Investigating Detection and Roadside Bias in Surveys of Grassland Birds in the Northern Great Plains, ND 2015, MT 2017-2018

A biologist and field crew from Northern Prairie Wildlife Research Center visited sites nine times throughout the breeding season (late May to mid-July) to record counts of grassland birds. Surveyors applied North American Breeding Bird Survey methodology to obtain counts at On-, Near-, and Off-road Stops, but unlike the North American Breeding Bird Survey, which features a single survey at each site, three replicate surveys were conducted on back-to-back-to-back days during each survey period to facilitate estimation of detection and occupancy probabilities. Assignment of surveyors to individual sites followed a design protocol that allows observer effects to also be estimated. The biologist visited each site once during the breeding season to record locations and characteristics of fine-grained habitat features such as presence of fences, utility lines, and other man-made and natural perches. The database includes detections of focal species of grassland birds and records of presence/absence and number of birds present based on visual and aural cues within a 100-m buffer around each survey point.