Caribou Caribou
  • Challenge Questions
  • Caribou Field Data
  • Journey North News
  • Ask the Expert
  • Related Resources

    Today's News
    Today's News

    Migrations and Signs of Spring
    Migrations and
    Signs of Spring

    Report Your Sightings
    Report Your Sightings

    Teacher Discussion
    Teacher Discussion

    Search Journey North
    Search Journey North

    return to:
    JNorth Home Page

    A/CPB Home A/CPB

  • caribou

    Elizabeth Curley (
    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:
    > 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.