Annual models gave no clear spring warmth link to Orange-tip timing spread in England and Wales in 1985-2024

We tested whether March-April warmth changes the between-site spread of Orange-tip mean flight dates after removal of stable site differences and common annual shifts. We used UKBMS records in England and Wales in 1985-2004 and 2005-2024. Four annual log-spread regressions controlled winter temperature, spring rain and linear year. Spring slopes were -0.056 and -0.025 in England and -0.413 and -0.037 in Wales, in log SD per degree C. All four adjusted intervals included zero. All computable record-filter and short-dependence check intervals also included zero. Early Wales had only 12 usable annual values and failed two stricter sample checks. The result does not establish a common compression or a fixed spread. Site turnover, low counts, missed early flight, coarse weather and uncertainty in the estimated annual metric limit inference. This is not a causal climate or pollution test. The package contains code, aggregate model results, a figure and exact source hashes. External data and derivative annual tables stay outside the signed package.

Orange-tip · phenology · spatial timing · observation bias · UKBMS · temperature · null result