Spatio-temporal population dynamics of Nevada greater sage-grouse from 2000-2018
Loading...
Authors
Acevedo, Cheyenne
Issue Date
2021
Type
Thesis
Language
Keywords
Bayesian Hierarchical Model , Dynamic spatio-temporal models , lek counts , Markov chain Monte Carlo , Sage grouse
Alternative Title
Abstract
Dynamic spatio-temporal models, interfaced with long-term time-series data permit a better understanding of population dynamics across large spatial scales. The Greater Sage-Grouse (Centrocercus urophasianus) population appears to be declining across much of their range. However, there is considerable uncertainty in the spatial drivers of this decline. I developed and applied contemporary dynamic spatio-temporal statistical models to 19 years of Greater Sage-Grouse lek count data to examine spatially-explicit drivers of sage grouse population dynamics. Mean expected lek counts in Nevada declined 2.84 birds per lek between 2000 and 2018, however trends varied substantially over space, with northwestern Nevada and the Bi-State (Nevada and California) region experiencing the steepest declines (up to 6 birds per lek), and northeastern Nevada experiencing increased lek attendance. I found that elevation, total precipitation, normalized difference vegetation index, and percent sagebrush were positively correlated with expected lek counts and that drought, slope, percent bare ground, wildfire, and maximum temperatures were negatively correlated with expected lek counts. I also found that sage grouse population dynamics were closely correlated with mean precipitation the preceding 8 years. Specifically, expected lek counts tracked an eight-year precipitation average with lek attendance declining 3-4 years following 8 years of low precipitation. These results support the hypothesis that long-term mean inter-annual precipitation drives sage grouse habitat quality, and ultimately, sage grouse survival and reproduction, affecting the number of birds visiting leks the subsequent years. Finally, I provide spatially explicit maps of population trends from 2000--2018 that can support future sage grouse management and conservation.