Module 1: Endangered species population size

I ran my first module of the year with the Environmental Science students today. They were starting a new section on endangered species. This module served to introduce them to some general aspects and terminology of endangered species, and give them hands-on experience in some of the methods used to estimate population sizes.

Objectives:

• Introduce students to the topic of endangered species: basic terminology and issues.
• Encourage students to think about algorithms and demonstrate how they can be used to solve problems; how Excel can be used to enter, manage, and analyze data.
• Experiment with three methods for estimating population size.

 [link to module summary] [link to module slides]

Module details:

I set up the module so that students would be able to experiment with three ways scientists use to estimate population sizes, which is crucial to determining whether a species is endangered, and in monitoring endangered populations. Students formed 6 groups of 3-4 students. Each group was provided with a "habitat" (a plastic bin) and many "individuals" (grains of rice). Because we used white rice to simulate individuals, each group picked a predominately white species for which they would estimate population size. Students picked the Great White Shark, Polar Bear, Snowy Owl, Mexican Grey Wolf (grey was deemed "close enough" to white), Showshoe Hare, and White Tiger (yes, we discussed that this is a mutation and not a species, but it was allowed to slide!).

Students released their individuals into the "wild" while being careful to prevent "escapes".

Experiment 1: Quantify population size by finding and counting all individuals

Experiment 2: Estimate population size by counting all individuals in a small area and then extrapolating to the total area of habitat.

Experiment 3: Estimate population size by running a mark-recapture experiment.

One major problem that quickly emerged is that the rice grains were a bit too small and much too numerous. Students became overwhelmed by the sheer amount of individuals to count (especially in Experiment 1) and the counting was pretty lengthy and tedious. This would have worked much better with something a little bigger -- white beans would probably work well. The rice grains were also difficult to mark for Experiment 3 because of their small size; again, something larger like a bean would have worked much better.