Date of Award
Doctor of Philosophy
Craig A. Harper
David A. Buehler, Frank T. van Manen, Arnold M. Saxton
Ruffed grouse populations are lower in the Appalachians compared to the Great Lakes states, the geographic core of grouse distribution. Theories to explain lower numbers in the Appalachians include inadequate foods, lower reproduction, lower survival, and loss of habitat. To provide insight into ruffed grouse ecology in the Appalachians, habitat use, reproduction, and survival were studied on Nantahala National Forest in western North Carolina. Radiotagged grouse (n = 276) were monitored through the year. Seasonal 75% kernel home ranges (n = 172) averaged 15–59 ha across sexes, ages, and seasons. Home range size was related to habitat with smaller ranges occurring where 6–20-year-old mixed oak (SUBXER2) and forest roads (ROAD) were interspersed with other habitats. Across seasons, sexes and ages, SUBXER2 and ROAD were among preferred habitats. Compared to males, females used greater diversity of habitats, including >40-year-old stands. Use of older stands may have been influenced by food availability (i.e., hard mast). Nests (n = 44) were located to determine fate. The majority of nests (86%) were on mid and upper slopes in mature stands >40-years old. Proportion of successful nests was 81%. Mayfield nest survival was 0.83 (+ 0.084 SE) and did not differ between juveniles and adults. Nesting rate was 73% and did not differ between juveniles and adults. One female renested, though high nest success precluded opportunities for documenting extent of renesting. Mean first nest clutch was 10.1 eggs. Broods (n = 35) were monitored intensively following hatch. Brood sites had greater herbaceous ground cover, vertical cover, midstory stem density, and invertebrate density compared to random sites. Mean home range size was 24.3 ha (+4.0 SE ) using 75% kernel methods and 40.0 ha (+ 4.0 SE) using MCP. Preferred habitats were mixed oak
0–5, 6–20, and >80-years old, forest roads, and edges of maintained clearings. Mean annual survival of grouse >3 months old was 0.39 (+ 0.052 SE). Of mortalities, 43% were from mammalian predators, 27% avian, 13% unknown predation, 11% hunter harvest and 7% other causes. Scavenging prior to transmitter recovery may have inflated mammalian predation rates. Relatively low hunter harvest did not appear to be additive to natural mortality. Spring population density, estimated from drumming counts, decreased from 11.4 grouse/100ha in 2000 to 5.88 grouse/100 ha in 2004. Fall population density indexed by catch per unit effort also decreased during the study from 0.96 grouse/100 trap-days in 1999 to 0.19 grouse/100 trap-days in 2003. The fall population index was inversely related to annual survival (r2 = 0.76, P = 0.054). The inverse relationship may have been a function of habitat availability. Annual recruitment indexed by proportion of juveniles in fall captures was less than reports from the northern core of ruffed grouse range. Overall percentage of juveniles in fall captures was 59.6%, ranging from 46.2–66.7%.
Recommendations to increase grouse density include creating a diversity of forest types and age classes interspersed across the landscape. Alternative regeneration techniques such as shelterwood, irregular shelterwood, and group selection can be used to intersperse food and cover, thus improving grouse habitat.
Jones, Benjamin Colter, "Ruffed Grouse Habitat Use, Reproductive Ecology, and Survival in Western North Carolina. " PhD diss., University of Tennessee, 2005.