The mean baseline latitude score decreased in scored moth catches at 26 Finnish traps between 2003–2009 and 2013–2019

We tested whether moth species recorded farther south in an earlier survey gained weight in later catches at fixed Finnish traps. We estimated species latitude scores from 1993–2002, excluding training locations within 100 km of each test trap. Scores required records at five training locations. We compared 300 eligible trap-years at 26 fixed traps in 2003–2009 and 2013–2019. The mean score within scored catches decreased by 0.0943 degrees. Twenty traps had a decrease. The conditional joint 95% spatial and year-block interval was −0.1826 to −0.0059 degrees. A check with equal expected species weights at 300 moths also gave a decrease. Some planned checks included zero. Scores covered 90.5% of catches on average, but only 34.9% in the least-covered trap-year. Exact bounds for the whole catch were −0.2972 to +0.1269 degrees if each unscored species could have any fixed score within the baseline latitude range. Thus the whole-catch direction remains uncertain. This is a change in scored light-trap composition, not an estimate of range movement or a climate effect. We preserve the source archive, source code, scores, all checks, figures and reproduction instructions.

moths · Finland · species distribution · community composition · latitude score · light traps · independent test periods · reproducible research