Table 1. Results of the nonparametric Mann-Whitney U-tests comparing pre- and post-harvest distributions of the percentage of nesting habitat left undisturbed by timber harvesting within a 1-km radius of indicated breeding pair (IBP) locations. Tests include all IBP located within 2 km of clear-cut areas. Median percentages of undisturbed nesting habitat and pre/post median differences are presented: a negative difference indicates a lower undisturbed nesting habitat (higher % of clear-cut) after treatment than before, and vice-versa. Statistics are given for all individual species totaling over 30 IBP, for guilds of ground nesters and cavity nesters, and for all species combined.

Period IBP numbers Median % of undisturbed nesting habitat Pre/post
difference
(%)
Z P
Ground nesters
Canada Goose Pre- 37 97.3 -13.0 -2.224 0.026
Post- 94 84.3
American Black Duck Pre- 241 89.0 -0.4 -0.962 0.336
Post- 344 88.6
Mallard Pre- 12 92.4 1.0 0.817 0.414
Post- 39 93.4
Green-winged Teal Pre- 42 92.9 -10.4 -2.254 0.024
Post- 65 82.5
Ring-necked Duck Pre- 149 93.1 -2.3 -1.092 0.275
Post- 154 90.7
Common Loon Pre- 56 91.8 2.1 0.809 0.419
Post- 71 93.9
Total Pre- 563 91.7 -2.0 -2.152 0.031
Post- 778 89.6
Cavity nesters
Common Goldeneye Pre- 144 85.9 -4.2 -0.907 0.365
Post- 162 81.8
Common Merganser Pre- 148 89.9 1.0 -0.428 0.669
Post- 152 90.9
Hooded Merganser Pre- 24 98.7 -0.6 0.053 0.958
Post- 50 98.2
Total Pre- 337 89.6 0.3 -0.165 0.869
Post- 380 89.9
All species total Pre- 901 91.3 -1.6 -1.618 0.106
Post- 1,160 89.7
: Z approximation of Mann-Whitney U test statistic.