National Lakeshore Michigan
One of the first questions people always ask when we talk about deer is, "How many deer do you really have?" We can't tell them exactly, but a pellet group survey is a research technique that can be demonstrated to show how deer numbers are estimated. With modifications and standardized procedures, you could actually use this survey technique in a research study.
For our purposes here, it is simplified for use as a good hands-on interpretive tool. This activity, which can be done easily with high school students or adults, is based on a National Park Service activity.
- 5-foot broom handle with an eye hook in the end and a 100-foot string attached
- survey info sheet (make them yourself) and pencils
Take your group to the area to be surveyed. Using the broom handle, mark off a plot 100 feet long and 10 feet wide. (You can use a smaller area if you want; be sure you know the length and width of your transect for the formula below.) Stretch the string out for 100 feet at right angles to the broom handle and tie off the loose end to a tree or stake. Lay the broom handle on the ground at right angles to the string.
Survey the side of the string on which the broom handle is located by walking down the length of the string and counting pellets groups. Survey out from the string a distance of 5 feet (the width of the broom handle). Keeping the string extended, flip the broom handle to the other side of the string. Walk back toward the broom handle, now surveying the opposite side of the string for pellet groups. If you were conducting an actual study, you would remove the pellet groups as you counted them.
You will have surveyed a 1,000 square foot area (10 feet by 100 feet).
Record pellet groups you find and use the formula on the next page to calculate the density of deer in the area you surveyed. Based on the size of your plot, you can extrapolate this to estimate the number of deer per square mile, hectare, etc.
Try this survey in several different habitats if you have time.
A = Transect length x transect width
N = Total number of pellet groups
I = Sampling interval in days (assume 30 days)
D = Daily defecation rate (=13)
P = Population density
P = A x N
D x I
"Seed" the area where you plan to demonstrate this activity with chocolate covered raisins. Scoop up a few and pop them in your mouth. Tell the students that the pellets taste fairly fresh …