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Evaluation of Alternative Population Monitoring Strategies for Greater Sage-Grouse in the Parachute-Piceance-Roan Population of Western Colorado
Evaluation of Alternative Population Monitoring Strategies for Greater Sage-Grouse in the Parachute-Piceance-Roan Population of Western Colorado

​​​​​Led By

Jessica Brauch (Colorado State University), Barry Noon (Colorado State University), Brett Walker​ (CPW)

Study Area

Rio Blanco and Garfield counties

Project Status

Field data collection is complete. Data analysis and preparation of manuscripts for publication is on-going.

Research Objectives

  • Estimate the proportion of known leks and the total number of male greater sage-grouse attending leks in the population over  3 breeding seasons using dual-frame helicopter sampling of leks
  • Estimate population size and sex ratio using non-invasive, genetic mark-recapture methods during two consecutive winters
  • Compare and contrast dual-frame sampling of leks and genetic mark-recapture with standard lek counts as methods for estimating sage-grouse population size and trends

Project Description

Robust estimates of population size and population trends provide the scientific basis for managers to make appropriate and defensible recommendations regarding land-use decisions, harvest regulations, and mitigation efforts for wildlife. When linked with environmental variables, robust monitoring programs also allow managers to examine wildlife responses to various stressors. However, many wildlife monitoring programs continue to use population indices that may or may not provide reliable information on population status or trends. For this reason, it is essential to evaluate alternative approaches to population monitoring in terms of estimator precision, cost, practicality, and level of disturbance. Lek counts are the primary index used by state wildlife agencies to monitor changes in greater sage-grouse abundance, but current lek-count monitoring relies on untested assumptions about lek attendance, detectability, inter-lek movement, sex ratio, and the proportion of leks that are known and counted. Given the availability of new methodological and statistical approaches to estimate wildlife populations, it is worth comparing the performance of current lek-count approaches versus other estimation methods. 

Dual-frame sampling of leks and non-invasive genetic mark-recapture analyses based on winter pellet sampling are promising alternatives for monitoring trends in sage-grouse populations. The purpose of this study is to evaluate and compare the reliability and efficiency of dual-frame lek sampling with helicopters, non-invasive genetic mark-recapture sampling, and standard lek counts for estimating population size and trend and to estimate sex ratio in the Parachute-Piceance-Roan population in NW Colorado. Field data collection was conducted from fall 2011 to spring 2014. For dual-frame sampling, we are using occupancy modeling to account for imperfect detectability of leks in each sampling frame. We are analyzing pellet samples collected in winter 2012-2013 and winter 2013-2014 to derive genetic data for mark-recapture and spatial mark-recapture analyses to allow us to estimate sex-specific abundance for the population in each year.