A distinguishing feature separating species is the number of digits on their hind feet. Seems about 1/3 of the species have 4, and 2/3 have 5.
In the Mono Basin, there's 2, maybe 3, species of k-rats, and all should have 5 rear toes - Dipodomys ordii, panamintinus and maybe microps (but probably not).
So, I thought I'd try some short-distance overnight sets with my 10 mega pixel Pentax homebrew, to see if I could resolve that infamous fifth appendage.
Here's the cam trap's photos...
Dunno about you, but I'm not seeing any 5th toes.
Which led me to check with CDFG biologist-bud Craig, at the Chimineas Ranch, who's had many a k-rat species in-hand. He reported that, yes indeed, the 5th toe is a tiny, interior dew-claw on all of the species, and it would be a surprise to be able to see it in a photo.
Comforting to know the cam traps are not to blame, but it does still leave us in the lurch on the specific epithet of the Dipodomys above.
So, let's see if we can sort it out. The 2 most likely species are ordii and panamintinus - Ord's and Panamint kangaroo rats. Dipodomys microps, the Chisel-toothed, is also a sagebrush scrub inhabiting k-rat of the east side, but I'm pretty sure its range ends south of the Mono Basin.
Collating size, pattern and color descriptions from multiple references, here's what I find:
|Feature||Dipodomys ordii||Dipodomys panamintinus|
|Back||yellowish buff w/ a few black hairs down center||ashy gray to dark brown|
|Sides||buff sides and white belly, diagonal line across hip||cinnamon sides and white belly, diagonal line across hip|
|Face||white spot above eye and behind ear, blackened whisker base||white eyebrow, white spot at base of each ear, pale cheeks|
|Feet||5 toes on extremely long hind feet||5 toes on normal size hind feet|
|Tail||long, tufted tail with dark dorsal and ventral stripes||tail over 60% of length and strongly crested with dark hairs dorsally, ventrally and at tip|
Not exactly apple-to-apples in their descriptions of the key characters, but not bad. Makes me lean towards ordii for our foraging friend, but just barely.
What about you? Anyone out there have either species in-hand before?
Whichever - they sure are adorable. I gotta say that whoever gave them the moniker "kangaroo rats" really did 'em a disservice. "Rat" evokes such a negative image, and these little joys are nothing of the sort. Should have been named "kangaroo gerbils" for their gentleness.
Here's a few Dipodomys heermanni I had in-hand on the Chimineas Ranch - the first with his cheek pouches full of seed from the live trap, and proudly showing us those 5 toes that Heermann's also has on his furry feet. As Craig said - the 5th is a wee piggy, for sure:
Adorable, absolutely adorable.
- E. W. Jameson, Jr., and Hans J. Peeters, UCPress - Mammals of California
- Tamara Eder - Mammals of California
- Smithsonian National Museum of Natural History - Panamint Kangaroo Rat
- Smithsonian National Museum of Natural History - Ord's Kangaroo Rat
- Smithsonian National Museum of Natural History - Heermann's Kangaroo Rat
- Wikipedia - Gerbil