Download Snake Field Trip Experience

SNAKE FIELD TRIP EXPERIENCE
THE USE OF OBSERVATIONAL STUDIES IN SCIENCE
OBJECTIVES
In this experience, you will endeavor to achieve the following objectives:
1.
2.
3.
4.
5.
6.
Explore the potential of observational studies in sciences
Develop two observational studies in ecology, behavior and morphology
Become familiar with dispersion patterns of organisms
Witness antipredator behaviors of several snake species
Correlate antipredator behaviors with morphological adaptations
Handle data collection and data handling to answer biological questions
BACKGROUND:
Observational studies are a powerful tool to start collecting evidence in science. Today, we will
explore the potential of observational studies in examining the ecology and behavior of several
snake species on Beaver Island.
Before any field trips involving data collection, students should be familiar with the natural
history of the organisms being observed. In our case, we will watch a video and go over a
couple of PowerPoint slides explaining the main biological concept covered in this field
experience. These concepts are briefly described below as a future reference.
BIOLOGICAL CONCEPTS:
Patterns of dispersion: a key concept in ecology (the study of populations’ in their
environments) is the distribution of organisms in their environment. Organisms can be
dispersed randomly, just as many plant species that grow where their seeds were dropped,
nearly regular, typically due to some negative interactions with neighbors such as in many crab
species on a beach, or clumped, typically due to some positive interactions with neighbors.
Understanding the dispersion of organisms is critical to developing management plans for any
species.
Antipredator behaviors often involve particular morphological traits such as body surface shape
and coloration. Sometimes they involve physiological traits such as the production of venoms or
noxious smells. These morphological or physiological traits are tightly linked with behavioral
adaptations; for instance, blending into the background may require staying motionlessness
and the effective use of noxious smells may involve decisions of when to release them. Success
at evading predators can thus be dependent on these correlations between behaviors and
morphological or physiological traits.
ORGANISMS OF INTEREST:
We will be going to Miller’s marsh, a property of CMU located in the south west part of Beaver
Island. The marsh provides an ideal habitat for snakes and is the home to 7 different snake
species, none venomous, out of the 8 species present on the island.
Dr. Gillingham, a retired professor of Biology from CMU, described the snakes as following:
Of the eight species of snakes found in the Beaver Island archipelago, the largest by weight is
the Northern water snake while the largest by length is the Eastern milk snake. The smallest
are the red-bellied snake and its close relative, the northern brown snake. The smooth green
snake is totally insectivorous and an egg-layer with one of the shortest incubation periods of
any North American snakes: nine days. The Eastern ringneck snake is very aptly named with a
well-defined ring around its neck, and feeds on salamanders. The Eastern garter snake is the
most abundant snake in the archipelago, and feeds on a wide variety of food, from earthworms
to small mammals. The Northern ribbon snake, very similar in appearance to the garter snake,
is much more slender, with a longer tail. It feeds primarily on amphibians.
Below are pictures of all 7 species you are likely to see.
Garter snake
Garter snake
Ribbon snake
Ringneck snake
Ribbon snake
Red-bellied snake
milk snake
Brown snake
Smooth green snake
DEVELOPING THE RATIONALE FOR THE STUDIES:
Today, we will be collecting data on two different aspects of snake biology: their ecological
dispersion, and whether their escape behavior is linked to their morphology, as theory would
predict.
Before heading for the field, brainstorm in groups of 3-4 what you would predict would happen.
What type of dispersion pattern should we find? Would it be similar for all species? Why or why
not? Similarly, what are ways that snakes may escape their predators once detected? Would
certain body patterns help or deter these escape behaviors? How would you predict snakes to
avoid their predators based on their body patterns? What resources can we use to make a
guess? How can students locate these resources?
For each of the 7 snakes you might see at the marsh, we will gather predictions as a group
regarding which ecological dispersal patterns we expect each snake species to have, and which
escape behavior snakes are most likely to adopt based on their body coloration.
We will test these predictions in the field.
FIELD ACTIVITY:
Miller’s marsh contains a large number of wooden boards under which snakes like to rest.
Today, we’ll divide into pairs and turn over as many boards as we locate. Each time a board is
flipped, we will keep track of:
-
The species found under the board, and their abundance. Be sure to record the
number of boards in which no snakes were found, and mark an X on boards that
have been looked under using chalk.
-
How they escape the perceived threat of predation
Snakes may try to escape as soon as the board is lifted. If so, make note of the ways the snakes
move away. If the snake is staying motionless, record this and try to catch it. Again, as the snake
tries to escape this new predation threat, record its behavior.
FOLLOW UP QUESTIONS
Once back in the lab, we will compile data across the whole group by species, and see whether
the predictions you made before the field observations were correct. Follow up questions are
useful at this stage to draw from the field experience and enrich the learning environment. As a
group, we will develop different types of follow-up questions that are likely to further develop
students’ scientific inquiry, including questions that require quantitative evaluations of the data
collected.