Design of a monitoring program to advance nightjar conservation along the Atlantic Flyway

Abstract Survey data on species in the nightjar family (Caprimulgidae) suggest declines in population abundance across their range. State and federal migratory bird managers identified the need to monitor the status of nightjars including common nighthawk ( Chordeiles minor ), chuck‐will's‐widow ( Antrostomus carolinensis ), and eastern whip‐poor‐will ( A. vociferus ) in the United States (U.S.) portion of the Atlantic Flyway as a high priority need. Previous research has determined the appropriate conditions for nightjar‐specific survey efforts, resulting in similar survey designs used in a nightjar survey network (NJN). Each species is also detected as part of the U.S. Geological Survey's Breeding Bird Survey (BBS), though this survey is not optimized for crepuscular species such as nightjars. Our objectives were to 1) examine differences in estimates of occupancy at the flyway scale derived from the NJN and BBS, 2) evaluate the probability of accurately classifying species status as a function of the number of survey routes, and 3) develop a spatial allocation of survey routes to permit accurate inference to the population. We did not find support for a negative effect of year on occupancy for any of the nightjar species using the nightjar‐specific survey data, but we found support for declines in occupancy for all 3 nightjars using the BBS data. We found all tested sample sizes (i.e., number of routes) within the Atlantic Flyway were sufficient to correctly classify increasing and declining population trends, but none could detect a slight trend. Nearly 70% of randomly distributed routes within the flyway had existing nightjar survey routes within 20 miles and >90% had existing BBS routes within 20 miles. The presence of road‐based surveys near random points allows managers to meet 2 goals: to conduct a statistically sound survey that provides information on population trends and to provide volunteer surveyors known routes to complete survey effort. We encourage development and implementation of a nightjar‐specific survey consisting of 300 randomly chosen routes in the U.S. portion of the Atlantic Flyway to monitor the status of the nightjar populations and inform management efforts. Periodic review and revision of field methodology should be made to ensure the survey is meeting stated objectives.