Introduction:
Surviving Winter

Animals rely on a combination of physical features and behaviors to respond to changes in the environments they inhabit. These features and behaviors—called adaptations—have evolved over time. While a fur coat is an obvious example of a physical adaptation for cold temperatures, what behavioral adaptations do animals exhibit to survive in winter?

The purpose of this activity is to show that organisms use a variety of strategies to help them survive when environmental conditions change.

Next: Responding to Changes Around You

To prepare yourself for thinking about how certain behaviors are important for survival, consider some of the different things you do when your environment changes.

For example, as seasons change from summer to fall to winter, you dress according to the cooler outdoor temperatures. By putting on a sweater or jacket before you go out, you help keep your body temperature within a particular range. This response keeps your body from becoming dangerously cold.

Of course, your body also has its own built-in response to changes in the external environment. To keep from getting too cold, your body shivers, which is an involuntary, or automatic, response. While dressing warmly can be considered a learned behavior, shivering is a genetic behavior.

How do humans respond to these environmental conditions?

• bright sunshine
• hot temperature
• chilly breeze

Write down as many learned or genetic behavioral responses that come to mind for each condition. Click "save notes" before moving on to the next page.

Next: Migration: Watch This!

When faced with challenging conditions, some animals simply get up and move away for a time. This is called migration, which is relocating from one habitat to another where survival is easier.

Each winter, shorter days and falling temperatures cue migrating animals to seek milder weather and a secure food supply. This includes species of birds, fish, insects, and mammals. The longer the migration, the greater a physical toll it can take. Animals may die from exhaustion on their journey. Other migration hazards include difficult weather conditions in transit, exposure to disease, and predators.

Watch this video segment about a butterfly that migrates in great numbers from the U.S. to Mexico. As you watch, you will learn why monarchs leave their warm-weather habitats to face a challenging journey. In the box below, list three to five important ideas that you learned about migration.

Note: You will hear the following words in the video segment. Click on each word to see its definition.

• autumnal equinox
• chrysalis
• colonies
• homing instinct
• pupae

Write your text in the box below, then click "save notes" before moving on to the next page.

Next: Hibernation: Watch This!

Some animals seek a sheltered place where they hibernate (or sleep through) the coldest part of the year. Hibernating animals survive their prolonged period of inactivity on stored fat. A hibernating animal such as a bear can only sleep as long as these fat reserves last. If it wakes early and food remains scarce, it will likely starve and die.

When it resumes activity, a hibernating animal can be severely weakened, having lost a great deal of weight and muscle from starvation and inactivity. It may be several days before it recovers enough strength to search for food.

One type of frog hibernates in an unusual way, using an adaptation called freeze tolerance. Freeze tolerance is the ability to freeze solid in extremely cold temperatures and then thaw when it warms, with no known harmful effects. Watch this video segment to learn more about this unique twist on hibernation.

Note: You will hear the following words in the video segment. Click on each word to see its definition.

• antifreeze
• blood sugar
• camouflaged
• flatline
• spontaneous resumption of function
• synchrony

Next: Remaining Active

In contrast to hibernation, some animals remain active during the winter. These animals undergo a bodily change in response to the changing conditions. Most of these changes help conserve heat and energy.

For example, an animal may thicken its hairy coat or produce a special type of fat that generates heat inside the body. An animal may also modify its diet, slow its metabolism, or sleep in groups.

Even though remaining active in winter keeps an animal in its home range, it may have to expand its hunting or foraging range to find food. If snowfall is heavy, additional energy must be expended, which can make survival an even greater challenge.

Next: Try This!

As you saw and read on the previous screens, different animals respond in different ways to the changing conditions around them. In this activity, you will place statements about winter survival behaviors into one of three categories. Then, draw connections between related behaviors and note any similarities or differences. For example, connect and compare the different ways in which animals that migrate find food compared with those that remain active. (Complete directions for how to do this appear in the Flash Interactive activity.)

Click "View" on the left to begin the activity. Be sure to print your notes before you exit the activity. Your notes will not be saved.

If you want, you can watch the videos again.

Migration of the Monarchs

QuickTime Video
Length: 2m 60s

Frozen Frogs

QuickTime Video
Length: 3m 31s

Next: Did You Know?

You've already learned how many different animals adopt different behaviors to survive each winter. Here are examples of physical adaptations that certain animals have evolved that support these behaviors.

• As winter approaches and the days shorten, migrating birds gorge on food to add fat to their bodies. The more fat they have in reserve, the fewer stops they'll need to make. This reduces their vulnerability to predators.
• A bear's digestive system is adapted to recycle its waste products during hibernation. While most hibernators waken periodically during winter, a bear won’t rouse itself—not even for a "bathroom break."
• A bumblebee shivers its flight muscles to prepare for flight in cold weather. This generates heat, which then gets trapped in its fur.
• An alpine bird called the willow ptarmigan grows feathers on the soles of its feet in winter. These feathers provide added warmth and act like snowshoes that keep the bird from sinking into the snow.
• The white winter coat of the Arctic fox not only conceals it from predators or potential prey, it also provides added warmth. Lacking pigment, the hairs are hollow and act as insulators.

Next: Read and Write About It!

You have been introduced to the three main winter behaviors that animals exhibit. Now you will have the chance to read about each of these behaviors in greater detail. Then you will share your ideas with others.

• Print out your notes. (After you print, your notes will be erased. Make sure you are done before printing.)
  
  
• Print out and read Winter Survival Strategies (Version A) (PDF) or Winter Survival Strategies (Version B) (PDF). Check with your teacher if you are not sure which version to use.
• After reading, take a look at your chart and make any changes or add new information.
• Then, select a writing assignment from page 2 of the printout.

Note: The following words will appear in the version B reading. Click on each word to see its definition.

• metabolism
• protein synthesis