MARIPOSA BRUSH RABBIT Sylvilagus bachmani mariposae Grinnell and Storer

Field characters.—General appearance much like that of small domestic rabbit; ears shorter than head (fig. 35a), half as broad as long; tail short, white of tail much restricted. Head and body 10 to 12-1/2 inches (255-315 mm.), tail 1 to 1-1/4 inches (25-32 mm.), hind foot 2-2/3 to 3 inches (68-75 mm.), ear (from crown of head) 2-1/2 to 3-1/8 inches (65-80 mm.); weight 17-1/2 to 22 ounces (500-631 grams). Coloration dark brown with heavy overwash of black; general effect of coloration deep gray rather than brown; under side of body grayish white; under side of tail white. Workings: Paths or run ways 2-1/2 to 3 inches wide, on ground beneath chaparral. Droppings: Flattened spheres about 1/4 inch in diameter, scattered on ground at feeding places and along runways.

Occurrence.—Common resident in foothill region (Upper Sonoran Zone) on west slope of Sierra Nevada. Recorded from Lagrange and Pleasant Valley eastward to El Portal (to altitude of 4000 feet on south facing mountain side immediately north of El Portal). Lives on ground beneath chaparral, seldom venturing into the open. Seen actively abroad at dusk of evening and morning.

Fig. 35. Heads of (a) Mariposa Brush Rabbit and (b) Sacramento Cottontail Rabbit; one-half natural size. See pp. 227, 228.

Smallest in point of size among the rabbits of the Yosemite section is the Mariposa Brush Rabbit of the western foothill country. Hunters refer to this as the "blue rabbit" because of its distinctly bluish gray cast of coloration in contrast with the brownish tones of the cottontail. The average visitor will be likely to see more of the cottontail and jack rabbit than of the brush rabbit, as the former species forage generally in rather open situations, while the latter habitually keeps close beneath the chaparral, even when foraging, and, moreover, is to be seen as a rule only in the early morning and in late evening.

In general form and appearance the brush rabbit resembles the cottontail, to which it is not distantly related. The two species are 'rabbits' in the restricted sense of the word, in that their young are hairless at birth and are born in sheltered nests of some sort, and in that the adults browse close to cover and when frightened seek safety beneath shrubbery or in holes rather than in flight as do the hares (jack rabbits).

The brush rabbit is about half the weight of a cottontail and measures, on the average, smaller in all dimensions than that species. The ear of the brush rabbit is shorter than the head; its greatest length, as measured from the crown of the head, is only about twice its width. (See fig. 35.) The head of the brush rabbit is blunter and broader as compared with that of the cottontail, and the tail is smaller and shows less white. There is a conspicuously darker, colder, grayish tone of coloration in the brush rabbit, which is to be contrasted with the yellowish brown coat color of the cottontail.

In general the deportment of the Mariposa Brush Rabbit is like that of its nearer relative. It habitually carries its ears up in a nearly vertical position. Not infrequently the red tinge of the ears, resulting from the sunlight shining through them, is the first thing to catch the observer's eye. Usually, when suddenly come upon, a brush rabbit will 'freeze' and remain perfectly still; under such circumstances it might easily be mistaken for a rock. When it decides to move it does so abruptly and a few jumps place it under the shadow of the chaparral. There the observer's eye can scarcely follow it, so closely does the color of the animal's pelage match the general tone of the environment; with a few further scurrying movements the rabbit is entirely lost to view. This animal is an adept at dodging about in and among bushes. As long as cover is available, its safety is fairly assured.

The Mariposa Brush Rabbit does most of its foraging in the dusk of evening and in the early morning hours. Sundown, whatever hour that may be in the different seasons of the year, is the best time to watch for brush rabbits. Then they come out to the margins of the brush thickets to browse, or go hopping about here and there in the spaces under the canopy of chaparral. At El Portal, in early December, they suddenly became active at about 5 P.M.; near Coulterville, in May, they were not out in the evening until about 7 o'clock. The time of appearance of the brush rabbit is roughly parallel to that of the various species of bats. Probably the early hours of the night are spent in foraging. The early hours of the morning soon after daybreak are also spent in some activity. In May and June the animals were seen not infrequently between 5:30 and 6.30 A.M. But soon after they disappeared for the day.

Individual brush rabbits are localized in their range. Once having found the haunts of a particular animal, the observer can be almost certain of finding it there subsequently at the proper hour. Thus near Coulterville one was sighted one evening in May. Next morning it was within 5 feet of where it had been seen before, and later that morning it was again seen close to the same spot.

The Mariposa Brush Rabbits, at least during the fall months, get much of their forage from the brush plants. The greasewood, which serves them as shelter, is not ordinarily used for food; but two other foothill shrubs, the blue brush (Ceanothus cuneatus) and wild broom (Hosackia glabra), which has a clump of long, flexible, hay-like stems, are resorted to freely. The rabbits nip off the stems of these two plants and eat them, discarding the leaves. Much rabbit sign, indicating repeated visits by the animals, was seen wherever these plants formed the chief vegetation. In the spring months grass and other fresh herbage grows about the borders of the chaparral and the rabbits turn then to this food source. With the food habits just indicated, and with its timid and retiring disposition, the brush rabbit is never likely to become the pest to agriculture that the cottontail is. On the other hand, it is a desirable game animal.

Brush rabbits bring forth their young chiefly during the early months of the year. Two juvenal animals, taken near Coulterville on May 11 and 12, 1919, weighed only about one-third as much as adults and were in the dusky-hued first pelage. To judge from the growth of domestic rabbits these animals were probably not over six weeks old when found by us, and so had been born in the later part of March. These youngsters, however, were already out and foraging independently at the margin of the chaparral, just as adults are wont to do. A female, giving evidence of suckling young, was taken 3 miles east of Coulterville on June 1, 1915.

Several of the local carnivorous birds and mammals are known to prey upon rabbits and this is probably one reason why the Mariposa Brush Rabbit keeps so closely to the cover of the chaparral. The presence of these natural enemies, and the limited forage available to the brush rabbit, are two factors which serve to keep down the numbers of the species.