Small mammals - mice, voles, chipmunks - are one of the most abundant but least visible groups of organisms in schoolyard habitats. Since trapping and handling these animals requires special care, their populations can best be studied in a school setting indirectly, i.e., by measuring their activity. One way to do this is to set out attractive baits - peanut butter, seeds, etc. - and then measure their disappearance rates over time. To try to identify what species are visiting the baits, they can be set in a surface that records their tracks.

In this study, you will use bait stations made from dark-painted aluminum flashing coated with white talcum powder. Ideally, animals that come to the bait will leave their footprints as dark marks in the white powder. By placing similar bait stations in different areas you can ask questions about habitat preference. Or, you can use different baits to assess food preferences.

• 4" x 6" pieces of dark-painted aluminum flashing
• mineral oil
• stakes and flagging to mark locations of bait stations
• permanent marker to number locations
• white (unscented) talcum powder
• field guides for identifying tracks of organisms
• paper towel for applying mineral oil
• measuring spoons (at least 1/8 and 1/4 tsp)
• baits (peanut butter, seeds, etc.)
• camera for recording results

1. Write down the population ecology question you want to address, along with your hypotheses.
   
2. After exploring the schoolyard, devise a scheme to address your question.
   
3. Select the site or sites you will need, trying to make sure conditions within the site(s) are as uniform as possible.
   
   

1. Put some mineral oil on a piece of paper towel.
   
2. Holding the edges, coat the top of each piece of flashing with a very thin layer of mineral oil.
   
3. Coat the entire surface of the flashing with a uniform layer of powder and carefully shake off excess.
   
4. Place a tiny but standard amount of bait (e.g., 1/8 tsp) in the very center of each piece of flashing.
   

1. Place each bait station so that it sits flat on the ground. Take extreme care not to disturb the bait and powder surface.
   
2. Each replicate bait station should be in as similar a setting as possible.
   
3. Mark the location of each station with a stake and flagging, number the station and record the number and treatment.
   

1. Examine each bait station. Quantify how much of the bait is missing.
   
2. Record your observations about the tracks at each bait station. Can you identify the animal(s) that visited? Can you quantify the number or amount of activity or tracks?
   
3. If possible, photograph each bait station to identify tracks at a later time, keeping careful records of which station is which.