Scientists at Work

The Great Elephant Census Student Worksheet

8. Apply what you learned from the film:

The Great Elephant Census involved over 100

scientists working in many countries. Within

each country, they divided survey areas into

regions, called strata, of varying shapes and

sizes. Teams then flew along transect lines to

estimate the number of elephants in each

stratum. The lines in the diagram to the left

represent the transects that a plane follows

during an aerial survey of each stratum. The

counting strips are 150-m-wide areas on either

side of each transect where elephants are

counted. The table below shows the data that

were collected for one stratum.

Width of

counting strip

(km)

Counting

strip area

(km

2

)

# of elephants

spotted in counting

strips

Elephant density

in counting strip

(#/km

2

)

Average Elephant Density for Stratum (round to nearest hundredth)

a. Calculate the missing values in the data table. Here are a few formulas to help you out …

Area = length × width Population Density = # of animals/area

Average = sum of all of the densities/# of transects

b. The total stratum area is 803.7 km

2

. Using the mean elephant density for the stratum that you

calculated, calculate an estimated # of elephants that could be found in this stratum.

c. What might explain the wide range of elephant densities among the different transects of the stratum?

Give two reasons, one that relates to elephant behavior and one that relates to the survey design.

Revised September 2017