Small Mammal Communities at BFREE A field exercise for student groups

While visiting the BFREE field station in southern Belize, you have the opportunity to study the small mammal communities living in the cacao plantation and the nearby forest. You will learn about trapping methods, how to handle and identify the small mammals, and some basic data analyses. Continue reading below to familiarize yourself with this study.

Left: Forest spiny pocket mouse. Right: Student attaching ear tag to small mammal

Justification for the study. Expansion of agriculture to support growing human populations catalyzes loss of biodiversity in Mesoamerica. Many scientists have hypothesized that more structurally diverse agriculture systems such as shaded and rustic cacao agroforests will support higher levels of biodiversity than more intensively managed plots. BFREE's property makes an ideal location for students to examine the biodiversity supported by a rustic cacao farm and compare it to the surrounding forest.

In 2006, BFREE planted an experimental organic shade cacao agroforest to serve as a example of sustainable agroforestry to regional farmers.
Chocolate products made from cacao harvested at BFREE

Why sample small mammals? Previous studies in the Bladen Nature Reserve have shown that small mammals, especially the forest spiny pocket mice, are important seed dispersers and seed predators. Additionally, vertical stratification is an important habitat component for small mammals. Consequently, small mammals may be especially sensitive to differences in habitat structure between cacao farms and forest habitats.

Clockwise from upper left: Student holding Mexican mouse opossum; Forest spiny pocket mouse; Mexican mouse opossum (last photo by Dan Dourson)

Study Methods. In January 2015, permanent small mammal trapping grids were established in the cacao farm and in the nearby forest. In June 2016, an additional grid was established in edge habitat between the cacao and forest habitats. In each grid, 10 rows of 10 numbered flags are anchored to the ground. Flags are set 7 meters apart. During your participation in this study, you will set a small Sherman trap near each numbered flag.

Left: Small mammal trapping grid in BFREE cacao farm. Note the pink flags on the ground starting in the foreground and running back. Right: A single Sherman trap is set at each numbered flag in the grid.

To attract species with different diets, a combination of peanut butter, oats, and fruit jam is used as bait. See the videos below which show how to prepare the bait and how the traps work.

From Left: Student holding small mammal in ziplock bag; Big-eared climbing rat.

Trapped animals should be transferred to a ziplock bag to identify the species, and to document weight and sex of the animal. An ear tag should be attached to each animal and released at trap location. See the videos below for demonstrations.

Ear tag shown from back of ear on forest spiny pocket mouse.

Once you collect your data using the data sheets provided by BFREE, you can work with your instructor to complete some basic data analyses and to compare your results with previous trapping cycles.

More detailed background about this exercise and instructions for both instructors and students can be found at BFREE's website.

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