Small, R.J., Holzwart, J.C. & Rusch D.H. 1996: Natality of ruffed grouse Bonasa umbellus in central Wisconsin, USA. - Wildl. Biol. 2: 49-52.
Radio-marked female ruffed grouse Bonasa umbellus were monitored in central Wisconsin, USA, during 1983-1988 to estimate nesting rates (the percentage of hens that initiate a clutch), clutch size, nest success, and the prevalence and success of renests. All 23 radio-marked females initiated a clutch, 22 completed a first clutch; the remaining hen was killed by a predator during laying. Mean clutch size of first nests was 11.0 ± 0.5 eggs (range = 7-13). Five of nine (56%) hens attempted to renest with a mean clutch size of 7.4 ± 1.3 eggs (range = 6-9). Mean nest success was 46%; 43% for yearlings and 60% for adults. First nests produced the large majority of eggs that hatched (86.1%) compared to renests (13.9%). Productivity was estimated at 5.8 chicks hatched for each hen alive on 20 April, the mean date of the first egg laid.
Key words: clutch size, natality, nest success, renest, ruffed grouse, Bonasa umbellus, Wisconsin, USA
Robert J. Small & James C. Holzwart*, Department of Wildlife Ecology, University of Wisconsin, Madison, WI 53706, USA
Donald H. Rusch, National Biological Service, Wisconsin Cooperative Wildlife Research Unit, University of Wisconsin, Madison, WI 53706, USA
Present address: Wisconsin Department of Natural Resources, P.O. Box 343, Berlin, WI 54923, USA
Received 17 November 1995, accepted 27 February 1996
Associate Editor: Ralph J. Gutiérrez