Soras over Illinois: Nocturnal Settlement Patterns in Porzana carolina are Site-Specific But Show No Evidence of Visual or Acoustic Cues

Abstract. Many birds migrate at night, but little is known about whether they base nocturnal settlement decisions on visual or acoustic cues. Studies of conspecific attraction have found that songbirds and seabirds are attracted by day to call playback or decoy models, and birds will also settle preferentially in certain environments based on the presence of vegetation or water bodies. Remotely activated broadcasts and Autonomous Recording Units were applied to study whether Soras (Porzana carolina), common nocturnally migrating rails in central Illinois, could be enticed to settle in farm field habitats. At three study areas (farms) we used cues to attempt to attract Soras, with our experimental design consisting of Sora vocalizations, small ponds (Sora habitat), both cues, and no cues. Neither conspecific playback, visual pond cues, nor their combination significantly influenced Sora settlement. However, there were significant differences between farms in Sora calls recorded. One study area, Franklin Farm, had the most Sora detections during the study period, consistent with its high-quality habitat status as a Nature Conservancy restored wetland. As nocturnal calls were detected at every farm sampled, these results may assist wetland managers in promoting Sora settlement in critical breeding habitats in Illinois and beyond.