MOLES. Scapanus latimanus (Bachman)¹

Field characters.—Total length 6 to 6-3/4 inches (150-170 mm.), tail about 1-1/2 inches (38 mm.); body short and cylindrical; snout long and pointed (fig. 4); forefeet with greatly expanded and flattened palms and long heavy claws (fig. 5a); tail scantily and coarsely haired; no eyes or ears visible. Pelage short, soft, plush-like in texture; coloration uniform, dark brown, gray, or blackish (according to subspecies), appearing silvery when smoothed down. Habits: Strictly subterranean; live in tunnels formed by the animals themselves in the ground. Workings: Low raised ridges (containing runways) along the surface of ground; also, less commonly, mounds of earth with irregular surface, erupted from underground tunnels, and with no indication left of any opening to burrow (fig. 22).

Occurrence.—Present in small to moderate numbers locally across the Yosemite region; noted from Snelling eastward to Mono Mills and up to an altitude of 9500 feet (in LyeIl Cañon); especially common in meadows of Yosemite Valley.¹ Individuals live and work independently.

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¹Three slightly differing subspecies of moles occur in the Yosemite section. These, with their principal external characters, and ranges, are as follows:

YOSEMITE MOLE, Scapanus latimanus sericatus Jackson, distinguished by relatively large size and blackish coloration, is found in the Transition and Canadian zones, sparingly in the Hudsonian, from 3 miles east of Coulterville eastward to Tuolumne Meadows. It is abundant in Yosemite Valley.

SAN JOAQUIN MOLE, Scapanus latimanus campi Grinnell and Storer, a smaller, paler and more brownish colored form, occurs in the Lower Sonoran Zone, at Snelling.

MONO MOLE, Scapanus latimanus monoensis Grinnell, a still smaller and grayish-toned subspecies, was found near Williams Butte; its workings were noted at Mono Mills.

The workings of these three races are alike in all respects, save for differences conditioned by the various sorts of ground in which they occur. Thus the forage runways of monoensis in the dry sandy soil of the Mono Lake region are more likely to be caved in than are those of sericatus on the damp forest floor in the mountains.

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Fig. 4. Snout of Yosemite mole, from below, showing elongate tip beyond mouth, short front (incisor) teeth, and heavy covering of hairs on sides of face. Twice natural size.

The mole and the pocket gopher, and the respective workings of the two, are often confused in the popular mind. The two animals, and their workings, however, are entirely distinct in practically all respects save that both inhabit the ground. In most places in California, and this includes the Yosemite region, moles are much less common than gophers. This fact probably accounts for some of the misunderstanding which has arisen. By careful searching we found some evidence of moles at almost every locality which we visited in the section (below the 9500 foot contour) from the San Joaquin Valley eastward across the mountains to Mono Lake. On the floor of Yosemite Valley there is an unusually large mole population, and, as gophers are present also in considerable numbers, the habits of the two may there be studied and compared to good advantage.

The mole is rather more strictly subterranean than the gopher. The latter animal is not infrequently seen at the mouth of its burrow, and occasionally it comes clear out on the top of the ground. The mole, however, habitually stays below the surface. All of its foraging is done in the ground; even when excavating a burrow, the animal itself is not exposed to view from above. Moles are said to run about on the surface of the ground at mating time, but of this we have no direct knowledge.

In physical configuration the mole is admirably suited for life underground (pl. 27c). Its nose is long and pointed and equipped with numerous fine sensory bristles. The mouth opens on the under side of the head where dirt is less likely to enter when the animal is burrowing. The head joins directly onto the firm stout cylindrical body without any constriction at the neck region. The body as a whole is an 'entering wedge.' The forelegs are extremely short so that the feet lie close along side the head. The front feet are highly modified to form 'spades,' the palms being enlarged into thickened discs and turned outward, and the nails or claws being elongated and very stout. By means of these broad strong members the mole literally swims through the loose surface soil. The hind feet are much smaller and quite normal in shape and function. The body ends behind abruptly, and there is a short tail but scantily haired. The whole body of the mole is densely covered with short hairs of remarkably uniform length and texture which give a silky plush-like effect to the pelage. This sort of coat enables the animal to pass through the ground with a minimum of resistance; in other words, it acts as a lubricant.

The mole makes and uses two distinct sorts of underground passageways. One of these is the 'surface' runway, actually a subsurface run or subway, an inch or less below the top of the ground. The mole 'swims' along by strokes of the forefeet; its feet and body push the soil up in a low ridge, leaving numerous small lengthwise cracks showing on the outside (pl. 28a). These runs go here and there along the ground, between rocks and beside logs; they are made when the mole is searching for the worms and ground-dwelling insects which it uses as food. The second type of shelter, formed by actual excavation as in a gopher's burrow, is a regular underground tunnel, circular in section, and situated at a greater depth in the ground. The mole's tunnels are not so extensive and are of less diameter than those of any of the gophers of the region. To make these deep burrows the mole must force the loosened earth out onto the surface of the ground. This it does through laterals constructed at short intervals. Earth is loosened below ground (by the use of the forefeet ?), then is forced along the existing tunnel way presumably by the joint use of forefeet and chin (though the actual method of operation has yet to be seen), and it is then forced up a lateral. As we stated before, there is never any direct opening to the exterior. Each fresh lot of earth is forced into the vertical or nearly vertical lateral, pushing the earth already there out on top of the ground to topple over in one direction or another (see pl. 28b and fig. 22). Because of this method of digging, there are usually six inches or so of earth between the mole and the outside world. The freshest earth forms a central 'core' in the molehill. This core, of whose position there is seldom any external indication, can often be distinguished if the mound be sectioned in a vertical plane.

Fig. 5. Forefoot of (a) Yosemite Mole and of (b) Sierra Nevada Pocket Gopher. The Mole's palm is greatly expanded and the claws are relatively huge, which features together with powerful arm and shoulder muscles make it possible for the animal almost literally to swim through the earth; the Gopher's foot is less extreme, yet with elongated claws for special service in digging and with hairs between the toes which serve to increase the area of the foot when loose earth is being pushed out of or along the burrow. Natural size.

Practically all of our specimens of moles were taken in special mole traps designed to be set over a surface runway, and the use of such traps gave some information concerning the use of these runways. Sometimes a trap set over a newly made runway would catch a mole within a few hours, in other instances the trap remained several days before being disturbed. These facts indicate that there is considerable variation in the frequency with which the surface runways, once made, are traversed. On still other occasions no reoccupation of the run was noted. After one mole was caught in a runway, another individual sometimes appropriated the vacated system to its own use. On November 18, for example, a mole was taken in a run on the forest floor of Yosemite Valley. On the nineteenth the trap was sprung again, and being reset, caught a second mole on the twenty-first. It is believed that ordinarily but one individual inhabits a particular system of runways and tunnels at any one time.

Evidence of the activity of moles was found below the 5000-foot contour during every month of the year. In the summer and the fall months both surface runs and molehills indicative of deeper excavations were observed in Yosemite Valley; and at the end of December new runways were noted in places in the Valley where the ground was not frozen. During the height of winter in the high mountains when the ground is frozen to a considerable depth, conditions would certainly seem unfavorable for active existence of moles. But whether or not those animals become dormant, as do the chipmunks, we do not know.

Though there is no one kind of territory save solid rock where moles are absent, more of their work is to be found in dryish meadowlands than elsewhere. One runway was found in the gravelly ground beneath the boulder talus along the base of the north wall of Yosemite Valley. The dry needle- and leaf-strewn ground of the forest floor is often extensively marked by surface runways. The concentration of moles in these places is undoubtedly due to the greater abundance and accessibility there of suitable food.

The breeding season of moles generally, in California, is in the early spring. A male captured at Snelling January 9, 1915, was in breeding condition; a nearly grown young male was collected at the same place on May 29, 1915. Two individuals collected on June 2, 1915, 3 miles east of Coulterville and in Yosemite Valley, respectively, were, to judge by the unworn condition of their teeth, animals born during the current season. Another juvenal mole was obtained 3 miles east of Coulterville on June 6. These data suggest that the breeding season at the levels indicated is early, probably just at the end of the winter months.

As already intimated the mole's diet consists almost exclusively of animal matter. In lowland districts, earthworms probably constitute a large portion of its fare. For example, the stomach of a mole trapped by one of our party at Snelling, January 9, 1915, contained "long sections of earthworms" together with some "dirt." As earthworms are relatively scarce or absent in the higher mountains the moles there must feed on other sorts of 'worms.' Elsewhere it is known that they eat the larvae of certain insects, such as cutworms (moth larvae), and it is probable that, in the higher mountains, too, such larvae form part of the mole's bill of fare.

A "Macabee" gopher trap set in a surface runway of a mole on the sandy 'second bottom' at El Portal on November 27, 1914, caught a mole during the night. When the trap was examined on the following morning the trapped mole had been completely defleshed, the skull was almost clean save for ligaments, and the skin was turned inside out leaving an almost perfect skeleton. This probably was the work of another mole, though there is the possibility that a shrew, following the mole's run was responsible.

The mole, it will be seen from the above account, occupies a very different niche from that of the gopher. Yet the two inhabit the ground; and in their regular existence both promote in various ways the development of soil and, consequently, conditions that are favorable to plant growth. This principle has been set forth in detail in the chapter on the gopher. (See p. 141.)