Biology 12

THINKING LAB

Sampling a Moose Population

Background

Knowing about the dispersion pattern typical of a species
and how this pattern can vary among populations can help
us understand the behaviour and ecology of the species.
It is also valuable to know about dispersion before taking
samples to estimate population density, since the accuracy
of your estimate can depend on the dispersion. In this lab,
you will see how transects might be used to sample
populations of a large mammal — the moose.

You Try It

1.Study the three diagrams showing hypothetical moose

populations with two different dispersion patterns.

Describe how the moose are dispersed in each diagram.

2.The shaded portions of the diagrams show the

transects that were used to sample each population.

What proportion of the total study area (defined by the

box) was sampled in each of the three cases?

3.Count the number of moose encountered within the

transect areasfor each case. (That is, do not count the

total number of moose in any of the diagrams.) From

these counts, estimate the size of the three moose

populations.

Dispersion pattern 2

4.The actual numbers of moose in the three populations

are 60, 133, and 133, respectively. How close were

your estimates? What do you think affected the

accuracy of the estimates in each case?

5.How would you design a sampling experiment on a wild

population? Note that in real life, the time and expense

involved usually restricts the proportion sampled to

between 10 and 20 percent of the total area of interest.

Dispersion pattern 1

Dispersion pattern 3

Chapter 14 Population Ecology • MHR 471

described as negative(that is, the individuals
repulse or repel each other). Such interactions
lead to uniform dispersion patterns.
For a population to display a random dispersion
pattern, the resources needed by its members have

to be uniformly distributed. These resources also

must be so abundant that there is no need for

individuals, pairs, or families to defend their share.

In addition, randomness requires that there be

neither positive nor negative interactions among