| Populations of Greater Sage-Grouse (Centrocercus urophasianus) have declined by 69--99%. Information on population dynamics of these birds at a landscape scale is essential to informed management. I radio-collared 243 female sage grouse, monitored 287 nests and 115 broods, and measured 426 vegetation plots at 4 sites during 2001--2003 in a 3,200 km2 landscape in north-central Montana, USA. My objective was to examine the relationship between nest success, brood survival, and hen survival rates, habitat conditions, environmental variables, and hen characteristics. I used program MARK to model (1) daily survival rates of nests and broods and (2) seasonal and annual survival of hens.; Nest survival varied with year, grass canopy cover, daily precipitation with a 1-day lag effect, and nesting attempt. The best-approximating model of brood survival included effects of brood age and year, indicating substantial annual variation. Hen survival analyses indicated that survival varies by season within years and by year within seasons, that nesting hens have higher breeding-season survival than non-nesting hens, and that individuals at one site had lower hunting-season survival than hens at other sites. I observed considerable variation in hen survival. Low annual survival in 2003 is a result of the compounded effects of a West Nile virus outbreak in August of that year and a severe winter of 2003--2004.; My findings underscore the importance of large-scale approaches to conservation of sage grouse habitats and to maintenance and recovery of sage grouse populations. Management for hen survival must address hunting pressure and identification and conservation of important wintering areas. Maintaining quality habitat and a high proportion of adult hens will maximize potential for population growth when environmental conditions are favorable. |
