The role of environmental stochasticity on population demography of greater sage-grouse in central Nevada, U.S.A.

Abstract

The response of population vital rates to environmental variability drives the dynamics of populations, such as population growth and fitness. The magnitude to which a population is influenced by its environment is also variable and is related to the relative influence of density dependent (e.g., intra-species competition) and density independent (e.g., weather) environmental forces currently acting on a population. At the individual level, vital rates strongly associated with fitness are predicted to be buffered to a certain extent from environmental variability through processes such as behavior. My dissertation used data collected from a ten year study of sage-grouse populations in Eureka County, Nevada, USA from 2003-2012. My first chapter introduces concepts associated with how individuals and populations respond to environmental variability. My second and third chapter examine the spatial and temporal relationships between habitat selection and reproductive success. The second chapter focuses on determining if nest site habitat selection remains adaptive for female sage-grouse, whereas the third chapter assesses if patterns in reproductive success and habitat selection covary with weather. Together, these chapters assessed whether female sage-grouse reproductive behavior (i.e., habitat preferences) remain adaptive, or positively associated with reproductive success, and if weather, which has been supported to influence recruitment of individuals into the breeding population, influenced these habitat preferences. My final research chapter is a comprehensive assessment of the influence of the indirect effects of transmission lines on sage-grouse demography. Together, my dissertation provides insights into how sage-grouse populations respond to environmental variability, as well as to predicted changes to the environment (e.g., climate change), which should provide land practitioners with much needed information to establish effective management strategies.