Research on social factors as cues for timing of egg-laying have focused on the roles of male song and display. Although male and female song can have similar functions (e.g. competition mediation, intra-pair communication, predator defence, territoriality), female song is still poorly understood. Recent studies demonstrate benefits of female-female interactions and synchrony of egg-laying, including gaining information on environmental conditions, matching food availability with provisioning, group foraging to locate food, and stimulation of ovarian development and reproductive behavior. Positive social interactions between females might therefore fine-tune laying date, increase breeding synchrony, and enhance reproductive success, whereas negative female social interactions (stress, territorial aggression, nest box takeovers) will likely disrupt social networks and breeding synchrony. In European starlings (Sturnus vulgaris), highly social birds that exhibit semi-colonial living and synchronous breeding behaviors, spring temperatures predict timing of egg-laying, but in some years actual and predicted laying dates deviate significantly. I will use social network analysis including proximity to, and familiarity with, other females, to determine if female social interactions explain residual variation in laying date at both the individual and population level. Ultimately, I plan to experimentally investigate the relationship between female social interactions and timing of breeding. I will use a compilation of pre-breeding female vocalizations recorded at nest boxes to conduct a female-specific song-playback aiming to manipulate laying date by inducing positive social stimulation (advancing laying) or negative social stimulation (delaying laying date).