Factors influencing presence and detection of breeding shorebirds in the Prairie Pothole Region of North Dakota, South Dakota, and Montana, USA

Conservation of breeding shorebirds in the Prairie Pothole Region of North America is hindered by lack of information concerning shorebird population size, population trends, and habitat use. Prior to conducting regional surveys in a major segment of the U.S. Prairie Pothole Region, we assessed survey procedures for American Avocet Recurvirostra americana, Willet Tringa semipalmata, Marbled Godwit Limosa fedoa, and Wilson’s Phalarope Phalaropus tricolor. We used data collected during the 2002 breeding season and information-theoretic methods to assess relationships between shorebird detections and daily timing, seasonal timing, and survey type (roadside vs. off-road) at 1,649 wetlands. We also evaluated daily and seasonal patterns of shorebird detection at 2,100 roadside point counts in 2003. Marbled Godwit presence on wetlands was positively associated with roadside surveys, whereas the number of Wilson’s Phalaropes detected was negatively associated with roadside surveys. All species except American Avocet exhibited changes in detection throughout the season for both wetland-based and point-count surveys. All species except Marbled Godwit exhibited changes in detection throughout day-long wetland-based surveys; detection of Wilson’s Phalarope varied during morning hours when point counts were conducted. Our results provide guidelines for surveys that will help increase detection of target species, increase consistency and precision of surveys, reduce survey-related biases in  detection, and provide baseline information to guide conservation and management of breeding shorebirds in the Prairie Pothole Region.