Warmer dates had more usable moth samples in selected English and Scottish trap-months in 2004-2015

We tested whether daily warmth was linked to usable moth sample dates. We joined UK Environmental Change Network records to E-OBS daily mean temperature. Four models used England and Scotland in 1992-2003 and 2004-2015. The main panel had 28,572 candidate dates in 934 trap-months. Models controlled trap-year-month, trap-specific weekday, and day within month. In 2004-2015, usable sample slopes were +2.05 percentage points per C in England and +3.18 in Scotland. Four-test intervals were +1.30 to +2.80 and +1.14 to +5.23. Both earlier intervals included zero. Later slopes stayed positive under sample-count thresholds, date shifts, month-edge removal, and a recorded-effort outcome. The Scottish result depended mainly on Glensaugh. These results show weather-linked sample availability within selected months. They do not establish deliberate weather selection, moth population effects, or a change between periods. Coarse daily weather, selected active months, few sites and few year clusters limit inference. The package includes the daily panel, source hashes, code and checks. No air pollution effect is tested.

moth · observation bias · sampling availability · daily temperature · ECN · E-OBS