ones in Colima and Sinaloa might be either species.

      John Archer

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