Volunteer Observer Bias and Sharp-Tailed Grouse Lek Counts in the Upper Midwest

Abstract

Abstract For most species of prairie grouse Tympanuchus spp. standardized monitoring protocols do not exist across adjoining jurisdictions. For instance, researchers monitor relatively small and disjunct populations of prairie sharp-tailed grouse Tympanuchus phasisanellus campestris in Michigan, Wisconsin, and Minnesota using different lek count protocols. Some of these state-led monitoring efforts include the widespread use of volunteers who conduct lek counts without training. To facilitate discussions regarding standardizing sharp-tailed grouse lek count protocols in the Upper Midwest and elsewhere, we quantified the magnitude of differences in data arising from lek counts conducted by paired observers and examined factors potentially associated with observer bias (e.g., training type, use of optical equipment, experience). During 2010–2015, 44 unique pairs of formally trained volunteers in the Upper Peninsula of Michigan performed 93 counts at one lek while controlling for weather, distance to the lek, and the timing of observations. All counts consisted of six 1 min observations over 1 h. At three leks in northeastern Minnesota during 2015, nine pairs (consisting of an individual new to lek counts and a more experienced biologist) performed 21 lek counts using the same protocols, but without formal training for novice observers. Across all years and all sites, our results consistently indicated more agreement in data for dancing birds than nondancing birds. Overall, the mean ± SE difference between paired observers for total birds (dancing and nondancing combined) was 1.05 ± 0.09 in Michigan and 0.37 ± 0.08 in Minnesota. Generalized linear models indicated that the use of optical equipment and training type for dancing birds and training type for nondancing birds were significant factors that improved data agreement in Michigan. In Minnesota, models indicated that experience level (number of surveys performed) of the technician or volunteer did not affect count differences for dancing birds or nondancing birds. We contend that using behavior as a proxy for sex can bias lek count data for sharp-tailed grouse. We suggest lek count protocols in the Upper Midwest be simplified and standardized. Specifically, we suggest that observers report the total number of observed birds (regardless of behavior) and that protocols establish a set duration of observation. We also suggest that the use of optical equipment be required and that training be mandatory.