Home Range Size and Movements of Greater Prairie-Chickens

Size of a home range is key to a species' conservation and management. Estimates of home range size vary with movement patterns, which in turn vary with sex, age class, season, time of day, and habitat configuration, particularly extent of fragmentation. We describe variation in home range and movements in a grouse endemic to North American prairie, the Greater Prairie- Chicken (Tympanuchus cupido pinnatus). Our study area included a large, contiguous block of tall- grass prairie. We found that daylight movements varied with time of day: typically, birds were least active in the heat of midday and most active in the relative cool of morning and evening, a pattern consistent with sunrise and sunset, particularly in autumn, winter, and spring. The species' lek and nesting biology predicted observed lulls in male movement in spring and female movement in summer; sexes are equally mobile at other seasons. Females had larger home ranges than males, moved more frequently between activity centers, and moved greater maximum distances; therefore, females may be more susceptible to the negative effects of habitat fragmentation. Yearlings of both sexes tended to move more than adults. A synthesis of home range estimates from our work and past studies suggests there may be an inverse relationship between habitat continu- ity and home range sizes. Our results underscore the need to consider various environmental and other factors when estimating home range size. We also present preliminary evidence that habitat fragmentation may force prairie grouse to expand their home range, potentially decreasing survivor- ship through increased mortality from predation risk or energy expenditure.