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, etc.

The disturbances and other limiting factors determine the carrying capacity of a population.

What limiting factors could be influenced by the population size?

Competition for food, Predation, Parasitism and disease are all examples of limiting factors that are caused by the population size; these are called density-dependent

What limiting factors are not influenced by the population size?

Unusual weather, natural disasters, pollution, deforestation, destruction of habitat, etc. are examples of limiting factors that are not caused by the population size; these are called density-independent

What would happen to populations that are unable to grow due to disturbances or limiting factors?

These species could be considered Endangered or Threatened, and could become extinct if population size continually decreases over time. Endangered and Threatened species are protected by federal laws. Scientists will develop wildlife Recovery Plans to attempt to reintroduce or recover a population.

Class Activity: Back from the Brink

Adapted from Project WILD

Materials: paper and pencils (optional), copies of the background sheets for North American alligator, black-footed ferret, and the gray wolf (https://drive.google.com/open?id=1BRq43y577bLW90ieS2LtKFM877SNvIaM ), Issue Analysis half-poster (https://drive.google.com/open?id=1CnZaW5xAbW8SCBBUn23rJp2UbPe4RErOtDyTu2rVO4g )

• In this activity, students will split into groups and read about the recovery efforts of three different endangered wildlife species (option to read about one species aloud as a class)
  • While reading, students should consider these questions:
    • About the animal species-- what is the:
      • Preferred habitat, Food, Historic Range, Current Range, and Current Status
    • About Decline and Recovery-- what is the:
      • Major reason(s) for the decline of this species
      • Events, changes, or laws that occurred to enable recovery
• Each group will share what they have learned about their endangered animal with the rest of the class
• Connections Close to Home--
  • The Gopher Tortoise is a very important member of the longleaf pine ecosystem, which at one point covered a majority of Southern Georgia, Alabama, and Florida.
  • Due to habitat destruction and predation, gopher tortoise populations are considered threatened in the Southeast US.
  • Gopher Tortoises are a keystone species, meaning that many other species depend on the gopher tortoise for survival-- burrows dug by gopher tortoises provide habitat to over 350 other animal species!
  • See the 2 min video below for more information on Gopher Tortoise recovery!