Fox Squirrel Population Estimate

Population biologists must have a method to estimate populations when it is impossible to account for each individual in the population. This exercise will have you and your group observing portions of a population at various sites in the study area. The population you will be estimating will be the Fox Squirrel population in McKennan Park in central Sioux Falls. This exercise will require you and your group to be at the park to make observations at each of the index areas two times during the fall season. Squirrels are most active during the early morning hours and late afternoon hours.

Procedure  The park will be divided into 21 sections. Each section will be assigned a density index. The index will include three possible categories: high density, medium density, and low density. Index category will be determined by the density of trees and the type of trees. High density areas will have large numbers of trees, including walnut trees. Medium density will have average to large numbers of trees but few walnut trees. Low density will have few to no trees. Using the high altitude photograph and a short visit to each section will determine whether there are walnut trees present. The combination of this information will allow the group to make decisions about whether the sections would be considered high, medium, or low density in nature. Assign each plot a density index number based on observations. 1 = low density, 2 = medium density, and 3 = high density.

 Observe a “typical” plot in each of the density index areas. 1. Locate the general area of the park with the corresponding density index. These areas will be marked on a high altitude image of the park. 2. Find the (50m x 50m) plot that has been laid out within the area boundaries. Corners will be marked with paint on the grass. Put your four flags in the corners of the observation area. 3. Leave the area for 5 minutes and then return to observe the plot for 30 minutes. All observations must be from outside the boundaries of the plot while sitting still. Choose a good vantage point and bring a chair. 4. The total number of squirrels observed in the plot during the 30 minute period, will be recorded. a. Every effort must be made to not count individual squirrels more than one time. b. Count squirrels in the trees as well as on the ground. c. The entire tree whose trunk is located in the plot is considered in the plot. Branches of trees with trunks outside of the plot are not considered in the plot. 5. REMOVE YOUR FLAGS WHEN YOU ARE FINISHED WITH YOUR OBSERVATIONS

After all class data has been compiled, we will work with the Fathom 2 program to make some computations.

 Enter the data in the lists on the graphing calculator as well as recording them in a notebook data table  Calculate the average squirrel density for each of the typical density plots.  Determine the density index of each of the 21 sample plots, based on numerical assignment by each group.  Apply the calculated squirrel density to the total area of each density type in the park to estimate the total number of Fox Squirrels in the park.

Determine confidence intervals  Using the graphing calculator determine the 95% confidence intervals for our population.

Produce a lab report for this lab using the formal lab report format