Survival and harvest of ruffed grouse in central Maine, USA

Abstract

Understanding population dynamics is central to population management, particularly for game species that experience human harvest and non‐harvest mortality. Ruffed grouse (Bonasa umbellus) are a widely distributed and common game species in North America that have experienced population declines along their southern range margins, including portions of New England, primarily in response to forest succession and habitat loss. In the state of Maine, ruffed grouse are generally considered abundant, but there is a lack of state‐specific knowledge of ruffed grouse survival and harvest rates to inform harvest management. We estimated seasonal and annual survival rates, harvest rates, and documented cause‐specific mortality of 248 radio‐marked ruffed grouse at 2 study areas in central Maine from 2014 to 2016. We used Program MARK to evaluate sources of spatial, temporal, and individual variation that may affect ruffed grouse survival and harvest. Survival was lowest during October and during winter, and adult ruffed grouse had a higher survival probability than juveniles throughout the year with mean annual survival probabilities of 0.28 ± 0.01 (SE) and 0.13 ± 0.003, respectively. Harvest rates were greater in a state‐owned Wildlife Management Area and were lower within commercially managed private forest that was open to public hunting. Harvest results suggest harvest (H) was greatest at the beginning of the hunting season (Oct; Frye Mountain HOct = 0.14 ± 0.02; Stud Mill HOct = 0.07 ± 0.02), and was lower later in the season (Nov and Dec; Frye Mountain HNov‐Dec = 0.07 ± 0.02; Stud Mill HNov‐Dec = 0.03 ± 0.01). Pooled across all years and study areas, the ruffed grouse harvest rate was 0.16 (95% CI = 0.14–0.18). Our results are comparable to other range‐wide studies and suggest that current hunting regulations for ruffed grouse in Maine are consistent with sustainable population management. © 2018 The Wildlife Society.

Effects of forest characteristics on ruffed grouse nesting ecology in central Maine, USA

“…Other forest grouse species have been found to experience greater female mortality during nesting; a study of spruce grouse Falcipennis canadensis productivity in Maine observed mortalities for 26% of their sample of radio-marked females (Whitcomb et al 1996). When we compare the survival of nesting females during our study to spring survival of the population as a whole (Davis et al 2018), the mortality of females on nests (28.4%) was considerably higher than the background mortality occurring in the population at the same time (~10%), and was unlikely to have occurred based on chance alone. This indicates that nesting was a particularly risky activity for ruffed grouse females in our system, likely because of increased vulnerability to predators while associated with a nest.…”

“…Female ruffed grouse neither selected nor avoided areas for nesting that contained CWD, yet its presence in the immediate vicinity of the nest reduced overall nest success via its negative effect on female survival. We recognize that CWD is an important habitat component for breeding males, because males most often use fallen logs as platforms for their drumming displays (Zimmerman and Gutiérrez 2008, Davis 2017). However, Roy et al (2015) observed relatively broad distribution and high densities of drumming males in a system where limited CWD was present, which suggests that drumming platforms are not likely to limit components of ruffed grouse habitat.…”

“…Common mammalian predators included red fox Vulpes vulpes , striped skunk Mephitis mephitis , raccoon Procyon lotor , coyote Canis latrans , American marten Martes americana and fisher Pekania pennanti . Additional details about each study area may be found in Mangelinckx et al (2018), and see Davis et al (2018) for a description of ruffed grouse hunting within each study area.…”

“…Common tree species at SM included balsam fir, maple, spruce Picea spp., birch, eastern white pine Pinus strobus, northern white cedar Thuja occidentalis and big-toothed aspen Populus grandidentata. Additional details about each study area may be found in Mangelinckx et al (2018), and see Davis et al (2018) for a description of ruffed grouse hunting within each study area.…”

Detecting capture-related mortality in radio-marked birds following release

“…However, 95% confidence intervals of the coefficient overlapped 0.0 (β = -0.36; 95% CI = -0.90 to 0.17) and so support for the age effect was not equivocal. We nevertheless elected to retain the age effect, along with the year effect, in the second stage of analysis, because independent analysis of our larger telemetry dataset for this system demonstrate clear differences in survival among age classes (Davis 2017). …”