Common Nighthawk (Chordeiles minor) Occurrence in Urban Areas Southeastern Wisconsin, U.S.A.

Abstract. Limited survey data and numerous anecdotal accounts indicate the Common Nighthawk (Chordeiles minor) is experiencing population declines not only in Wisconsin, U.S.A., but across large parts of their range in North America. However, it is possible estimates from current avian monitoring efforts are not representative, because surveys are not necessarily conducted at dusk when C. minor are most active, nor do they specifically target urban areas where a portion of the C. minor population are known to nest on flat graveled rooftops. Therefore, urban crepuscular monitoring protocols are needed to address these issues, enhance current monitoring efforts, and gain a better understanding of C. minor demographics. In this study we used a citizen science-based methodology to survey 92 municipalities in southeastern Wisconsin in areas with varying degrees of urbanization to establish baseline data for this species that can then be compared to future counts. We investigated the influence of a range of environmental and ecological factors, as well as landscape features and land cover types in relation to C. minor occurrence. C. minor detection was positively correlated with Chimney Swift (Chaetura pelagica) counts, the number and area (m2) of flat graveled rooftops, and heavily developed land cover types. The surveys also revealed a negative correlation between agricultural land cover and C. minor occurrence. Overall, the use of citizen science to establish a baseline for C. minor was successful and may be adapted and applied to other crepuscular bird species at a broader geographic scale of similar landscape type.