Geoscience Reference
In-Depth Information
Table 7.2
Variability Estimates for Local Populations
Group
N
CV
Mammals, large
17
0.142
Grasses and sedges
16
0.209
Herbs, Compositae
9
0.213
Herbs, non-Compositae
32
0.225
Turtles
7
0.333
Terrestrial salamanders
8
0.354
Large-bodied birds
25
0.363
Lizards
11
0.420
Fishes, salmonids
42
0.473
Caddis flies
15
0.497
Snakes
9
0.541
Dragonflies
8
0.566
Small-bodied birds
73
0.569
Beetles
20
0.580
Small mammals
14
0.597
Spiders
10
0.643
Medium-sized mammals
22
0.647
Fishes, nonsalmonids
30
0.709
Pond-breeding salamanders
10
0.859
Moths
63
0.903
Frogs and toads
21
0.932
Bats
24
0.932
Butterflies
13
1.106
Flies, drosophilids
13
1.314
CV = coefficient of variation,
N
= number of detrended count series of at least 5 years' dura-
tion obtained from the literature. Values are average coefficients of variation (standard devia-
tion/mean) for standardized 5-year count series. Data sources are listed in appendix 7.1.
SAMPLING REQUIREMENTS FOR ROBUST MONITORING PROGRAMS
Estimates of index variabilities (table 7.2) were incorporated into a power
analysis (table 7.1) to generate sampling recommendations for animal ecolo-
gists for designing effective programs for monitoring local populations. The
power analysis assumed the following logistical constraints. Resources avail-
able for a local or regional monitoring program would permit surveys of up to
500 plots or subpopulations on one to five occasions annually over a monitor-
ing period of 10 years. Average plot counts for all groups were assumed to
