PACIFIC NORTHWEST DRAGONFLY MIGRATION PROJECT
Advice for Teachers
Prepared by Terry Morse
Studying the fall dragonfly migration would be an excellent way to introduce your students
to scientific methods and techniques. They may experience both the thrill of contributing
original information and the challenge of figuring out how best to record and analyze
data. Noticing that a minor flight is occurring will both test and hone their powers of
observation.
One of the things you could do is to have several students independently determine the
number of dragonflies passing in a given period of time at the same location. Compare the
differences to measure "inter observer reliability": How much of the variation
in counts may be due to who is counting.
Does the direction you are facing affect your results? Suppose the flight is from north to
south and you are counting dragonflies in an open area, such as a sports field. Have one
group of students on the east side of the field facing west, and the other on the west
side facing east. Have both groups count dragonflies at the same time, for the same length
of time. (The students in a group will be counting individually, not as a group).
Determine the average and standard deviation of the count for each group, and then the
difference between the averages for the two groups. Is the difference in counts between
the groups about the same as the observer "error" (the standard deviation within
each group), or much larger or smaller? If the latter, then the difference between groups
is probably not due to the different membership of the two groups.
What might explain the differences between the groups? Was one group looking into the sun,
and one away from it? Might the backgrounds against which the groups were seeing the
dragonflies have made one group more likely to miss some of the dragonflies? All of these
are questions scientists must wrestle with in their research. If appropriate for the age
of your students, you could do formal statistical tests of whether the group counts differ
significantly.
With younger students who are likely to relate to the dragonflies emotionally, it might be
better to start them on a major flight, if one occurs this year. They may not have the
patience to stay interested in a flight where only two or three dragonflies pass in a
minute. Older students with an intellectual understanding of the exercise may be started
on minor flights. Explain to them that it is important to understand the differences
between flights, so minor flights are as important to investigate as major flights.
If you decide to take this on as a class project, both advance preparation and flexibility
are required. You never know for certain when a flight will occur or how major it will be,
so you need to have an idea of what you want to accomplish, then be prepared to implement
it on short notice when a flight occurs. Your first migration could be considered a
"pilot study," where you work out the logistics of your research design, finding
out what works and what needs to be improved upon.
THE OREGON DRAGONFLY AND DAMSELFLY SURVEY
