What factors fine-tune timing of egg-laying in European starlings (Sturnus vulgaris)?

Here I investigated the role of two putative "supplemental cues", temperature and social factors, on timing of egg-laying in a local population of European starlings, Sturnus vulgaris, a highly photoperiodic and semi-colonial nesting species. A long-term temperature signal, spanning January through March, best predicted onset of egg-laying in females though there was significant residual temperature-independent variation. Social factors were only associated with this temperature-independent residual laying date, not absolute laying date. Individual variation in temperature-predicted residual laying date was associated with nearest neighbour distances in a "linear" habitat, network familiarity, and synchrony in laying though was independent of residency and female familiarity. This suggests that temperature provides a relatively long-term cue for timing of egg-laying in European starlings and that some components of social network structure could act as "supplemental cues" to fine-tune timing of laying to the local environment.