Subspecies Subplot

C. c. acadicus Bailey	c. frondator Mearns Sonora beaver	C. c. pallidus
C. c. baileyi Nelson	C. c. idoneus	C. c. phaeus Heller Admiralty beaver
C. c. belugae Taylor\Cook Inlet beaver	C. c. labradorensis	C. c. rostralis
C. c. caecator Bangs Newfoundland beaver	C. c. leucodonta Gray Pacific beaver	C. c. repentinus Goldman Sonora beaver
C. c. canadensis Kuhl Canadian beaver	C. c. mexicanus Bailey Rio Grande beaver	C. c. sagittatus
C. c. concisor	C. c. michiganensis Bailey Woods beaver	C. c. shastensis Taylor Shasta beaver
C. c. carolinensis Rhoads Carolina beaver	C. c. missouriensis Bailey Missouri River beaver	C. c. subauratus California Golden beaver
C. c. duchesnei	C. c. pacificus Rhoads Washington beaver	C. c. taylori Davis

So theoretically there are 25 subspecies of beaver in the united states. The three in yellow are native to California. These subspecies are supposed to have slightly different skull morphology and slightly different ‘habits’. When subspecies don’t look noticeably different, or act noticeably different, they are defined as a variety of the species that is separated by some geological feature but generally could, if it weren’t for circumstances, breed comfortably with others outside its subspecies. Different races of humans are not called ‘subspecies’ for obvious reasons, but different types of dog are. There is some early description of golden beaver only knowing how to make ‘bank lodges’ instead of island lodges. In his famous chapter that is often cited, Grinnell noted that these beavers have lost their skill at making canals,  somewhat at damming, and even that they are less likely to leave footprints!

Grinnell speculated that the golden beaver wasn’t ideally suited to the higher elevations, and even though they were eventually reintroduced and did fine (thank you very much) there are some who have argued that is because of their cross breeding with other beavers from heartier strains.  Importantly, Grinnell did much of his research at a time when there weren’t many beaver left in california to get an adequate sample. Remember that way back in Morgan’s writing there was discussion of “slave beavers” based on the observation that some skins had dented heads, and were obviously the ones that did the damming work by breaking boards with their skulls.

Nowhere does he mention that regional and terrain differences might have more to do with varied behavior than genetics. For example, beavers on wide bodies of water like the colorado river build bank lodges and do not build dams, regardless of subspecies. When Rick saw our ‘bank lodge’ with built up wood atop he was confused. Was this a ‘bank lodge’ or an ‘Island lodge’? His work on the Shasta subspecies in the lassen area occurred very soon after the last volcanic eruption, and probably isn’t a good read of what is ‘typical’ either.

So one discussed goal of the “Historic Range of Beaver in California work group” (still working on the acronym) is proposing a “Lets Investigate Early Subspecies’ (LIES) paper as well. An interesting conversation is taking place with several genetic experts to see what testing would involve. A very important caution is that most historic beaver skins were preserved using arsenic, so care must be taken when collecting samples. Interestingly, we just had word that beavers were also ‘reintroduced’ in other states, some of the very states that supposedly were used to ‘reintroduce’ heartier california beavers. What this means is that whose beavers are whose might be anyones guess!