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6-8 Station 2: Beaver Dam
6-8 Station 2: Beaver Dam
Class discussion:
Why do beavers build dams?
Many people think that beavers build dams to live in-- but in fact, beavers build dams so that they can flood an area and create a safe place to build their homes, called lodges. Beavers want their lodges to be surrounded by water, so they build dams to create small ponds first.
Why do beavers prefer their lodges to be surrounded by water?
- Beavers surround their lodges with water for protection from predators. Beavers are not very fast-moving on land-- but they can swim very quickly in the water.
- Living in a lodge surrounded by water helps beavers gather food- they can easily and quickly swim to trees along the bank of their ponds, and can find aquatic plants along the bottom of the flooded areas they create.
A beaver lodge and surrounding pond provides a beaver with the necessities to live-- food, water, and shelter. What may happen if the ecosystem can not provide enough food, water, or shelter for a population of plants or animals?
Excess plants and animals will not be able to survive in an environment that can not provide food, water, and shelter. The term carrying capacity describes the maximum number of animals in a particular habitat that can be supported all at one time.
Natural of physical disturbances can also affect populations of plants and animals. What are possible examples of disturbances that can harm a population?
- Natural disturbances can include flood, drought, winter blizzards, etc.
- Physical disturbances can include pollution, deforestation, and destruction of habitat
In this image, the number individuals in the population is represented by water in the hose-- it continues to spray into the bucket
The bucket represents the ecosystem carrying capacity--when there are too many individuals, disturbances occur that reduce the number
Numerous disturbances are always occurring, and can affect more than one species of animal
Class Activity: Beaver Fever
Adapted from Project WILD
Materials: paper and pencil to record results
- This activity will be dealing with the three main necessities that all plants and animals need to survive: food, water, and habitat/shelter
- Divide students into groups of 4 by counting off; students who are 1's will move together in one area while the 2's, 3's, and 4's will make one large group separated from the 1's
- The 1's group will stand in a line facing down the trail, shoulder to shoulder
- The 2's, 3's, and 4's will walk 10-20 yards away and create another line, all facing the 1's
- The 1's group will play the Beavers. Every beaver will need to choose one necessity that it needs to survive-- beavers who need food will place their hands over their stomachs, beavers who are thirsty will place their hands over their mouths, and beavers who need shelter will place their hands over their heads.
- Beavers can only look for one necessity each round, but can change the necessity at the start of each round
- The group of 2's, 3's, and 4's will be representing food, water, and shelter. The students will choose which necessity they will represent and will use the same signs with their arms as the beavers.
- To start the round, both sides will turn their backs to each other and make the sign for the necessity they need/ are
- The instructor will call 'Go!' and the students will all turn to face each other, holding their sign
- Beavers will look for a necessity that matches their need, and will race to that necessity. Each beaver has to keep holding their sign until they reach the necessity on the other side.
- When they reach their necessity, they will tag that person and both students will return to the beaver side/start to become beavers for the next round (the beaver has successfully found its necessity and will survive to reproduce)
- If some beavers are unable to find their necessity, they will 'die' and become a necessity for the next round
- Keep track of the number of beavers that survive during each round for 10-15 rounds; discuss any trends at the end of the activity
- Activity Discussion:
- How did the population of beavers change as the number of necessities changed?
- At the start of the game, it was easier for beavers to find necessities- but as the beaver population increased, this became more difficult since the population was reaching its carrying capacity
- Do beavers need all of these necessities in order to survive?
- Yes, but they would not die instantly like in the game. In a real population, beavers who do not find their necessities may die from disease or starvation.
- What are animal populations constantly doing in order to survive?
- The populations are in a constant balancing act- always changing
- How did the population of beavers change as the number of necessities changed?
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