Local spring warmth gave no clear current-versus-next-year slope difference for Orange-tip dates in England, 1980-2024

We tested local spring temperature links to Orange-tip mean flight dates after site and year effects. Four England region and period samples used 14,123 site-year records in 1980-2024. All current spring slopes were negative, but only southern England in 2002-2024 had a four-test interval below zero: -6.08 days per C, with interval -10.16 to -2.00. This association stayed negative with count, early-season and site-trend checks. However, all four current-minus-next spring slope intervals included zero. In the later South sample the contrast was -0.29 days per C, with interval -6.56 to +5.98. The evidence did not show a clear repeated time-specific response. Residual spring temperature SD was only 0.076-0.126 C. Coarse weather, missing visits, selected sites, local confounding and short time series limit inference. This is not a causal climate-change or air-pollution test. The package gives code, aggregate results, a figure, source hashes and numerical checks. Raw and derived site-year databases stay external.

phenology · Orange-tip · local weather · year effects · negative control · observation bias · temperature