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Research: Small Mammals Survey

Dates Conducted: 1988 - present
Lead Researcher: Dr. Randy Van Dragt, Professor of Biology & Director of Ecosystem Preserve
Student Researchers: Summer Preserve Stewards/Researchers


Small mammals are an important part of the food web in any ecosystem, as they provide sustenance for larger animals. Conducting a survey on the small mammals inhabiting the preserve allows researchers to understand how many species there are here, as well as their relative numbers, and any population trends in the species. This also provides an indication of which larger animal species are likely present, based on the available food sources.

The Study

Every year, both the Paul and Carolyn Buiten Wildlife Sanctuary and the public area of the preserve are monitored for small mammals. Sherman traps are set up in a grid pattern, with 20 meters of space between each one. Each study area takes 4-8 nights to complete; two lines of 10-15 traps each are placed and left out each night. The weather plays an important role in determining when the traps are set. In order to keep the mammals safe, traps are only set if the overnight forecast is temperate enough (40°F or warmer), and dry enough (less than 30% chance of rain). Traps are baited, and furnished with one gram of cotton for nesting. In the morning, a record is taken of whether or not the trap has sprung, and if there is anything inside the trap. If an animal is caught, Preserve Stewards place a Ziploc bag over the trap door, allowing the animal out for easy identification and measurement. Also documented are its weight in grams (using a spring scale), hind foot length in millimeters, and gender. The animal is marked with a dye (to allow for identification of a recaptured animal), and released. Data collected is then extrapolated using a Lincoln index, to estimate small mammal populations for the preserve as a whole.

Measuring the hind foot length of a mouse

Weighing a mouse

Small Mammals Found in Study Area

Meadow voles
(Microtus pennsylvanicus)

White-footed mice
(Peromyscus leucopus)

Deer mice
(Peromyscus maniculatus)

Masked shrews
(Sorex cinereus)

Eastern chipmunks
(Tamias striatus)

Meadow jumping mice
(Zapus hudsonius)

A Sherman trap set for the evening

Meadow jumping mouse

White-footed mouse