Contemporary greater prairie-chicken habitat distribution change and landscape thresholds in Kansas
Grassland bird monitoring efforts continue to document population declines in the Great Plains, USA and there is limited understanding of how declines are associated with landscape changes over broad scales. Within Kansas, USA, surveys indicate the resident grassland obligate greater prairie-chicken ( Tympanuchus cupido ) declined during the past 30 years. Grassland loss has been cited as the main driver of the decline; however, other factors including pesticide application, woody encroachment, and anthropogenic vertical structures are likely attributable. To evaluate, we used a random forest modeling approach to compare grassland cover, woody cover, and pesticide use between occupied ( n = 5552) and “pseudoabsent” ( n = 11,223) greater prairie-chicken lek site locations from 1993 to 2020. Our best-supported variables were grassland within 5 km, woody cover within 800 m, and pesticide application within 5 km of lek locations. The model correctly predicted the use or absence of leks with 89.95% accuracy based on independent validation. Our analysis suggests that grasslands have become aggregated within a 5 km radius where woody encroachment is less pronounced in the Smoky Hills and Northern High Plains management units and therefore landscapes have become more favorable for greater prairie-chickens at this scale. In contrast, the Flint Hills management unit netted a 13% loss of greater prairie-chicken habitat coinciding with woody encroachment and increased pesticide use. For 2020, we predicted a further loss of functional habitat from the presence of wind turbines, power transmission lines, and oil and gas infrastructure using previous literature documenting scales of avoidance. Our results support hypotheses that grassland loss, woody encroachment, and pesticide use all present negative population consequences for greater prairie-chickens. Current trends may be altered with grassland conservation action that seeks to conserve grasslands with < 10% woody cover and minimal pesticide use.