Based on individual nest site temperature measurements at an upland study area in Central England, this study demonstrates spatial temperature plasticity in breeding timing at the local territory level by which Common Redstart (Phoenicurus phoenicurus) and two sympatric Paridae can track food resources during breeding, and similar interannual temperature-related plasticity. The quantitative plasticity estimates are in the range of -4 to -7 days/°C, at the upper end of the range of values previously reported, or steeper. In addition, the study provides evidence of phenological constraints on Redstart breeding related to the timing of return migration in the spring. Redstarts forego otherwise suitable breeding habitat employed by sympatric residents where spring has advanced beyond a certain stage. At the territory level at a fine scale, they select cooler breeding sites which are less phenologically advanced when they return, avoiding warmer lower lying and south facing areas where breeding activity by residents has already commenced. Redstart fledging success was high with chicks fledged from 87% of eggs hatched, excluding predations and similar losses, suggesting that trophic asynchrony has little impact on breeding productivity. These observations of preferential settlement are set against the background of a decline in this species across the southerly edge of its UK range. They suggest that rather than trophic asynchrony in philopatric populations driving declines at the warmer edge of the range under climate change, a more active mechanism for range shift may apply. It appears that settlement is influenced by climatic conditions, whereby individuals select breeding territories based on phenological criteria in the areas they encounter, maintaining a climatic niche. Finally, the discrepancies between the quantitative estimates for plasticity determined in this study and others in the literature raise questions about the reliability of the regression models employed that deserve further attention.

The interannual variation in arrival timing of Whitethroat in England is strongly correlated with temperature and wind speed at locations to the south, along the migration route through Europe, with higher temperatures and lower wind speed, in particular at more northerly sites in France, associated with earlier arrival. Analysis of en route weather conditions demonstrates significant warming and wind stilling during the migration period in recent years, suggesting a potential role for amelioration of weather conditions in the observed advancement trend of arrival. When linked to the meteorological trends, quantified reaction norms derived from the interannual variations indicate that perhaps close to half of the recently observed arrival advancement for this species might be explained by plasticity of this sort. According to this mechanism, less favourable weather conditions that were previously more prevalent will have retarded progress during migration to a greater extent prior to recent climate change-dependent amelioration of the weather which now reduces delays to onward migration. However, the wider literature indicates that there has been advancement of Mediterranean passage of long-distance passerine migrants of a similar magnitude as the advancement of Whitethroat arrival in England, suggesting a limited role for this proposed mechanism. Earlier arrival in these European passage areas may offset the potential for further advancement due to warmer temperatures and lower wind speeds. It may mean that birds will continue to encounter similar meteorological conditions as was previously the case but, having advanced passage of the Mediterranean, slightly earlier in the year and so providing for progress through Europe at a broadly similar, meteorologically moderated rate. Amelioration of en route weather conditions may still make an important contribution to arrival advancement since, without it, earlier arrival in Europe could result in increased delays to onward migration.