Detectability of lesser prairie-chicken leks: A comparison of surveys from aircraft

Lesser prairie-chickens (Tympanuchus pallidicinctus) are traditionally monitored by spring road-based lek surveys and counts of males attending leks. Several weaknesses exist with ground-based monitoring methods such as the bias of restricting surveys to roads, unknown probability of lek detection, and man-hours required to survey large tracts of habitat. We evaluated aerial surveys to locate lesser prairie-chicken leks in Texas and New Mexico using a Cessna 172 airplane (C172), R-22 Beta II helicopter (R-22), and R-44 Raven II helicopter (R-44) during spring 2007–2008. We determined lek activity during surveys with remote cameras placed on leks and cross-referenced time on the photo frame to time on our Global Positioning System flight log. From remote cameras we found that 305 leks were available for detection during survey flights. We determined lek detectability was 32.7% (95% CI = 20.3–47.1%) in the C172, 72.3% (64.50–79.14%) in the R-22, and 89.8% (82.0–95.0%) in the R-44. We created 16 a priori logistic regression models incorporating aircraft platform, distance to lek, survey date, lek size, and lek type to explain lek detection from aerial surveys. Our top ranked model included platform, distance, and lek type (model weight; w_i = 0.288). We had four competitive models and model averaged to draw inferences. Model averaging showed that detectability was generally greatest with the R-44, followed by the R-22, and lowest with the C172, with a slight deviation from this ranking at increased distances. Within our transect width, model averaging also suggested that detectability decreased as distance from the transect to the lek increased during helicopter surveys, and detectability increased as distance from the transect to the lek increased during C172 surveys. Furthermore, man-made leks were more likely to be detected than natural leks and large leks were more likely to be detected than medium or small leks. Aerial surveys effectively locate new leks and monitor lek density, and alleviate weaknesses associated with ground-based monitoring. We recommend using the R-44 to conduct lek surveys while flying at an altitude of 15 m at a speed of 60 km/hr on sunny mornings. © 2011 The Wildlife Society.     

Responses to land cover and grassland management vary across life‐history stages for a grassland specialist

Grassland birds have exhibited dramatic and widespread declines since the mid‐20th century. Greater prairie chickens (Tympanuchus cupido pinnatus) are considered an umbrella species for grassland conservation and are frequent targets of management, but their responses to land use and management can be quite variable. We used data collected during 2007–2009 and 2014–2015 to investigate effects of land use and grassland management practices on habitat selection and survival rates of greater prairie chickens in central Wisconsin, USA. We examined habitat, nest‐site, and brood‐rearing site selection by hens and modeled effects of land cover and management on survival rates of hens, nests, and broods. Prairie chickens consistently selected grassland over other cover types, but selection or avoidance of management practices varied among life‐history stages. Hen, nest, and brood survival rates were influenced by different land cover types and management practices. At the landscape scale, hens selected areas where brush and trees had been removed during the previous year, which increased hen survival. Hens selected nest sites in hay fields and brood‐rearing sites in burned areas, but prescribed fire had a negative influence on hen survival. Brood survival rates were positively associated with grazing and were highest when home ranges contained ≈15%–20% shrub/tree cover. The effects of landscape composition on nest survival were ambiguous. Collectively, our results highlight the importance of evaluating responses to management efforts across a range of life‐history stages and suggest that a variety of management practices are likely necessary to provide structurally heterogeneous, high‐quality habitat for greater prairie chickens. Brush and tree removal, grazing, hay cultivation, and prescribed fire may be especially beneficial for prairie chickens in central Wisconsin, but trade‐offs among life‐history stages and the timing of management practices must be considered carefully.