Three ways of being a ground squirrel

Three species of squirrel that Jessa and I have photographed and shared here before. So as an excuse to share more/again, I will highlight their different approaches to being ground squirrels. 

Rock squirrels, Otospermophilus variegatus, are affectionately called "plague squirrels" by some Southwesterners; they are in fact a reservoir species for Yersinia pestis. As I wrote in a previous post, "In some ways, rock squirrels appear to be intermediate between tree squirrels and the other ground squirrels. Their tails, for example, are far bushier than those of most other ground squirrels, and while it's not something they do frequently, they can climb trees quite well." They are, of course, past masters at climbing rocks; most of my original rock squirrel photos are from the Grand Canyon. (All photos in this post, however, are Jessa's.) They will use natural cavities but also dig their own burrows, which serve as escape cover, routine shelter at night and during extremes of either heat or cold, and denning sites. Their burrows may also include food caches.

Yuma antelope squirrel, a.k.a. Harris' antelope squirrel. (The latter name, and the scientific name Ammospermophilus harrisii, commemorate the naturalist Edward Harris, a contemporary and companion of John James Audubon. The Harris' hawk and Harris' sparrow are also his namesakes.) They climb rocks exceedingly well but I have never seen one in a tree or bush. Of the four or five species of antelope squirrels, this is apparently the only one to excavate its own burrows, though the rest will use burrows of other animals.

Black-tailed prairie dogs, Cynomys ludovicianus, have taken ground-squirrelhood to such extremes that some people don't seem to realise that they are squirrels at all. Large, rotund, and short-tailed, they don't seem to fit the generic "squirrel" template. (Then, too, there's the name.) Burrowing is one of the defining chacteristics of this species and of prairie dogs generally—there are five species, with the black-tailed being the most widely distributed—and so far as I'm aware they don't climb anything at all but their own tunnels. Like tree squirrels and beavers, however, they have an outsize effect on their own habitat, helping to shape and define an entire ecological community.