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  • caribou

    Elizabeth Curley (ecurley@mail.gbes.orange.k12.nc.us)
    Sat, 19 Apr 1997 09:48:09 +0000

    why do they migrate > USFWS
    > [Caribou] [Caribou]
    >
    > * Challenge Questions [Image]
    > * Caribou Field Data
    > * Journey North News
    > * Ask the Expert Caribou Migration Update: February
    > * Related Resources 6, 1997
    >
    > [Today's News] Robert Mulders
    > Today's News
    > Once again this season, [Image]
    > [Migrations and Signs of Spring]biologist Robert Mulders
    > Migrations and sends greetings and caribou data
    > Signs of Spring from his office near Hudson Bay in
    > the town of Arviat (Eskimo Point),
    > [Report Your Sightings] Northwest Territories. After reading
    > Report Your Sightings yesterday's manatee report from
    > Florida , one can't help but wonder
    > [Teacher Discussion] how welcome a warm water bath would
    > Teacher Discussion feel to a caribou. Conditions in the
    > arctic are extreme, and caribou have
    > [Search Journey North] amazing adaptations for survival.
    > Search Journey North Imagine roaming around on all fours
    > in temperatures at -45 degrees F,
    > return to: and spending several months in
    > [JNorth Home Page] almost constant darkness. This very
    > moment, while Ester, June, Cleburne
    > & company are basking in Ranger
    > [A/CPB Home] A/CPB Wayne's hotsprings, what do you
    > suppose our caribou are doing?
    >
    > After reading today's caribou data
    > (posted below) and locating the
    > caribou, see if you can answer this
    > Challenge Question:
    >
    > Challenge Question #1
    >
    > "What is the temperature
    > today for caribou # 6977?
    > (And for extra credit:
    > What is the photoperiod?)"
    >
    > To respond to this question please
    > follow the instructions at the end
    > of this report.
    >
    > In future updates, we will provide
    > sunrise/sunset data so you can watch
    > how dramatically photoperiod changes
    > in the arctic, and see how this
    > affects the lives of the caribou.
    > (Remember: "Photoperiod" refers to
    > the length of time there is
    > sunlight. You can figure the
    > photoperiod by counting the amount
    > of time between sunrise and sunset.)
    >
    > Click Here for Caribou Data
    >
    > For 8 months of the year, caribou
    > habitat is covered with snow. Snow
    > conditions influence where caribou
    > are able to travel, and the
    > availability of their food. With
    > their keen sense of smell, they can
    > find food even when its buried under
    > layers of snow. The caribou's
    > challenge is not only to survive the
    > winter, but to have the energy and
    > strength they will need for the
    > spring migration. Ironically, when
    > the snow finally begins to melt,
    > conditions can be worst of all. Snow
    > that melts on warm spring days can
    > re-freeze when temperatures drop,
    > making it impossible to dig for
    > food.
    >
    > The caribou's winter diet is
    > predominantly lichens. Lichens grow
    > very, very slowly. Because the
    > growing season is so short, it can
    > take several decades for a lichen to
    > grow a few inches. Then, in one
    > bite, it's gone! This helps explain
    > why caribou need so much room to
    > roam. After all, the food they eat
    > today will not grow back for many
    > years. In the arctic, life is strong
    > and fragile at the same time.
    >
    > Robert Mulders describes the
    > caribou's winter food:
    > "There are several hundred species
    > of lichens in this region. Caribou
    > are one of the few animals that can
    > eat this abundant plant because of
    > the acid it contains. Lichens are
    > high in carbohydrates and have the
    > most food value of any plant
    > available to the caribou. Lichens
    > are very, very slow growing. As a
    > rule of thumb, it can take 50-100
    > years for lichens to grow back. The
    > growing season in the arctic is
    > short--in some places as few as 40
    > days a year--and lichens grow only
    > around 1/16 of an inch per year. So
    > if an area is overgrazed or burned
    > the caribou won't be able to use
    > that habitat for many years. In
    > fact, there have been fires in
    > northern Manitoba within this herd's
    > winter range and we're concerned how
    > this might affect their use of the
    > area.
    >
    > "In the wintertime, caribou obtain
    > the lichens by 'cratering' through
    > the snow. When we go out for field
    > studies in late March we've seen
    > instances where they've cratered
    > through snow as much as 2 feet deep.
    > In most winters they can forage
    > without difficulty but some years
    > starving can occur if an icy cover
    > forms and prevents them from
    > obtaining food easily."
    >
    > Many lichens are very sensitive to
    > pollution in the air. When there are
    > too many harmful things in the air,
    > lichens die. This is why they are
    > sometimes called "indicator"
    > species. They can tell us if the air
    > is clear and clean. Even in the
    > remote arctic, pollution has
    > contaminated lichens. Pollutants
    > have drifted through the atmosphere,
    > appeared in the lichens, then in the
    > flesh of the caribou--and then in
    > the humans who eat the caribou.
    > Through studies of arctic women who
    > are nursing their babies, these
    > contaminants are known to even reach
    > babies when they drink their
    > mother's milk.
    >
    > How to Respond to Challenge Question
    > #1:
    >
    > 1. Address an E-mail message to:
    > jn-challenge-caribou@learner.org
    >
    > 2. In the Subject Line of your
    > message write: Challenge Question #1
    >
    > 3.In the body of the message, answer
    > this question:
    >
    > "What is the temperature
    > today for caribou # 6977?
    > (And for extra credit:
    > What is the photoperiod?)"
    >
    > Try this!
    > Write a vacation postcard from a
    > manatee to a caribou. Using today's
    > weather information, compare and
    > contrast the places these two
    > creatures inhabit. Be as descriptive
    > as you can. What does each animal
    > experience in the course of a day?
    > In what ways are your habitats
    > different? Are there any ways in
    > which they're the same?
    >
    > The Next Caribou Migration Update
    > Will be Posted on February 20, 1997.