Survival of Reintroduced Ruffed Grouse in North Missouri

Abstract

We studied survival of a reintroduced ruffed grouse (Bonasa umbellus) population in north Missouri from 16 September 1986 to 30 April 1987. Estimates of survival were derived from 77 radio-marked grouse with the Kaplan-Meier product-limit method. Survival from release to spring was 0.245 ? 0.05 (SE) and was not constant. Most losses occurred from release through fall. Adult male survival differed from that of immature males and immature females. No other differences were evident among age and sex classes. Grouse whose movements exceeded the mean daily movement had higher mortality rates than more sedentary birds. Survival of grouse into the breeding season may limit the success of reintroductions. J. WILDL. MANAGE. 52(2):248-252 Ruffed grouse were extirpated from major portions of their southern range during the late 1800's and early 1900's because of exploitative land use practices (Bump et al. 1947, Lewis 1970). Unregulated sport and market hunting also contributed to the decline (Hunyadi 1984). Since the 1950's many states have initiated ruffed grouse restoration programs with varied success (Lewis et al. 1968, White and Dimmick 1978, Backs 1984, Woolf et al. 1984). Estimates of grouse survival from release until the subsequent breeding season are useful to evaluate restoration programs. However, data are not available concerning the effect of condition or movements on the survival of reintroduced ruffed grouse. Objectives of our study were to determine survival of reintroduced ruffed grouse in north Missouri during September 1986-April 1987 and to examine the effect of condition and movement on grouse survival. We thank J. A. Balkenbush and V. L. Kimmel-Truitt for assisting in field work. The staff of the Missouri Department of Conservation, Kirksville, provided essential assistance. G. S. Olson and S. L. Sheriff assisted with data analyses and study design. This study was supported, in part, with the Federal Aid in Wildlife Restoration Act funds, under Pittman-Robertson Project W-13-R. R. M. Scheidt typed drafts of the manuscript. L. D. Vangilder, E. K. Fritzell, J. B. Lewis, D. T. Zekor, and F. R. Thompson reviewed the manuscript. STUDY AREA AND METHODS From 16 September to 7 October 1986, 77 ruffed grouse (42 ad, 35 immature) were released on Sugar Creek State Forest (SCSF) in Adair County, Missouri. Wild-trapped grouse were obtained from the Indiana Department of Natural Resources through a cooperative agreement with the Missouri Department of Conservation. The 1,056-ha SCSF, located in northcentral Missouri, is >90% forested. Most stands are composed of small sawlog and pole-sized oak (Quercus spp.) and hickory (Carya spp.). Since 1980, 7 stands totaling 72 ha were clearcut on SCSF and 128 ha received intermediate thinnings. Private lands surrounding the study area are a mosaic of forest, pasture, and cropland. Vegetative conditions of SCSF met the criteria for ruffed grouse release sites in Missouri (Hunyadi 1984, Kurzejeski et al. 1987a): a minimum size of 404 ha, predominantly forested, >10% in early forest succession, and an active timber management program. Grouse were released in a 6-year-old clearcut (9.8 ha) centrally located within the eastern unit of SCSF. Age (Davis 1969), sex (Roussel and Ouellet 1975), and weight of grouse were determined at release. Weight loss between time of capture and release was recorded and used as an indication of condition. Each bird was fitted with a mortality-sensitive, poncho-mounted transmitter (Advanced Telem. Systems, Inc., Isanti, Minn.). The 16-18-g transmitters had an expected life of 200 days and were assumed not to affect movements or survival of grouse (Small and Rusch 1985). We attempted to relocate grouse daily from date of release through 30 April 1987 with vehicle-mounted antennae and portable receivers. When necessary, fixed-wing aircraft were used to relocate grouse. Triangulation error with the vehicle-mounted antenna system was estimated at ?1.440 (n = 448) (Springer 1979). We estimated time of death within 24 hours of receiv-