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Dusky-footed woodrat
The dusky-footed wood rat, although found on hillsides, usually
select valleys and lives very close to small streams and water.
Since this species likes areas that are covered, they tend to avoid
open grassland and open oak woods with small amounts of underbrush.
The plant species in the area affect the wood rat through the nature
of the cover and screening it offers. Plants such as Arroyo Willow,
Red Willow, and Coast Live Oak provide good protection.
Besides the biotic features of a habitat, there are also abiotic
features which contribute to the nature of the dusky-footed wood
rats' habitat. Light is avoided even when it is as weak as
moonlight. Cold air is more suitable than extreme heat. When
temperatures approach one hundred degrees Fahrenheit, wood rats move
to cooler places. Dryness of a wood rat's coat is important for
maintaining good health, but low humidity is unfavorable. Within
their habitats, rats live in colonies of three to fifteen or more
nests (homes).
The fundamental pelage color of dusky-footed wood rats is cinnamon
with variations toward tints of buff and pink. Every dusky-footed
wood rat has vibrissae (whiskers) that are disposed in six parallel,
evenly spaced rows. The ears are thin, large, rounded, and broad as
well as hairy. The claws are short, sharp, curved sharply downward
and almost equal in length. The claws are also colorless. There is
some sexual dimorphism in this species. Females are about 38.5cm in
length (including the 18.7cm tail). Males are about 44.3cm
(including a 21.5cm tail). Males usually also weigh more than
females.
Reproduction
Reproduction by a male dusky-footed wood rat depends on its
proximity to other male conspecifics. In the presence of many male
rats, individual male rats may not reach full sexual maturity or
physical size. However, when a male wood rat is isolated it
immediately increases its weight and becomes sexually mature. At
this time, the testes increase in size dramatically.
The reproductive period of this species usually begins in late
September and continues until mid-June or mid-July. This coincides
with the onset of the rainy season and the growth of plants. The
inactive reproductive period arrives in the dry season when much of
the vegetation is not growing.
Females also show seasonal changes in reproductive activity. The
months of April and May are when most females are reproductively
active. Females mate with a single male, and there is no evidence of
polygamy. During the breeding season, males move about changing
nests in search of sexually receptive females. Males pair with the
most accessible female, which is usually the one closest to their
nests. The fewer females present in an area, the more a male will
move.
Females remain in their original nests and may raise a succession of
litters. Some females may experience reoccurring estrous cycles
without becoming pregnant. This occurs when there are fewer males
than females in an area, and each of these males limits its
attention to a single female. The result is that some females are
without a male for a long time.
Once gestation begins, the female is intolerant toward the male and
sometimes will attack the male. If a male approaches an intolerant
female, and if he has not mated yet, he will leave the vicinity and
find another receptive female. Once a male mates, he lives alone in
a separate nest which he builds himself. By spring, most females
begin producing young. The suckling young, about 2.8 per litter, are
dependent to the mother until the time of weaning. Weaning begins
three weeks after the young are born. After weaning, the young begin
to eat the same greens as their parents. Females protect suckling
young by hovering over them and attempting to bite an animal who
tries to touch them.
Behavior
The dusky-footed wood rat is a nocturnal animal, although some have
been observed during the daytime. Individual wood rats vary in the
times they become active in the evening. The time of the day, the
season of the year, and the weather determine the length of time of
activity.
The posture of a wood rat indicates the feeling or mood of an
individual of the species. When a dusky-footed wood rat sits quietly
but on alert, the hind feet and one or both forefeet bear the weight
while one or both forepaws may be raised against the breast with the
paw flexed. The tail is sometimes extended over the more or less
humped back. When annoyed, angered, or fighting, a dusky-footed wood
rat pulls its ears back.
Sometimes males fight when they encounter each other. Usually, one
male rushes at the other and bites his opponent. They both beat
their tails against the ground and open and shut their mouths. Face
washing is characteristically seen following a disturbance, but only
when the rat feels safe. Tooth chattering and biting are used
against and by intolerant conspecifics.
It is more common, however, for members of this species to be
tolerant of one another. Friendliness between individuals, both
males and females, is usually seen when they live in adjacent
houses.
Locomotion is another behavior studied by scientists. It was found
that this species travels equally well through bushes and trees and
over ground, as long as the path is free of impediment close to the
surface. However, they need a path with overhead cover. When a wood
rat travels across leaves, it walks slowly, lifting one leg at a
time. In contrast, it will run across branches. This difference in
locomotion probably occurs because running across leaves causes a
crackling noise which may attract predators.
When a dusky-footed wood rat runs, its tail is normally held
straight out behind and parallel with its substratum. It has also
been observed that rats use their tails as a warning device against
predators.
Although males travel among different houses looking for a mate,
they eventually find a mate and live in a permanent residence. As a
result, this species has well-developed sanitation habits. Excrement
is carefully kept from their homes. Some wastes do accumulate in
the house, but they are placed in areas that do not interfere with
continuous living in the house.
Dust bathing is a common practice of the dusky-footed wood rat. This
process involves spreading the four legs and drawing and pushing the
abdomen against the dry soil. After this process, according to one
scientists observation, the rats seem to be relaxed. Fecal matter
was found in the area, and this may explain why the wood rats push
their abdomens against the soil.
Dusky-footed wood rats also lick their pelage for cleanliness.
Analyzing the behavior of captive rats has proved to be difficult
because only fleeting glimpses are seen of certain aspects of
behavior. Therefore, many observations of wood-rat behavior have
been made on captive wood rats.
Wood rats prefer using trees, branches and limbs to travel. Among
trees, the dusky-footed wood rat uses a ground trail or route. These
trails eliminate uncertainty about where to go when the wood rat is
being pursued by an attacker, and they also provide a quieter path
over what could be a litter-strewn area. The trail will not have any
obstacles on it, and often represents a straight line connecting two
sites of rat activity. These trails are maintained both accidentally
through use and deliberately.
Food Habits
The dusky-footed wood rat feeds on seventy-two different types of
plants. Some of these include Blackberry, Maul Oak, Valley Oak, Soap
plant, Gold fern, and Bracken. This was determined by analyzing food
specimens in homes of dusky-tailed wood rats. The plants consumed by
the dusky-footed wood rat are utilized for nutrients as well as
their water content. This species derives moisture from eating the
vegetation. However, the availability of certain plants varies with
the seasons. This species has a tendency to store a large amount of
food in its nests. In one nest, for example, there were one hundred
and thirty-two cuttings of fresh material. The dusky-tailed wood rat
eats food throughout the night. In one feeding period, they consumed
44.2g on average. In captivity they should be offered a complete diet
of rodent lab blocks, and rat or mouse
mix, with bits of fruit or veggies regularly. Cheerios or wheat
bread are great treats, in small quantities. Do NOT feed chocolate,
fried foods, salted foods, candy or junk food! They may enjoy
crickets and mealworms if they are captive bred, never feed wild
insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium
during nursing and growth due to demands on their systems at those
times, but take care not to overdo it. Water bottles should be used
to proved constant, clean water. Ceramic or stoneware food dishes
work well for keeping seeds or fresh foods off the floor, and a wire
mesh hopper that allows them to eat the lab blocks through without
extra waste.
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