PURPOSE:  To estimate the number of deer in a given area using an index method.

MATERIALS: Suitable winter clothes, snowshoes or cross-country skis, map and compass, shovel, flagging tape or brightly-colored strips of cloth, index cards, pencil, meter stick. Optional: Field guides to mammals and tracks.

INTRODUCTION:  Wildlife biologists often need to know how many animals there are in a given area.  They could actually count them, but this isn't always practical or even possible.  Indirect methods using mathematical relationships to estimate the population size are easier and often nearly as reliable as direct counts.  One such technique is the McCain Index method, used for members of the deer family (deer, moose, elk, and caribou).  It relies on the knowledge that deer defecate in piles about 13 times per day.  In this activity, you will count "poop piles" - or scats as scientists prefer to call them - to estimate the size of a deer population using the McCain Index method.

INITIAL FIELD PROCEDURE: Work with a partner. Be sure to use a map and compass in rural or wilderness areas. 

A.  Select an area that you suspect is inhabited by deer. Look for deer signs such as tracks, browsing, bed sites, and scats.

B.  Use the flagging tape or cloth strips (or other method of your choice) to mark off the boundaries of your study site.  Rectangular study sites of 30-100 m per side are adequate.

C.  Sketch a simple map of your site on an index card, including the type of vegetation and physical features like hills and ponds.  Record approximate distances along boundaries.  Distances should be estimated by recording the number of strides along boundaries, and then measuring average stride length in meters.

D.  Remove or cover with snow all fresh scat piles found in your study site, and wait 24 hr. Calculate the area of your study site.

PREDICTION: Use your initial observations of deer signs in your study area to make a prediction. 

1.  How many deer (one, few, many) do you think regularly use your study site?

DATA COLLECTION PROCEDURE: You may wish to collect data for several days to get more reliable information.

E.  Return to your study site 24 hours later.  On an index card, record the number of fresh scat piles.  Cover them with snow as you count them to avoid duplication. 

F. Estimate and record the average snow depth (cm) in your study site.

G.  As you collect the scat and snow data, try to determine how the deer are using the habitat.  On an index card, record the availability of food, water, and shelter in your study area.

H.  Calculate the estimated number of deer that use your study area, using a McCain Index value of 13 scat piles/deer/day.  For example, 40 scat piles are the equivalent of about 3.1 deer.

I. Calculate the estimated deer population size per hectare based on your data. Share your data with the class.

YOUR DATA:

               Area of Study Site:          m2 
                                   ------------ = __________ha
                                   10,000 m2/ha

| Average:_______________________________

CLASS DATA:

CONCLUSIONS:

2. How did your prediction compare to the actual population estimate?

DISCUSSION:

3. How did the deer in your study area seem to use the habitat?

4. Using class data, what habitats do deer seem to prefer?  Give possible reasons for your findings.

5. Describe another method for determining deer populations.

6. What other animal populations can you estimate without actually counting individuals?  Explain your ideas.

7. If you were to perform this study again, how would you improve it?