BLACK-TAILED JACK RABBITS. Lepus californicus
rabbit form but racy in build; ears longer than head (fig. 33); legs and
feet relatively long and slender. Head and body 18 to 19 inches (460-480
mm.), tail 2-1/3 to 3-1/2 inches (60-90 mm.), hind foot 4-1/2 to 5-1/2
inches (118-140 mm.), ear from crown 5-3/4 to 6-1/2 inches (147-165
mm.); weight about 5 pounds (2.3-2.4 kilograms). General coloration
above pale yellowish brown, ticked with black; under surface of body
varying from pale buff to white; tail black above. Workings:
'Forms' (resting places) on ground beneath bushes; also paths leading in
direct course across open country. Droppings: Flattened spheres,
yellowish brown in color, about 3/8 inch in diameter, scattered on
resident in Lower and Upper Sonoran zones on west slope of Sierra Nevada
where recorded from Snelling and Lagrange eastward to Bower Cave and to
slopes of Bullion Mountain (subspecies californicus). Also
present in small numbers east of mountains in neighborhood of Mono Lake,
as at Mono Lake Post Office (subspecies deserticola). See
footnote for details. Inhabit chiefly open plains country, though some
individuals live about clear areas in the chaparral or in open woods.
16Two races of the
Black-tailed Jack Rabbit are found at the opposite ends of the Yosemite
cross-section. A form of intermediate characters in the southern San
Joaquin Valley connects these two, and so they are treated as subspecies
of one species.
CALIFORNIA JACK RABBIT, Lepus
californicus californicus Gray, inhabits the coastal region of
central California, the Sacramento Valley, and the northern part of the
San Joaquin Valley, and is common in the western part of our Yosemite
section from the plains below Snelling and Lagrange eastward into the
foothill country to near Bower Cave and to the slopes of Bullion
DESERT JACK RABBIT, Lepus
californicus deserticola Mearns, ranges over the interior deserts of
California and the Great Basin and was found present in small numbers
near Mono Lake Post Office, east of the Sierra Nevada. It differs from
the preceding in its paler, more ashy coloration and in its slightly
smaller average size.
The California Jack Rabbit is a common species on the
plains and rolling lands at the eastern margin of the San Joaquin Valley
where our Yosemite section begins, and it also occurs to a limited
extent in open areas in the foothills among digger pines and chaparral.
In a few places jack rabbits enter the lower margin of the yellow pine
belt, but they go no farther upward. The main forest belt of the central
Sierras, the Transition and Canadian zones of the west slope, is devoid
of rabbits of any sort. On the east side of the mountains there is a
closely allied form, the Desert Jack Rabbit, which occurs in small
numbers about Mono Lake.
Our jack rabbit is strictly speaking a hare, more
closely related to the White-tailed Jack Rabbit than to the cottontail
and brush rabbits. The present species lives entirely out on the surface
of the ground without taking to underground shelters. Its young at birth
are fully haired and almost ready for independent existence. The adults
when alarmed instead of hiding in shrubbery or bolting down into holes
make off in the open and trust to their legs for safety. These are all
characters of hares as contrasted with true rabbits.
The present species is a black-tailed jack rabbit.
The upper side of the tail, which is the surface presented to view when
a hare is running, is extensively black and hence different in
appearance from that of all the other rabbits of the region.
The jack rabbit is of slender build throughout. The
legs and feet are proportionately longer than in the cottontail and
brush rabbit. When foraging quietly, the jack rabbit moves by short
hops, keeping the soles of the hind feet on the ground and the long ears
erect (fig. 33). But when thoroughly frightened, as when closely pursued
by a hound, a coyote, or an eagle, the animal stretches out to the
utmost extent, the ears are laid down on the back, only the toes touch
the ground, and the body is carried low. In this position the rabbit
covers two to three yards at each bound. The jack rabbit's whole being
is modified for this sort of travel, for escape by speed in the
Only once did we find a jack rabbit taking shelter in
a hole, and that was a wounded animal. One shot near Lagrange lay
quietly on the ground until the collector made a move to pick it up.
Then the 'Jack' scrambled into a hole under some rim rock, whence it
could not be dislodged.
A typical meeting with a jack rabbit, near
Coulterville, is described in our notes of May 11, 1919.
One of these animals was started up in a hillside
field above the main road. He ran a short distance up the slope, then
stopped, standing first on the toes, then settled down until the soles
of the hind feet rested on the ground. I remained perfectly quiet for
several minutes and so did the rabbit. He stood in a quartering position
and eyed me monocularly. All this time the immense ears, appearing more
than twice the length of the head, were kept erect. I partially closed
my eyes and then noted how readily the rabbit melted into the
background, so that if it had not moved, it could easily have been
overlooked. Finally I started on and at once the Jack bounded off and
was lost to view behind some brush plants.
While we were camped along the shore of the Tuolumne
River below Lagrange in May of 1919, jack rabbits were often seen close
to the margin of the stream. Tracks and droppings indicated that they
frequented the place. Whether they came down (off the adjacent mesa) to
drink we were unable to ascertain. Their repeated occurrence close to
the river, where there was no particular sort of forage to attract them,
made this at least a possible explanation. Yet jack rabbits do live in
many places where there is no water at all to drink.
Fig. 33. Head of California Jack Rabbit,
one-half natural size. Compare with figs. 34 and 35.
The jack rabbit forages for a variety of materials,
including not only grasses but also parts of brushy plants. Where man
has taken possession of the country and planted alfalfa, grains, or
other crops these animals naturally turn to the new materials and often
take extensive toll. The erection of rabbit-proof fences and the killing
off of the animals by various means have been resorted to in efforts to
protect crops. In earlier years rabbit drives, participated in by all
the residents of a region, were held in attempts to reduce the numbers
of jack rabbits.
Seasonal fluctuations occur in the jack rabbit
population. In 1915 the numbers of the animals in the western part of
the Yosemite section were moderate, not great enough to excite comment
on the part of our field party. But in 1919 their numbers were notably
greater. On the hills about Lagrange an animal would be started up every
hundred yards or so. The rabbits were then common even through the
chaparral as far into the hills as Coulterville. In the vicinity of the
latter place individuals were come upon wherever there was any grass in
the small clearings. Rabbits, like meadow mice, sometimes increase until
they overrun the country, then suddenly decrease to a minimum. In
earlier years this was true of the jack rabbits in the lower San Joaquin
Valley, but since the great rabbit drives of the nineties, when
thousands were killed by the ranchers, this great variation in numbers
seems not to occur.
The young of the jack rabbit when born are far
advanced in their development as compared with the young of true
rabbits. The body is fully covered with hair and the eyes are open. The
body length at birth is about 6 inches and the animal weighs about 2
ounces. Growth is rapid and the young soon take on the rangy form of the
adult. Even in the very young the ears are large (about 2 inches long at
birth) and exceed the head in length so that no difficulty is
experienced in identifying them as young jack rabbits. In the cottontail
the ears are very short at birth, shorter than the head.
The breeding season of the jack rabbit extends
through most of the year, though a somewhat larger percentage of young
is produced in the spring than in other seasons. A female
(deserticola) taken at Mono Mills on June 19, 1916, contained 5
embryos. The average number in a litter, taking the country at large, is
between 4 and 5.