Activity 6C Analysis
Analysis of Fall Mule Deer Census Data Work Sheet
1. Number of deer per census
The average number of deer seen per census is the yearly index to population trend. Calculate the mean for the total number of deer in each sex and age class for the six samples collected in the fall of this year. (Add the number of deer seen in the six samples for each age class and divide by six to get the mean.)
2. Sex and age ratios
Combine the data from the six censuses and calculate the ratio of adult males, yearling, males and fawns per 100 females. To accomplish this, divide the total number in each age class by the number of females and multiply by 100. For example, consider a series of six censuses which yielded a total of 75 deer that included 10 adult males, 4 yearling males, 25 females, and 31 fawns. The classification would be calculated as follows:
10 adult males x 100 = 40 adult males
25 females to4 yearling males x 100 = 16 yearling males
25 females to25 females x 100 = 100 females
25 females to31 fawns x 100 = 124 fawns 25 females
Disregard deer of unknown sex and age classes when making these calculations.
3. Estimating the Number of Deer in the Craters Herd
During research conducted in 1980-82, biologists estimated the size of the deer herd both through the census procedure still in use, and by marking and recapturing deer. The relationship between the average daily standard census totals and mark-recapture population estimates was quantified and enables us to continue to estimate the size of the deer population based on our census figures.
Where y = mark-recapture population estimate and x = average daily standard census total, the regression equation relating y and x is y = 7.295x + 19.056. To estimate the late summer total deer population, (y), substitute the average daily standard census total for x in this equation and solve for y. For example, if the average daily standard census total (x) is 50. Then
y = (7.295)(50) + 19.056 = 384 deer
4. The 95 percent confidence interval on this estimate is given by the following equation, where y = late summer deer population (from calculation in #3) and x = average daily census total (from calculation in #1).
which is equivalent to 384 +/- 106.0. In other words, there is a 95 percent confidence that the total number of deer lies between 278 and 490.
| Sex and Age Class | Census 1 | Census 2 | Census 3 | Census 4 | Census 5 | Census 6 |
|---|---|---|---|---|---|---|
| Adult Males | 5 | 0 | 0 | 3 | 2 | 4 |
| Yearling Males | 1 | 3 | 0 | 3 | 0 | 2 |
| Females | 25 | 24 | 17 | 15 | 25 | 14 |
| Fawns | 24 | 14 | 10 | 13 | 19 | 7 |
| Unknown | 0 | 0 | 0 | 0 | 0 | 0 |
| TOTAL | 55 | 41 | 27 | 34 | 46 | 27 |
Summary Of Standard Deer Censuses 1993
| Sex and Age Class | Census 1 | Census 2 | Census 3 | Census 4 | Census 5 | Census 6 |
|---|---|---|---|---|---|---|
| Adult Males | 0 | 1 | 0 | 0 | 0 | 0 |
| Yearling Males | 0 | 0 | 0 | 0 | 0 | 0 |
| Females | 11 | 8 | 2 | 0 | 7 | 6 |
| Fawns | 6 | 9 | 2 | 0 | 7 | 4 |
| Unknown | 0 | 0 | 0 | 0 | 0 | 0 |
| TOTAL | 17 | 18 | 4 | 0 | 14 | 10 |
Results of the Fall Mule Deer Census Calculations
| 1992 | 1993 | |
|---|---|---|
| Mean # of Deer for the Six Fall Censuses | ||
| Adult Males Yearling Males Females Fawns Total Sample |
2.3 1.5 20.0 14.5 38.33 |
0.17 0.0 5.7 4.7 10.5 |
| Sex and Age Ratios: | ||
| Adult Males Yearling Males Females Fawns |
11.7 7.5 100.0 72.5 |
2.9 0.0 100.0 82.4 |
| Late Summer Total Deer Herd Estimate | 299 | 96 |
| 95% Confidence Interval on Mule Deer Population Size | 299 +/- 141 | 96 +/- 261 |