Animals of Arctic Tundra Regions

Much of the year, the Arctic (lowland) tundra is very cold. Tundra animals have physical and behavioral traits that help them survive and produce young in this harsh environment. Arctic tundra plants do not grow during the long winter months. So food is scarce. Animals living here must adapt their behavior in order to survive with limited or no food for long periods of time. Some animals avoid the long months of cold and lack of food by migrating to warmer environments with more food. Caribou migrate and spend the winter in southern forests. Many tundra fish even migrate to places where water remains liquid through the winter. Many tundra birds fly thousands of miles to areas in Central and South America. The Arctic tern migrates about 10,000 miles (16,000 km) to winter in Antarctica. This bird spends most of its life in daylight, living in the Arctic when it is daylight for several months, then flying to the Antarctic to stay for its daylight period.

Many tundra animals remain active during the winter by living under the snow and eating the buds, stems, and roots of dormant plants. Some, such as pikas and singing voles, also remain active under the snow layer and eat grasses and other plants they stored during the warm growing season.

Some animals survive by reducing their activities to a minimum. For example, the Arctic ground squirrel and marmots hibernate. A ground squirrel's normal body temperature of 97°F (36°C) drops to about 62°F (17°C) during hibernation. Its normal heart rate of 200 to 400 beats per minute drops to 7 to 10 beats per minute, and it breathes about 3 times per minute instead of its normal 60 times per minute. With a lower heart rate the squirrel needs only about 2 percent of its normal amount of energy. Hibernating animals store the needed energy as layers of fat, which are used by their bodies during the time they hibernate. During hibernation the squirrel doesn't eat or drink, instead its body uses the stored fat for energy.

Some animals, such as black and brown bears, reduce their activity during the cold winter by sleeping in a den (shelter for animals in nature) for several months. But these bears are not true hibernators. The difference is that the heart rate of a denning bear is reduced from about 50 to 60 beats per minute to about 20 beats, but its body temperature is not reduced. A brown bear weighing 300 pounds (136 kg) in the autumn may lose 100 pounds (45 kg) during its long winter nap. Bears wake up quickly if disturbed, but hibernating squirrels will not wake until their body temperature rises due to a change in the temperature of its environment.

Purpose

To determine your body mass index (BMI).

Materials

• calculator

Procedure

1. Determine your weight in kilograms by dividing your weight to the nearest pound by 2.2.

Example: If your weight is 88 pounds your weight in kilograms (kg) would be:

88 pounds ÷ 2.2 = 40 kg
2. Determine your height in meters by dividing your height in inches by 39.4.

Example: If your height is 53 inches your height in meters would be:

53 inches ÷ 39.4 = 1.35 m
3. Find you height in square meters by multiplying your height in meters by itself.

Example:

1.35 m × 1.35 m = 1.81 m²
4. Calculate your BMI by dividing your weight in kilograms (step 1) by the square of your height in square meters (step 3). Your BMI is the magnitude of this weight: height square ratio.
   

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