In our second model set considering habitat features, we found weak support for models of survival with land cover metrics. All top-ranked models were within 2 AICc of the intercept-only model and the top-ranked model had only 21% of the cumulative model weight (Table 2). We found a modest negative effect of Open habitat on survival, where confidence intervals overlapped zero slightly (β= -1.43, SE 0.81). We also found a modest effect of higher survival in Mature Forest cover, where the confidence interval overlapped zero slightly (β = 1.44, SE 0.75). Parameters for proportional cover of Dense Cover contiguity, and Dense Cover edge density were also present in top-models, but 95% confidence intervals overlapped zero. Models which included an effect for proportion of habitat with Dense Cover were not well-supported (Table S3).
Table 2. Model selection results for the effects of land cover on ruffed grouse overwinter survival. All models were within 2ΔAICc values of the intercept model. Variables below include % Mature Forest and % Dense Cover (proportions of mature forest or dense cover classes), Dense Cover Contig. (dense cover contiguity index), and Dense Cover Edge (edge density of dense cover). All values were averaged spatially over individual winter use areas and time-varying values were averaged temporally by week. Models ranked by AICc (Akaike’s Information Criterion, corrected for small sample size). ΔAICc represents the difference between the top-ranked model in the candidate set, w is the model weight, and k is the number of parameters. Only models within 2 ΔAICc of the top-ranked model and the intercept-only model are shown.