Moth catch changes had higher correlation for the same species across 18 Finnish trap pairs 20–200 km apart in 1993–2019

We tested if annual changes in moth catches had higher spatial correlation for the same species than for other species with similar mean catch dates and mean catches. We used the Finnish National Moth Monitoring archive dated 21 October 2026. The main sample had 18 trap pairs, 20–200 km apart, at 13 locations in 1993–2019. Each pair had 18–23 changes between consecutive years. Mean Pearson correlation was 0.400 for the same species and 0.094 for matched other species. The difference was 0.306. Its descriptive 95% interval from synchronized three-year time blocks was 0.267 to 0.340. All 18 pair differences were positive. Higher count thresholds, tighter date matching, rank correlations, and removal of five outbreak moth species left a positive difference. A 95% seasonal coverage rule left no eligible pairs. Added 80% and 90% coverage checks also gave positive differences, but the stricter check had only four pairs. The result shows a strong signal associated with species identity in these catches. It does not separate population change from species-specific flight activity or trap response. The estimate and interval apply to this selected network of common species. The package preserves the raw archive, source history, sample ledgers, code, results, figures, and instructions for an offline repeat. Independent count and numerical checks passed.

moths · spatial synchrony · light traps · Finland · species identity · matched comparison · open data · sampling effort · reproducibility