ANNUAL AND SEASONAL VARIABILITY IN LEK ATTENDANCE RATES OF GREATER SAGE-GROUSE IN NEVADA

Gregory T Wann; U.S. Geological Survey; wanng@usgs.gov; Peter S. Coates, Brian G. Prochazka

Counts of males displaying on breeding grounds are commonly used to assess population trends in lekking grouse species. Lek attendance (i.e., the proportion of males on leks available for detection) is thought to be a major contributing factor to variation in counts. However, attendance rates are rarely quantified. We assessed attendance rates of greater sage-grouse (Centrocercus urophasianus) at eight study sites in Nevada to better understand the utility of lek counts as an index to population abundance. We used daily location data collected from 81 male sage-grouse marked with global positioning system (GPS) transmitters over five lekking seasons (2013-2017) to estimate seasonal and annual variability in attendance rates using generalized additive models and lek boundaries mapped following lek counts. Average timing of peak attendance occurred on 8 April but varied from 20 March (2014) to 17 April (2016). Average peak attendance was 54.0% and varied from 25.4% (2015) to 74.4% (2017). Overall, adult males attended leks at higher rates (63.2% at peak) and earlier in the season (peak on 5 April) than subadults (31.7% at peak on 24 April). Our results indicate attendance rates are more variable than previously thought and provide new insights on individual behavior during a critical monitoring period.

Ecology and Conservation of Birds II