490 
Table 1. Comparison of new gopher mound counts obtained by photointerpretation 
of 1:600 scale color infrared aerial photos with actual ground counts 
of new pocket gopher mounds. 
Item 
Interpretation Results 
PI-1 
PI-2 
PI-3 
Mean 
Ground Count (No.) 
226 
226 
226 
226 
Photo Count (No.) 
148 
130 
102 
129 
Omission Error (No.) 
121 
129 
152 
134 
Omission Error (%) 
53.5 
57.1 
67.2 
59.3 
Commission Error (No.) 
43 
41 
28 
37 
Commission Error (%) 
19 
18.1 
12.4 
16.5 
Total Error (No.) 
164 
170 
180 
171 
Correct PI (No.) 
105 
97 
74 
92 
Correct PI (%) 
46.5 
42.9 
32.7 
40.7 
Table 2. Comparison of pocket gopher population estimates by ground mound 
counts and photointerpreted mound counts using 1:600 scale color 
infrared photography by three photointerpreters. 
Plot 
Ground population 
estimate 
Photointerpreted Population Estimate 1 
PI-1 
PI-2 
PI-3 
A 
41 
38 
40 
36 
B 
34 
44 
36 
40 
C 
28 
25 
30 
35 
D 
22 
35 
37 
28 
E 
40 
26 
29 
32 
F 
40 
31 
26 
25 
Mean 
34 
33 
33 
33 
^-Adjusted for the difference between ground mound counts and photointerpreted 
mound counts on a plot-by-plot basis.