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Challenges of Field Biology
Duration: 45min. - 1 hour
Grade: 4th - 8th
Goal:
Through a simulation activity students will discover some
of the difficulties that researchers face when trying
to study and count wild populations. These challenges
have led to the development of remote sensing techniques.
Objective: Students will be able
to…
· Identify different censusing (counting) techniques
· Discuss why censusing is necessary
Standards:
English/Language Arts: A-1, A-2, A-3, A-4, C-1, C-2, C-3,
D-3, D-4
Mathematics: A-2, A-3, A-6, B-6, B-7, D-1, D-2, E-1, E-2,
E-3
Science: A-14, A-15, B-2, B-3, C-1,
Geography: A-1, A-2, A-3, B-1, B-2
Materials:
· One-quart jar of kidney, pinto and navy beans
(equal amounts of each)
· Counting mask made of a piece of paper with a
2"x 2" square hole cut out of it.
· Maps and charts of the Alaskan coast line
Background:
Counting the number of animals in a wild population is
often nearly impossible, especially for species with large
numbers and species that spend much of their time in the
water. To better understand individual species and populations,
scientists estimate the numbers of animals through observation.
If serious declines are reported, biologists identify
areas of concern and make detailed counts. The information
obtained from these counts help resource managers make
the appropriate decisions for species protection.
Researchers make visual observations, take
photographs of a known number of animals at various densities,
and practice making estimates by using computer generated
exercises. Mistakes can occur when estimating populations.
"Bias" often occurs because characteristics
of a population may cause it to regularly be over or under
represented. For example, in estimating the number of
seals at or near haul out sites, the estimate would favor
larger animals, hauled out of the water, with a lighter
color pelage (hair or fur). Observer variability, also
known as "counting error" may also cause mistakes
in estimating population.
Activity:
Before the activity, set up three "haul-out sites"
using the beans. Beans may be mixed to represent color
variations within the population. Place these on three
separate tables or desks. Each group can contain a different
number of beans. Group 1 should be uniform (all pretty
much in one area), Group 2 should have an area of heavy
density (lots of beans together) and an area of low density
(beans more widely spaced), and Group 3 should be assembled
on white paper. Place a barrier in front of the beans
or have students wait in another part of the room until
it's time to make their counts.
Divide students into "research teams"
of 5-6 people to do their estimates. Have students stand
approximately 10 feet away from the beans. They should
take approximately 20 seconds to estimate the number of
"animals" in Group 1.
· How many beans make up the estimated
total population of Group 1?
· How many of each type of bean (pinto, navy, and
kidney) makes up the colony?
Biologists normally count a small group
of animals and then estimate how many groups of that size
make up the total group. Place a counting mask over a
section of Group 1. Allow students 20 seconds to estimate
the number of beans in the colony using this technique.
Have the students compare these results to their first
count. Try this technique on Group 2. Explain that Group
2 represents a haul-out site with two different densities
of seals (perhaps a high concentration are feeding in
the water and a few are hauled out on the rocks). Students
may find that doing two separate counts with the counting
mask to sample from both the low density and high-density
areas will help them make a more accurate estimate after
they average the counts.
Students should now look at Group 3. What
effect does placing white paper under the beans have?
(It is now easier to see the kidney and pinto beans, but
difficult to see the white navy beans.) How does this
relate to looking at seals in the wild? (Dark colored
seals may rest on dark rocks.)
· What problems could occur when making estimates?
How does bias affect a count? Example: We may over estimate
the species that are easy to see, but may under estimate
species that are difficult to see.
· What are some of the difficulties in counting
a population? Why do biologists want to count populations?
What are other ways that scientists can track animals
in the wild?
Extension activities:
Generally, pinnipeds like seals and sea lions are counted
at haul-out sites and rookeries. Aerial surveys, boat
surveys and remote sensor surveys are all methods employed
in observing these animals.
1. Using charts, maps, Internet and other
resources, list some of the marine animals that live in
Alaskan waters and whose populations are counted or "censused."
Identify these animals, locate where they are found on
the charts / maps and present this information to the
class. Describe some of the difficulties associated with
observing these animals and subsequently managing their
populations.
2. Research the cost of counting wild populations of animals.
Include transportation, salary, equipment, etc. Write
a proposal for a research project to observe a certain
population on marine animals. Include maps / charts of
the area that your are proposing to do your observations.
3. What impact can scientists have on animals in the field
when they are making observations? What methods may be
used to avoid these problems? Write an essay describing
these impacts and suggest ways to avoid them.
Challenges of Field Biology
Worksheet
Group 1 - consistent distribution
# pinto beans # navy beans # kidney beans Estimated total
Estimate 1Stand approximately 10 feet from the "population"
and count for 20 seconds.
Estimate 2 Place the "counting mask" over a
section of Group 1. Count for 20 seconds. Trial A
Trial B
Avg. (A+B)¸2
Group 2 - varying density # pinto beans # navy
beans # kidney beans Estimated total
Estimate 1Stand approximately 10 feet from the "population"
and count for 20 seconds.
Estimate 2 Place the "counting mask" over a
section of Group 2. Count for 20 seconds. Trial A
Trial B
Avg.(A+B)¸2
Group 3 - white background # pinto beans # navy
beans # kidney beans Estimated total
Estimate 1Stand approximately 10 feet from the "population"
and count for 20 seconds.
Estimate 2 Place the "counting mask" over a
section of Group 3. Count for 20 seconds. Trial A
Trial B
Avg.(A+B)¸2
Follow-up Questions:
Actual number of beans in Group 1? ____________
Group 2? ____________
Group 3? ____________
1. Which counting method was the most accurate?
2. What problems could occur when making
estimates?
3. What are some of the difficulties in
counting a population?
4. Why do biologists want to count animal
populations?
5. What are other ways that scientists can
track animals in the wild?
