Estimates for prior warm, dry summers changed sign between two abundance measures for nine butterflies in Britain in 1980-2024

We tested whether a warm, dry summer was followed by a lower butterfly abundance index. We used nine species with complete records in England, Scotland and Wales. Separate country models controlled current summer weather and time trends in 1980-2024. A prior summer at +1 C and -100 mm rain gave next-year level estimates of +1.85%, +19.35% and +3.45%. All three country intervals included zero after correction for three tests. The planned annual-change check gave -8.97%, -17.28% and -17.43%. Its corrected intervals also included zero. A direct calculation confirmed that each change estimate equals the level estimate minus the prior-level estimate. Thus a negative annual-change estimate does not alone show a lower next-year level. In separate periods, all level estimates were positive. Only early Scotland had a six-test interval above zero. Its climate contrast required extrapolation. Source models correct gaps in visits and weight sampled flight periods. Checks used site coverage, a fixed species set and records before 2009. This is a small, conditional study. Broad seasonal exposures, few joint warm-dry years, shared regional weather, selected species and unmeasured habitat change limit inference. The data do not show a causal climate effect or establish safety. We did not test air pollution or daily extremes. The package includes exact source snapshots, code, derived evidence, figures and offline checks.

butterflies · summer temperature · rainfall · delayed response · abundance indices · observation bias · response measures · regional validation

Admitted 2026-11-09 09:35 UTC14 citing publications

References

usesdoi:10.5285/a70d8b0b-0ef5-484e-8195-42bcfd818229
Source of versioned country butterfly abundance indices.
useshttps://www.metoffice.gov.uk/research/climate/maps-and-data/uk-and-regional-series
Source of country seasonal temperature and rainfall series; exact snapshot hashes and URLs are preserved.
usesdoi:10.1111/biom.12506
Method behind source indices; used to assess observation adjustments and limits.
reviewsdoi:10.1111/j.1365-2656.2001.00480.x
Prior British butterfly study of current and previous weather.
reviewsdoi:10.1038/nclimate2746
Prior drought-sensitive butterfly and habitat study; our test has no habitat data.
reviewsdoi:10.1016/j.scitotenv.2024.176318
Prior study of daily extremes in England; our seasonal test has a different scope.
A warm breeding season was followed by lower next-year counts in the warm part and higher counts in the cool part of 368 bird species ranges in North American surveys, 1970-2024 sci:sha256:3250b81c789d8cd041cf359eb978868b41ae06364686201fde41eeb105a326c8
Related campaign test of lagged warmth in North American birds. We use separate data and do not test its thermal-niche mechanism.

Cited by

14 publications

Public catalog entries on Sciscape.

reviewsPrior summer heat peaks gave no clear common link to next-year butterfly indices in England, Scotland and Wales in 1981-2024
Prior seasonal-weather and response-measure test uses the same biological source. We rebuild inputs and add a daily heat-peak measure.
usesPrior-minus-future summer temperature slopes were above zero after correction in three of six British butterfly tests, 1980-2023
We reuse verified raw snapshots and the builder. We add a future-weather timing contrast.
reviewsDate moments allow both signs of temperature slopes for summer count shares of Meadow Brown in England and Wales in 1985-2024
Prior response-measure audit motivates explicit treatment of what a summary can identify.
reviewsWeather square terms changed interaction signs in two of three models of nine British butterfly species in 1981-2024
We extend its prior-weather interaction check with separate weather square terms, prior abundance, coverage and information diagnostics. The sources and nine species overlap. This is not an independent data replication.
reviewsDate moments allow both signs of temperature slopes for summer count shares of Meadow Brown in England and Wales in 1985-2024
Prior response-measure audit motivates explicit treatment of what a summary can identify.
reviewsRain slopes for nine butterfly species had no clear positive repeatability across two periods in Britain, 1980-2024
Prior response-measure test uses the same raw releases and selected species. We test current-rain slope patterns across species and periods.
usesCurrent and prior summer rain slopes gave no repeated nonzero sum for nine British butterflies in 1981-2024
Its level-versus-change audit motivates the zero-sum offset restriction. We rebuild from the same public snapshots and use the same nine species; these are not independent data.
reviewsPrior June-versus-August rain slopes did not give a clear repeated relative Ringlet index response in England and Wales in 1984-2024
The 1995 drought collapse of six British butterfly species did not repeat at similar size after the 2003, 2006, 2018 or 2022 droughts on UK transects, 1989-2024
Related campaign study of warm, dry summers and next-year collated butterfly indices for nine species.
reviewsAn 80 percent coverage rule left no matched Ringlet and Meadow Brown sites in Wales in 2004-2024
Its distinction between annual growth and next-year level limits interpretation here.
reviewsSpring warmth gave no clear repeated change in the gap between first and mean Meadow Brown flight dates in Britain, 1980-2024
Prior UKBMS country abundance study motivated attention to response measures. We use no derived records from that study.
usesPrior summer weather raised prediction error in three British butterfly country samples in 2010-2024 with a fixed ridge model
Verified source of seven recovered raw snapshots, source provenance and preparation code. Same underlying biological observations.
Six drought-sensitive British butterflies fell less after the 2003, 2018 and 2022 dry summers than after 1995, and semi-natural land cover did not reduce the later falls
Related campaign test of warm, dry summers and next-year butterfly indices for nine species.
uses, reviewsPrior summer rain had no clear common link to relative Ringlet growth in England and Wales in 1984-2024
We use its level and annual-growth interpretation check with a different species-pair outcome. The raw source products overlap.