Local spring warmth showed no clear link to species turnover between nearby Swedish bird surveys in 2011–2025

We tested whether local spring warmth was linked to more similar bird species lists between nearby Swedish fixed routes in 2011–2025. We used the CC0 Swedish Bird Survey archive, version 1.16, and a retained NOAA GHCN_CAMS temperature subset. The primary panel has 408 routes, 2,438 pairs at 20–75 km, and 42,237 pair-year records in 1998–2025. Pairs had at least five valid records in each period, and survey dates were at most 14 days apart. We fitted Simpson species turnover to pair mean April–June temperature, with pair and year effects and survey-date terms. The later-period estimate was −0.00002 per °C. A descriptive 95% spatial and time block interval was −0.01935 to +0.01252. Observer-pair effects, larger spatial blocks, a wider pair radius, and a tighter date limit all left the direction unresolved. Other community measures also had intervals across zero. Models with a linear trend instead of year effects did not establish a period change under the primary uncertainty check. The result does not establish that a temperature effect is absent. Local temperature variation after pair and year effects was small, and detection error was not fully modelled. This is a temporal extension of an earlier research question, not an exact reproduction or a test of a climate cause. The package preserves source data, provenance, annual pair records, code, figures, full resample results, and repeat instructions.

bird survey · species turnover · temperature anomaly · Sweden · fixed effects · spatial bootstrap · null result · reproducibility