Date of Award

8-2017

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Erik Blomberg

Second Committee Member

Shawn Fraver

Third Committee Member

Amber Roth

Abstract

Species-habitat relationships are often complex, therefore effective management for forest wildlife requires a broad understanding of how forest structure and composition influence habitat use and vital rates during all aspects of annual life-cycles. The ruffed grouse (Bonasa umbellus) is a popular game bird that has long been a focal species for forest management, however, greater information on the links between forest characteristics and components of ruffed grouse reproduction would further enhance the ability of managers to promote the species. We monitored 45 ruffed grouse nests during 2015–2017 at two study areas in central Maine, USA, and evaluated the influence of forest characteristics on nest-site selection, nest survival, and female survival while nesting. Ruffed grouse females selected nest sites with greater horizontal visual obstruction (β = 0.163 ± 0.059 85% CI) and greater conifer stem density (β = 0.075 ± 0.054 85% CI) than found at other sites that were locally available to them, however, neither of these characteristics appeared to improve nest survival. Nest survival was reduced by the presence of coarse woody debris (CWD) at nest sites (β = -0.410 ± 0.332 85% CI), but we found no evidence that other habitat characteristics or characteristics of nests themselves were related to nest survival. However, reduced female survival while nesting was associated with the presence of CWD (β = -1.057 ± 0.778 85% CI), greater basal area (β = -0.632 ± 0.472 85% CI), and greater conifer stem density (β = -0.333 ± 0.224 85% CI) at nest sites. We provided management goals to promote attractive ruffed grouse nesting habitat while potentially mitigating multiple sources of nesting failure.

We also investigated multi-level resource selection and summer survival of non-reproductive and brood-rearing ruffed grouse in central Maine, USA, to understand the relationship between life-stage-specific resource selection and the cost of brood-rearing to ruffed grouse. At the landscape-level, non-reproductive ruffed grouse selected areas with greater stem densities (β = 0.26, 85% CI = 0.04 ˗ 0.48), while brood-rearing females avoided these areas (β = -0.38, 85% CI = -0.65 ˗ -0.12). Non-reproductive individuals further selected areas with greater stem densities at the local-level (β = 0.38, 85% CI = 0.04 ˗ 0.72), while brood-rearing females again avoided areas with greater stem densities (β = -0.66, 85% CI = -1.12 ˗ -0.21) and selected locally-available areas with greater ground cover by Rubus at this scale (β = 0.38, 85% CI = 0.13 ˗ 0.63). Weekly survival rates were reduced for brood-rearing females (S = 0.9487 ± 0.0250 SE) compared with non-reproductive individuals (S=0.9973 ± 0.0027 SE), which resulted in a 73% chance that a female would survive raising a brood to 6 weeks. In contrast, non-reproductive individuals had a 98% chance of survival over the same 6-week period. Our results suggest that non-reproductive ruffed grouse selected resources that reduced their mortality risk, thereby investing in survival and their future reproduction, while brood-rearing females selected resources to benefit current reproduction and also incurred a cost to their own survival.

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