Conspecific cues and breeding territory selection in Whinchat on abandoned fields

Abstract

Many bird species use social information to guide territory selection. Different species in different habitats may use both pre-breeding and post-breeding conspecific cues. Abandoned agricultural fields are of particular interest for studies of conspecific attraction because the ephemeral nature of the habitat suggests territory search just before breeding, but high predation pressure suggests the use of performance-based conspecific cues. We investigated whether post-breeding or pre-breeding social cues affect Whinchat (Saxicola rubetra) abundance at the territorial scale during a two-year experiment in abandoned fields. We assigned 27 experimental plots (3.14 ha) to one of three treatments: post-breeding treatment, pre-breeding treatment and silent control. We conducted playback experiments with fledgling calls (evidence of past reproductive success) during the post-breeding period and male songs (evidence of conspecific presence) during the pre-breeding period. We estimated the difference in Whinchat abundance in two consecutive years and tested whether this value differed between treatment and control plots. We observed a slight increase (0.67 ± 0.29 pairs per plot) in Whinchat abundance in the post-breeding treatment plots and no significant changes in the pre-breeding (−0.22 ± 0.32 pairs per plot) and control (−0.22 ± 0.22 pairs per plot) plots. Our results suggest that Whinchats do not use conspecific acoustic cues during the pre-breeding period and provide limited evidence for the use of fledgling calls as conspecific cues in the post-breeding period.