TABLE A3.
Top N‐mixture model for ruffed grouse drumming surveys each year as determined by AICc selection including estimates of detection and abundance with 95% confidence intervals (CI), Michigan's Upper Peninsula, USA, 2013–2015
| Year | Model a | Detection estimate (%) | Abundance estimate b | 95% CI |
|---|---|---|---|---|
| 2013 | ~date ~ asp | 24.5 | 178 | 93–346 |
| 2014 | ~date ~ 1 | 15.8 | 151 | 79–1246 |
| 2015 | ~date ~ 1 | 33.4 | 137 | 92–239 |
a
N‐mixture model includes covariates of detection on the left and abundance on the right. The “date” covariate was Julian date. The null model (intercept only) is indicated as “1.” Covariates for ruffed grouse include “asp” as the proportion of aspen (Populus tremuloides or P. grandidentata) as land cover within each survey site.
b
Abundance estimates are for the audible area surveyed (550 m diameter with 65 sites for grouse) and only include estimates of abundance for drumming males in grouse surveys.