Spring warmth gave no repeated decrease in the Orange-tip northing gradient in England in 1980-2024

We tested whether warm springs reduced the north-south gradient in Orange-tip mean flight dates. Four site and year models used 13,951 site-years in northern and southern England in 1980-2001 and 2002-2024. The models controlled winter warmth, a spatial time trend and peak count. Early estimates were +1.80 and +1.39 days per 100 km per C. Later estimates were +0.05 and -0.03. One early northern interval excluded zero after four-test correction, but this result did not persist with stricter site coverage or an east-west weather term. The evidence gives no repeated decrease in the gradient. It does not show no spatial response or a change between periods. Missing visits, selected sites, coarse weather and few years limit inference. The package gives source hashes, a data panel, all 28 model fits, code, a figure and separate coefficient checks. It tests no pollution effect.

phenology · Orange-tip · spatial gradient · spring temperature · observation bias · UKBMS · regional replication