When to use social cues: Conspecific attraction at newly created grasslands

Social cues are often used by birds when selecting breeding habitats, however, little is known about the timing and influence of social cues within or across seasons. The ontogeny of social information within newly available habitat is essentially unknown and potentially relevant to habitat management, as the primary approach of many conservation initiatives is to simply create habitat. We investigated the influence of conspecific attraction via social cues (conspecific playbacks) on newly created grasslands for Grasshopper Sparrows (Ammodramus savannarum) in Central Illinois over a 2-year period. We found that Grasshopper Sparrows quickly locate and settle at newly created grasslands without the need for social cues, however, social cues are used later in the season. At sites where social cues (i.e. conspecific vocalizations) were broadcast the densities of Grasshopper Sparrows were nearly double that of sites without the additional social cues, however, this difference occurred later in the breeding season. We suggest that social cues are more valuable for Grasshopper Sparrows later in the breeding season as a potential cue of the reproductive success of individuals currently at the site, and therefore future reproduction at the site. Grassland birds are experiencing large population declines and the primary conservation approach is to provide additional habitat. By understanding how grassland birds select breeding sites we can better develop and implement conservation plans.