The Minds and Manners of Wild Animals: A Book of Personal Observations

The habitants had chosen to locate their fortress between a large creosote bush and a tree-choya cactus (Opuntia fulgida) that grew on bare ground, twelve feet apart. When away from home and in danger, the pack rats evidently fled for safety to one or the other of those outposts. Between them the four entrance holes, then in use, went down into the earth; and there were also four abandoned holes. Connecting the two outposts,--the creosote bush and the choya,-- with the holes that were in daily use there were some much-used runways, as shown on the map; and each side of each runway was barricaded throughout its length with spiny joints of the choya. A few of the joints were old and dry, but the majority were fresh and in full vigor. We estimated that about three hundred cactus joints were in use guarding those runways; and no coyote or fox of my acquaintance, nor eke a dog of any sense, would rashly jump upon that spiny pavement to capture a rat. Beyond the cactus outpost the main run led straight to the sheltering base of a thick mesquite bush and a palo verde that grew tightly together. This gave an additional ten feet of safe ground, or about twenty-five feet in all. On our journey to the Pinacate Mountains, northwestern Mexico, we saw about twelve cactus-defended burrows of the pack rat, some of them carefully located in the midst of large stones that rendered digging by predatory animals almost impossible.