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

Auk

Michael L. Casazza^1¹  Brian J. Halstead^1²  Brian G. Prochazka^1³  Mark A. Ricca^1⁴  Peter S. Coates^1⁵ 

[1] California Department of Fish and Wildlife, Sacramento, California, USA^5;Department of Fish and Wildlife Sciences, University of Idaho, Moscow, Idaho, USA^4;Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, Orono, Maine, USA^2;U.S. Fish and Wildlife Service, Mountain-Prairie Region, Lakewood, Colorado, USA^3;U.S. Geological Survey, Western Ecological Research Center, Dixon, California, USA^1

关键词: Bayesian analysis;    Bi-State Distinct Population Segment;    Centrocercus urophasianus;    climate;    demographic;    density dependence;    ecological scale;    environmental stochasticity;    precipitation;    random effect;   

DOI  :  10.1642/AUK-17-137.1

学科分类：动物科学

来源: Central Ornithology Publication Office

【 摘 要 】

Consideration of ecological scale is fundamental to understanding and managing avian population growth and decline. Empirically driven models for population dynamics and demographic processes across multiple spatial scales can be powerful tools to help guide conservation actions. Integrated population models (IPMs) provide a framework for better parameter estimation by unifying multiple sources of data (e.g., count and demographic data). Hierarchical structure within such models that include random effects allow for varying degrees of data sharing across different spatiotemporal scales. We developed an IPM to investigate Greater Sage-Grouse ( Centrocercus urophasianus ) on the border of California and Nevada, known as the Bi-State Distinct Population Segment. Our analysis integrated 13 years of lek count data ( n > 2,000) and intensive telemetry (VHF and GPS; n > 350 individuals) data across 6 subpopulations. Specifically, we identified the most parsimonious models among varying random effects and density-dependent terms for each population vital rate (e.g., nest survival). Using a joint likelihood process, we integrated the lek count data with the demographic models to estimate apparent abundance and refine vital rate parameter estimates. To investigate effects of climatic conditions, we extended the model to fit a precipitation covariate for instantaneous rate of change ( r ). At a metapopulation extent (i.e. Bi-State), annual population rate of change λ ( e^r ) did not favor an overall increasing or decreasing trend through the time series. However, annual changes in λ were driven by changes in precipitation (one-year lag effect). At subpopulation extents, we identified substantial variation in λ and demographic rates. One subpopulation clearly decoupled from the trend at the metapopulation extent and exhibited relatively high risk of extinction as a result of low egg fertility. These findings can inform localized, targeted management actions for specific areas, and status of the species for the larger Bi-State.

【 授权许可】

CC BY