Spring rain gave no clear repeated link to paired butterfly flight timing in England in 1985-2024

We tested whether spring rain was linked to the mean flight-date gap between Orange-tip and Green Hairstreak butterflies at the same English sites. Four region and period models used 263 paired site-years at 15 sites in 1985-2024. Models removed stable site differences and controlled spring and winter temperature and linear time. Rain slopes ranged from -1.14 to +2.70 days per 100 mm. All four corrected intervals included zero. Raising the count threshold retained only three sites, gave opposite southern slope signs between periods and left one northern model without residual degrees of freedom. A future-rain check gave a nominal association in the later southern period. The tests do not establish a stable rain response. Sparse selected records, missing visits, country weather and short annual series limit inference. The regions have separate sites but share the same weather series. This does not identify a causal climate or pollution effect. Code, aggregate results, source hashes and a figure are included; external records remain outside the bundle.

phenology · butterflies · rainfall · paired sites · observation bias · null result · regional replication