Herbivory in action
The Roosevelt elk are strictly herbivores with a digestive
system that can handle many of the grasses and vegetation that is
commonly found in its habitat. The habitat
that the elk resides in is mainly the pacific rain forests but
there can be many other places it can be found
where in every winter is a lack of vegetation. It has
been observed that during the winter the elk don’t eat when
there is snow on the ground, but that once the snow has melted
the elk eat exclusively until either they run out of food or
there is once again a layer of snow. This can cause some
problems with the elk and in some instances the elk can go
hungry in the winter months for prolong periods of time(Murie
1951).
The elk has adaptations that help it acquire its food. These adaptations include the well-developed digestive system that includes 4 stomachs and a long intestinal tract that allow it to absorb as many nutrients that it can while it still has the organic material in its body. These nutrients help it fuel its body and fight the sometimes bitterly cold temperature, with the help of its thick winter coat as well. After the nutrients are digested they continue into the closed circulatory system that Roosevelt elk have. This allows the elk to move faster than organisms with an open circulatory system and also allows them to regulate their bodies with more control than organisms with an open circulatory system.
The elk stores excess food as fat. They tap into the fat stores during winter when there is not enough food to survive off of. This causes some problems during after the rut when some bulls are not able to survive because their long term fat stores were diminished because of the mating season. There have been some bulls that have died in the winter because of diminished fats reserves and lack of food.
When the elk does have food available here are some common types
of vegetation their diet consists of (Murie 1951):
Genus:
Acer
(Maple trees): This is a common plant that is
consumed by the Roosevelt elk. These trees and shrubs are found
in extensively in the Olympic Mountains. The elk feed off of the
leaves that these plants produce. This is one of the major food
sources for the elk because they are plentiful within their habitat
and readily accessible. Another advantage is the elk cannot reach
the hind limbs so the tree will never be killed because of the
feeding of elk. During some heavy snow falls the limbs that are
usually out of reach for the elk can be bent downwards so as they
become available for the elk to feed off of. The major problem with
Maple trees is that the elk can
become injured when eating if a splinter is lodged in its
tongue. Usually in the winter the elk will eat the twigs of the
maple, but in the spring and summer it will eat the leaves of
the trees. Also during large storms the limbs of trees will
periodically fall down. When a limb falls down the limb is stripped
of all of its bark and twigs by the Roosevelt elk. The stomach of a
Roosevelt elk was opened to reveal the contents being 99% vine maple
mixed with big leaf maple(Murie 1951).This only shows how dependent on different types of
maples the Roosevelt elk is.
Alnus rubia (Red Alder): This is a plant that is mainly consumed
in the winter(Harper 1967). Usually the elk will strip the bark and twigs off
of the limbs much like it did with the maple. In the spring the
elk will mainly devour the leaves of the tree with the twigs
being saved once the leaves are gone.
Gaultheria shallon (Salal): Most of the Salal is unevenly
distributed throughout most of the habitats the Roosevelt elk
primarily lives in(Murie 1951). Although this is the case, sometimes when
present the Salal is abundant in these habitats. The elk eats
mainly eats the leaves of this shrub. This is not a major food
that the elk eats but it is commonly found within the stomach of
the elk.
Pseudotsuga taxifolia (Douglas-fir): This is one of the more
attractive foods that the elk has access to. This is not readily
available to the elk so there are some complications that arise
when comparing it to the amount that an elk will actually eat(Murie
1951).
This is still a popular food item when the elk has this present;
it will devour all of the Douglas-fir it can find.
Rubus macropetalus (Blackberry): On the Blackberry, mostly the
twigs and vine are consumed. Although they are commonly found in
the Olympic Peninsula a large herd of elk that once lived there
no longer browses the setting(Murie 1951). The vines of the blackberry are
also eaten in the California region that the Roosevelt elk
resides in.
Vacinium. Blueberry: There are four different species of
blueberry that are commonly eaten by the elk: Vacinium
parvifolium, Vacinium ovalifolium, Actinium
membranceum,
Vacinium ovatum(Murie 1951). Some of these berries are actually abundant
during the winter. These are thought to be the most appealing
vegetation that the elk consistently eats. There have been some
plants that have died because there had been too much feeding
per plant that there were not enough leaves to continue making
energy through photosynthesis.
Mushrooms:
The Roosevelt elk have been documented to have been eating different
types of mushrooms(Murie 1951)
These mushrooms were never identified so the specific species of
mushroom remains unknown but it is still interesting that the
elk have used mushrooms as a food source.
Rotten Wood: Yes, evidence has led to the conclusion that
Roosevelt elk do eat rotten wood. The main types of wood that
they eat are: Hemlock and maple. To actually eat the wood the
elk would dig a small tunnel below the wood and actually eat the
wood from the bottom up. The reason why the elk prefers to eat
the underside of rotten wood and also why they eat rotten wood
are both unknown. The actual nutritional contents of rotten wood
are not considerably large
although there are still some concentrations of nutrients
available(Murie 1951).
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