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All About Moose

Cows give birth to calves in late May when it is still cold and spring has not yet really arrived in the boreal forest. At this

time cow moose are malnourished and not yet recovered from the past winter’s ticks. It seems too early, but an early

start is essential so that calves are prepared to survive winter.

At birth calves weigh only 30 pounds, but can walk within hours of birth. For the first two months of life, much of the

calf’s nourishment comes from the mother’s milk. Calves begin testing different foods within a couple of weeks, and by

late July calves eat large amounts of vegetation. By late fall, calves are fully weaned. At this time, healthy calves weigh

300 pounds, almost ten times their birth weight.

For an entire year, calves depend on the protection of their mothers. A healthy mother is a formidable defense.

Typically, eight of every ten cows are pregnant each fall. By the following spring, twenty months later, only one or two of

every ten cows still have a surviving calf. By some standards the survival of a calf is miraculous; by any standard it is

against the odds.

Just before their first birthday, when cows are ready to give birth again, calves are rejected by their mothers. After being

with their mother for every moment of their lives, they begin a largely solitary existence.

While many cows are in the last months of pregnancy and raising a

young calf, bull moose begin re-growing antlers each spring. During peak

growth, antlers may grow three-quarters of an inch in a single day.

During summer bulls spend about 25% of their energy growing antlers.

This is energy that otherwise would have increased body reserves

necessary for surviving winter.

By Fall, antlers stop growing and bulls prepare to mate. So focused are

bulls at this time that they stop eating for a couple of weeks, and may

lose 100 or more pounds. They use their antlers to compete with other

males and attract females. Mating success is not guaranteed. Only healthy, experienced bulls mate. Success is

determined by antler size and symmetry.

In early winter, bulls shed their antlers. They face winter handicapped by the legacy of their antlers. If they survive, they

will begin growing new antlers in spring. Each year bulls grow larger antlers. They die shortly after old age makes it

impossible for larger antlers.

Antlers are extravagant and disposable sex symbols, like a young man in a hot sports car. Why spend so much on

antlers? It seems so wasteful.

Surviving the winter means nothing if doing so comes at the cost of not mating. Antlers are a sign of male fitness and

health, and are usefully thought of as a handicap. Only the fittest moose are able to devote substantial energy to antler

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growth. A moose in poor health is unable to grow large antlers, and in

this way antlers are an honest sign of a moose’s fitness.

Whereas cows may only give birth every other year, bulls nurture their

antlers every year. This intensity takes its toll. Compared to cow moose,

bulls have higher rates of osteoporosis and arthritis and shorter life

spans.

During summer, moose consume thirty to forty pounds of vegetation a

day. That would be like you or me eating 7 pounds of salad every day.

Because each bite may contain only a few grams of food, moose bite and chew several thousand times every day.

Moose patiently feed for about eight hours every day.

Moose forage is voluminous, but not very rich in nutrition. To accommodate this kind of food moose possess one of the

most complicated digestive systems ever created by Mother Nature (aka, natural selection). To get the most out of their

food, moose digest it a bit, regurgitate it, chew on the cud, and re-swallow it for a second round of digestion. Moose

patiently chew their cud about eight hours every day.

In preparation for winter, moose increase their body weight by as much as twenty-five percent. Imagine gaining twenty-

five percent of your body weight by eating only vegetable salads – no salad dressing, just the salad.

More than any other member of the deer family, moose spend time in

the water. The moose’s association with water is so distinctive that

moose may appropriately be considered the hippopotamus of the north

country.

Moose are well-suited for spending time in water. Long, strong legs allow

moose to walk easily in shallow waters and swim in deeper waters.

Moose also have large, complex noses. Of all members of the deer

family, moose have the biggest noses. The narial architecture of a

moose includes massive cartilage, specialized muscles, folded and

recessed skin, and fatty pads (see lower image). All these features may

represent a complex, nostril-closing system, that allow moose to forage underwater without breathing in any water.

Aquatic environments offer much to moose. Water brings coolness. In the water, moose reduce their respiration rate by

almost 30%, and their overall energy expenditure by about 10%. Water also brings nutrition. Of all the food that moose

consume, aquatic plants are the richest in protein and sodium. Water also brings safety. Even a weak, vulnerable

moose is considerably safer from an attacking wolf when standing in just a few feet of water.

For moose, winter is full of suffering and triumph over that suffering. It is not the cold. Moose are hardly bothered by

cold. It is the difficulty of getting food. During winter, moose mostly eat twigs from deciduous trees and shrubs and the

twigs and needles of balsam fir and cedar. Each bite of food is a mere gram – just 1/28th of an ounce. Moreover, twigs

and needles contain only one third the nutrition of leaves that moose eat during summer.

The fare is not only meager, but also difficult to gather. The snow is deep and moving from tree to tree is difficult and

energy consuming. Imagine yourself walking through chest or knee deep snow from tree to tree collecting about nine

thousand twigs – one twig at a time – every day. This is how moose – an 800 or 1000 pound creature – survive the

winter.

When snow is deep and foods sparse, moose restrict their intake of food because the costs of eating exceed the gains.

Moose pass much of the winter resting and ruminating, in solitude and hunger. Ultimately, moose lose weight every

single day, for about five months of every year. Nevertheless, most moose live to see the spring that follows each

winter.

One might rightfully think that moose are awe-inspiring for their adaptations to winter. Just as rightfully, one might also

think that winter is full of suffering and triumph over suffering. It is quite a powerful thing to give one’s attention to

another’s suffering and triumph.

Moose on Isle

Royale

from http://en.wikipedia.org/wiki/Wolves_and_moose_on_Isle_Royale

Moose health and population on Isle Royale have

a great effect on other animal and plant life.

Because of Isle Royale being an isolated island, neither wolves nor moose were there initially.

Moose swam across Lake Superior from Minnesota in the early 1900s. For nearly fifty years

the moose thrived, having no predator to dampen their population growth. In 1949 a pair of

wolves wandered across an ice bridge made to the island during a harsh winter

from Ontario. But because only one pair of wolves migrated to the island, inbreeding has

posed problems to the wolves' existence. According to Rolf Peterson, a professor at Michigan

Technological University and the lead wolf-moose researcher, "Moose were isolated here 100

years ago. Most of the genes are still here, but they have enough population (to compensate).

There are so few wolves that they have lost genetic variability. The scientific dogma suggests

that they are not going to make it. In fact, all of the wolves' DNA on Isle Royale can be traced

back to one ancestor. The lack of genetic variability leads to inbreeding, and inbreeding in

turn leads to mutations and fitness problems. Wolves with mutations often are violently

harassed, and sometimes killed because of their differences.

When initially studied in 1958, many researchers believed the two species would eventually

reach a population equilibrium (which is believed to be about twenty-five wolves, and 1,500

moose). They have not yet shown any sign of settling into one, instead tending to fluctuate

unpredictably. The highest number of moose on Isle Royale since being researched with the

interactions of wolves was 2,450 in 1995. The highest number of wolves ever recorded on the

island was fifty in 1980. The most dramatic decrease in the wolf population occurred when

the canine parvovirus was spread to the wolves on the island, introduced by a park visitor's

dog (breaking the rules of the national park) in 1980 or 1981, causing a crash in the

population; there were fifty wolves in 1980, but only fourteen by 1982. The population of the

two species as of 2005 was 540 moose, which is the lowest recorded, and thirty wolves,

which is considered rather high. In 2008, the number of moose was 700, and the number of

wolves were 23.

The density of the two species is very much dependent on the density of proper forage.

Because a moose's diet is 59% balsam fir, any change in its density affects the density of

moose. The consistent presence of moose on Isle Royale since 1900 has led to a dramatic

decline in understory growth of balsam fir. As of 2002, understory growth of balsam fir was at

5%, which is down 40% from 19th century rates, when it was recorded at 46%. The reliance

of moose on balsam fir has led to a much higher concentration of the species on the east side

of the island, where the plant is more plentiful. Birch and aspen trees, which are much

healthier for moose, used to grow plentifully on the island, but have now mainly been replaced

by the less nutritious balsam fir. Because balsam fir does not fulfill the amount of moisture

moose need in their diet, they have recently been spotted eating snow, which is a very rare

occurrence. They have also been sighted eating lichens, which is another very strange

occurrence; researcher Rolf Peterson has compared it to eating dust. When the moose

population grows too high, the balsam fir population crashes, which leads to a crash in the

moose population. This leads to the continuing "see-sawing" of the moose population on the

island. Crashes in balsam fir growth lead to malnutrition, which is one of the most common

killers, both directly and indirectly of moose. When there are too many moose for the amount

of balsam fir, then many moose, especially young moose become plagued with malnutrition,

which leads to arthritis. Moose commonly die either directly from malnutrition, or, because

they become emaciated, and slowed down by arthritis, they are picked out by a wolf pack as

easy prey, and are killed. The most common cause of malnutrition in moose is when calves

are born during a winter with deep enough snow that browsing for proper forage is very

difficult. The moose population should be able to rebound soon, because there are not as

many moose as there have been in the past, which will allow for the balsam fir to grow back.

Wolves use their intelligence to pick out easy moose prey, which they can outrun, and bring

down. They do not go after healthy moose, unless they are completely desperate; a healthy

moose in its prime years is very tough for any wolf pack to bring down. Also, moose in their

prime years commonly outrun wolves in a hunt; moose can cross snow two feet deep at

20 mph (32 km/h), faster than the best cross-country skiers, and outrun wolves if the snow is

soft. Even if wolves can catch up to a moose, they cannot always bring it down; researchers

have found many bruises and scars on wolves that have not been successful when trying to

kill healthy moose. Wolves pick out young moose calves, old moose, or moose plagued with

disease or injury in order to increase their chances in successfully killing one. The typical

moose that a wolf kills is about 12 years old, and suffers from arthritis, osteoporosis, or

peridontitis, and in some cases all of them. Though moose are often infected by various

diseases, approximately 80% to 90% of moose deaths on Isle Royale can be attributed to

wolves. The number of calves and old moose has declined recently, placing the future of the

wolves in doubt. Because moose make up nine-tenths of an Isle Royale wolf’s diet (the

remainder being snowshoe hare and beaver), finding a young, old or sickly moose is

imperative for survival. The average number of moose a wolf kills a month is between 0.44

and 1.69.

Small Creature, Big Influence

Blood-engorged, female tick after it has

fallen from a moose (above). With a blood

meal, it will now lay eggs in the soil - eggs

that will hatch next fall. The green are

balsam fir needles.

On Isle Royale, this creature survives by the blood

of moose and no other animal. Its existence

depends entirely on moose. It weighs only one

millionth the weight of a moose, and consumes

just a fraction of an ounce of blood during its

lifetime. This is Dermacentor albipictus, the

moose tick.

D. albipictus may cause as much if not more

suffering for moose than wolves or starvation.

Each winter, 80,000 ticks, or more, may live on

the skin of a single moose. Moose sacrifice gallons

of blood and much of their thick insulating fur to

give life to these horrific little creatures.

Winter ticks typically live only on members of the deer family and are found only

in North America. This tick species evolved with members of the deer family, like

white-tailed deer and elk. These members of the deer family have inhabited North

America for millions of years.

These members of the deer family are also

minimally impacted by winter tick. By contrast,

moose are new comers to North America. They

first came to North America about 10,000 years

ago. Because they are newcomers, they are not well

adapted to deal with winter tick.

The life cycle of winter ticks is also distinctive.

During the summer winter ticks exist only as

unhatched eggs in the soil. In autumn the ticks

hatch, crawl to the tops of grasses and wait to latch

onto any unsuspecting moose that walks by. These

young ticks feed and grow on the moose during the

winter. In early spring, the ticks mate, the males die

and the females drop from the moose to the soil

where they lay their eggs.

Ticks cause moose to lose their

hair throughout the winter (above).

Ticks can cause a heavily-infested

moose to die (above).

Ticks weaken moose and make them vulnerable to

starvation and wolf predation. At the turn of the

century we began to wonder, could D.

albipictus be a powerful influence on the

population dynamics of moose and consequently

wolves and the forest. To find out we had to

develop a way to quantify the level of tick

infestations each year. Here’s the method we

developed:

During the first five weeks of each summer field season, until mid-June, moose still

have their winter coats which are damaged from ticks. During this time we observe

hair-loss patterns on as many different moose as possible. Through binoculars, we

carefully observe moose. With cameras, we photograph them.

From these observations and photos, we draw patterns of hair loss onto data sheets.

We digitize these data sheets to estimate the proportion of hair lost on each moose.

Each spring we document hair loss patterns on 60 to 90 moose, which represents

about one out of every ten moose alive on the island.

It is a race against time, to see so many moose. Every year, within a few days of

June 18th, moose coats transform from sad-looking and tick-damaged to beautiful,

thick, and shiny, with no trace that they have ever been affected at all by ticks.

The first decade of monitoring (see graph at bottom left) suggests that high and

increasing levels of tick abundance may indeed play a role in cause moose

abundance to decline.

In this way, ticks seem to have an important influence on moose and consequently

wolves. The impacts don’t stop here. Ticks also affect much of Isle Royale’s

vegetation: The vegetation that moose prefer, various shrubs species and balsam

fir, have been exhibiting increased growth now that moose abundance is low. Ticks

appear to have a tremendous influence on much of Isle Royale’s community

through their impact on moose.

So, what factors determine tick abundance?

Warm springs, warm summers, and warm falls

are likely to favor ticks. Five of the past six

summers (2001-2006) have been the hottest

summers in the history of the project (1958-

2006).

The first decade of monitoring (see

graph above) suggests that high and

increasing levels of tick abundance

may indeed play a role in cause

moose abundance to decline.

What causes the climate to warm? An enormous

amount of scientific evidence indicates that our

use of petroleum causes climate warming.

It is reasonable to believe that humans, through

our excessive use of automobiles and other

fossil-fuel burning activities, are having a

profound impact on the balance of wolves and

moose on Isle Royale - an impact mediated by an

invertebrate the size of your fingernail.

The sad part of this story... This example of

climate change impact is in many respects minor

compared to other problems the climate change

are likely to cause - rising sea level, more severe

hurricanes, disrupted systems of food production

for humans, and the spread of diseases that

depend on warmer weather.

from: http://www.isleroyalewolf.org/node/44