Gutiérrez, R.J., Zimmerman, G.S. & Gullion, G.W.† 2003: Daily survival rates of ruffed grouse Bonasa umbellus in northern Minnesota. - Wildl. Biol. 9: 351-356.
We radio-marked 56 ruffed grouse Bonasa umbellus in northern Minnesota, USA, during 1963-1965 and 2001-2002. Of these, we estimated the daily survival rate of 49 individuals (32 females and 17 males; of which 27 were grey phase and 22 were red phase) during the breeding and non-breeding seasons. We investigated whether daily survival varied by age, colour phase, gender, season and transmitter type. A model representing an interaction between colour phase and season fit the data best (AICc = 154.760) and was 77% more likely than any of our other a priori models. Daily survival rates were identical during the breeding season (0.998; SE = 0.002 for both colour phases), but higher for red-phased (0.994; SE = 0.003) than for grey-phased (0.980; SE = 0.007) birds during the non-breeding season. The daily estimate of grouse survival pooled across all individuals and seasons was 0.994 (SE = 0.002), which yielded an annual survival probability of 0.111 (SE = 0.082). The estimated annual survival rate was 0.010 (SE = 0.132) for grey-phased birds and 0.206 (SE = 0.146) for red-phased birds. There was no difference in survival rates between the two study periods. Our estimated annual survival rates were similar to other rates reported for ruffed grouse.
Key words: Bonasa umbellus, Galliformes, known-fate modelling, radio telemetry, ruffed grouse, survival rate
R.J. Gutiérrez, Guthrie S. Zimmerman & Gordon W. Gullion†, Department of Fisheries, Wildlife & Conservation Biology, University of Minnesota, St. Paul, MN 55108, USA, and the Cloquet Forestry Center, University of Minnesota, Duluth, MN 55720, USA - e-mail addresses: gutie012@tc.umn.edu (R.J.Gutiérrez); zimm0242@umn.edu (G.S. Zimmerman)
† Deceased
Corresponding author: R.J. Gutiérrez