The relative importance of intrinsic and extrinsic drivers to population growth vary among local populations of Greater Sage-Grouse: An integrated population modeling approach

Abstract

Abstract. We updated our earlier comprehensive analysis of Greater Sage-Grouse (Centrocercus urophasianus) population dynamics and probability of persistence from 1965 to 2007 throughout the species range by accumulating and analyzing additional counts of males from 2008 to 2013. A total of 89,749 counts were conducted by biologists and volunteers at 10,060 leks from 1965 through 2013 in 11 states occupied by Greater Sage-Grouse. In spite of survey effort increasing substantially (12.6%) between 2007 and 2013, the reconstructed estimate for minimum number of breeding males in the population, using standard approximations for missing values from Colorado, fell by 56% from109,990 breeding males in 2007 to 48,641 breeding males in 2013. The best model of annual rates of change of populations estimated across the Sage-Grouse Management Zones was a stochastic density dependent Gompertz model with 1-year time lags and declining carrying capacities through time. Weighted mean estimates of carrying capacity for the minimum number of males counted at leks for the entire range-wide distribution, excepting Colorado, were 40,505 (SE 6,444) in 2013 declining to 19,517 (SE 3,269) in 30 years and 8,154 (SE 1,704) in 100 years. Starting with the estimated abundance of males counted at leks in 2007 a simple effort to evaluate the validity of future forecasts of abundance was conducted by forecasting abundance in 2013 from Gompertz density dependent models with 1-year time lag and declining carrying capacity models of 6 of the 7 management zone populations. Estimated mean abundance in 2013 predicted 97.8% of the variation in true abundance in management zones. Concerted efforts across both public and private land ownerships that are intended to benefit Greater Sage-Grouse show little current evidence of success but more will be required to stabilize these declining populations and ensure their continued persistence in the face of ongoing development and habitat modification in the broad sagebrush region of western

Wildfire and the ecological niche: Diminishing habitat suitability for an indicator species within semi‐arid ecosystems

“…Shrubland recovery may be further hindered by warmer temperatures, severe drought and intensifying El Niño events that contribute to positive grass-fire feedback loops (Balch et al, 2013). Although warmer and drier sites may support sagebrush specialist species such as sage-grouse during favorable precipitation years (Coates et al, 2018) these habitats generally characterize low overall productivity and are at risk of unsustainable rates of transition to annual grass states .…”

Demographic drivers of collapse in an island population of Tree Swallows

“…In particular, IPMs can be used to estimate latent parameters such as immigration, a vital rate for which direct data are difficult to obtain (Abadi et al 2010, Schaub andFletcher 2015). Increasingly, these models are being utilized to study the demography and conservation of both widespread and threatened taxa (Zimmerman et al 2017, Arnold et al 2018, Coates et al 2018, Ross et al 2018.…”

Population and Harvest Dynamics of Midcontinent Sandhill Cranes

“…If harvest rates differed among breeding segments and between subspecies as indicated by spatial analysis of fall and wintering locations (Krapu et al 2011), then distinct groups of sandhill cranes could be increasing in numbers and others decreasing, while the entire group exhibits modest overall growth. Ignoring geographic variation in vital rates when developing population models can lead to biased growth projections (Rockwell et al 2012, Coates et al 2018). Differential harvest and vital rates have been reported in the midcontinent population of snow geese ( Chen caerulescens ) for which reduced survival rates of more southerly nesting individuals may have been caused by their earlier migration into hunted areas, which extended exposure to harvest (Alisauskas et al 2011).…”