Catch dates showed an uncertain mean advance for nine ground beetle species at six UK sites in selected 1994–2015 records

Did ground beetle catches move earlier in the year at fixed recorded transects? We used open UK Environmental Change Network data and compared selected years within 1994–2003 and 2006–2015. We split catches and effort across calendar months from the reported trap-setting intervals. A fixed seasonal window and coverage filters left 28 transect–species pairs, nine species, 14 transects, and six sites. Species had equal weight within transects, transects within sites, and sites in the mean. The mean catch date was 7.3 days earlier. The 95% interval across site means was 19.7 days earlier to 5.2 days later. Resampling sites and shared two-year time blocks gave 18.7 days earlier to 1.3 days later. Removing North Wyke reduced the estimated advance to 2.7 days. At one North Wyke pair, a change from autumn toward spring catches caused a large mean date change. All planned filter checks left the mean change uncertain. The result concerns catches in May–October, which depend on both numbers and movement. It does not establish earlier emergence or a UK-wide climate effect. The package preserves raw data, provenance, source audits, selection ledgers, code, figures, and independent checks.

ground beetles · seasonal timing · pitfall traps · Environmental Change Network · sampling effort · reproducible ecology