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Title: Calculating Populations of Wild Animals
Principle(s) Investigated: The interaction of living things within their populations, communities, and ecosystems.
Standards : Grade-6
Ecology (Life Sciences)
- Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
- Students know populations of organisms can be categorized by the functions they serve in an ecosystem.
- Students know different kinds of organisms may play similar ecological roles in similar biomes.
Materials: Small paper lunch bag
Pinto beans
Permanent marker
Pencil
Procedure:
1. Use the table below to record your data..
2. Your teacher will provide you with a paper bag containing an unknown number of beans. Carefully reach into the bag, and remove a handful of beans.
3. Count the number of beans you have “captured.” Record this number in your data table under “Number of animals in first capture.”
4. Use the permanent marker to carefully mark each bean that you have just counted. Allow the marks to dry completely. When all the marks are dry, place the marked beans back into the bag.
5. Gently mix the beans in the bag so that the marks won’t rub off. Once again, reach into the bag. “Capture” and remove a handful of beans.
6. Count the number of beans in your “recapture.” Record this number in your data table under “Total number of animals in recapture.”
7. Count the beans in your recapture that have marks from the first capture. Record this number in your data table under “Number of marked animals in recapture.”
8. Calculate your estimation of the total number of beans in the bag by using the following equation:
total number of beans in recapture x total number of beans marked = calculated estimate of population
number of marked beans in recapture
Enter this number in your data table under “Calculated estimate of population.”
9. Place all the beans in the bag. Then empty the bag on your work table. Be careful that no beans escape! Count each bean as you place them one at a time back into the bag. Record the number in your data table under “Actual total population.”
Student prior knowledge: Students should know the definition of a population.
Explanation:
This experiment is a simulation of how populations in the wild are counted. The reason it's important to know the given population of an area is so that biologists can determine if animals are outgrowing their environment or are rare. It's often times difficult for animals to be counted due to the fact that they move around and hide. Most methods used by scientists to count a population of animals are only estimations. In addition, biologists study populations to determine what kind of organisms live in specific areas. When biologists find animals that are endangered or rare they takes steps to help protect these animals. The method biologists use to count populations of animals in the wild is called mark-recapture.
In this exercise, students are given the learning opportunity through a simulation experiment to experience the mark-recapture method use by biologists. The students engage in a cooperative learning process with their peers which includes pair share, data entry, and a calculation.
Questions & Answers:
How important is it to understand how communities work within a population?
Communities are comprised of all the populations that live in a given area. It's important to understand how they work together because populations depend on each other for food, shelter, and other things.
What would an ecologist study in a community made up of organisms in an abiotic environment?
An ecologist would be studying how organisms interact with each other and how temperature, precipitation, and soil characteristics affect the organisms. The flow of surrounding streams and rivers into a salt-marsh determine the nutrients that will determine the growth of cordgrass and algae growth.
Why do biologists study populations in the wild and what is the method they use to count populations?
Biologists study populations in the wild to find out if organism are outgrowing their environment or are endangered. The method they use to count populations within an area is called the mark-recapture method.
Applications to Everyday Life:
It's also important to know animal populations within a city environment. The reasoning is that an over population of an animal species within a city could cause problems. Depending where you live, an over population of some of the following animals could create harmful living conditions within a city: cats, dogs, coyotes, mice, rats, deer,and bear to name a few.
Not only is it important to know the population of animals within an area, it's important to know human populations. Cities also conduct a counting process of humans called a census. The city of Los Angeles conducts it's census every ten years. The purpose of the census is to estimate how many people live in the city of Los Angeles. The Census also helps the state determine how much money the city will need in the future and how many representatives to send to congress.
Photographs:
Videos:
References:
averysscienceclass.weebly.com/uploads/9/1/6/0/.../wild_bean_lab.doc
www.wildlifeextra.com/go/news/animal-counting345.html
… from capture data on closed animal populations - Otis - Cited by 1827
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… study of the animal population of certain submerged … - Krecker - Cited by 182
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