Natal Dispersal and Lek Fidelity of Sage Grouse

摘要: -Natal dispersal and lek fidelity (attendance within between years) of Sage Grouse (Centrocercus urophasianus) were studied on Cold Spring Mountain, northwestern Colorado, from July 1981 through May 1984. Female followed the typical avian pattern dispersing farther than males. However, there was no difference proportions male female yearling grouse attending closest to their juvenile banding location. Fifteen percent all individually marked juveniles (24/157 birds) known have attended leks as yearlings. There adult attendance rates for either sex; however, females less often Yearling females, but not males, visited 2 or more adults. These differences may be related yearlings' inexperience with breeding a strategy enhance reproductive success. Received 9 1984, accepted 6 March 1985. DISPERSAL has major role in population regulation (Lidicker 1962, Krebs et al. 1976) distribution (Taylor Taylor 1977). It also evolution song dialects (Baker Mewaldt 1978), mating systems (Greenwood 1980), stability local populations (Reddingius den Boer 1970). Despite its potential importance, studies are few; most research investigated fall movements, movement natal initial areas. been even fewer species that show exceptions general greater dispersal. Greenwood (1980) proposed both femalebiased monogamy can consequence resource-defense system. Bird Greenwood's hypothesis because males do appear defend resources required by females. If is relationship among intensity direction sexual selection, systems, patterns (Oring Lank 1982), then an ideal which study they exhibit some greatest variation success Present address: Department Zoology, University Alberta, Edmonton, Alberta T6G 2E9, Canada. lekking (Payne 1984: 8). Here we describe years, movements leks) Colorado. We examined determine whether follow present data philopatry (birds 8-10 months old) relate recent hypotheses concerning systems. STUDY AREA AND METHODS The conducted Mountain (2,622 m) Moffat County, Colorado adjacent parts Wyoming Utah June 1983 3 days April area semiarid sagebrush (Artemisia spp.) rangeland interspersed quaking aspen (Populus tremuloides) pinyon pine (Pinus edulis)-Utah juniper (Juniperus osteosperma) stands, meadows. Lodgepole contorta) Douglas fir (Pseudotsuga menziesii) occur above 2,620 m Middle (2,904 Diamond Peak (2,909 near border. since 1978. From 120 300 banded during August each year. In 1982, captured numbered aluminum bands unique combinations colored plastic bands. Drive traps, bumper-mounted cannon net, 621 Auk 102: 621-627. 1985 This content downloaded 207.46.13.112 Mon, 03 Oct 2016 05:16:17 UTC All use subject http://about.jstor.org/terms 622 DUNN BRAUN [Auk, Vol. 102 spotlighting long-handled nets used capture (Giesen 1982). Captured birds classified sex age wing molt primary length (Beck 1975). Lek searches made at least 5 days/week late 1982 those springs previous summers. 1984 (22 April, 8 May) observe changes where displayed recorded observations calculated straight-line distances location bird observed displaying (attended) yearling. approximation juvenile's before long-distance (>2 km) took place (Wallestad 1971; unpubl. data). For one lek, frequently occurred calculating distances. number divided total depending particular bird, multiplied 100. Attendance corrected spring season (26 males) subtracting respective sex's prior bird's denominator. example, #9947 Gee Flats 11 after seen. Therefore, seen (37) minus (6) equaled (31) 18 . 31 = 58%. Total recruitment, defined entering population, estimated dividing yearlings summer. Recruitment adjusted mortality hunter harvest predation juveniles. first recruits (the assigned natal-area lek) correct differential marking, expressed per hour differing observation times leks, and, finally, maximum express recruitment per-male basis. References "grouse h-I male-"' refer this relative rate. bird. Estimates percentage returning biased unequally distributed summer efforts spring. natal-lek only (Gee Flats, Beaver Basin) around 50 whose closer these any other (i.e. lek). had them few mornings season. Statistical tests considered significant 0.05 probability level; 2-tailed.