Seasonal ozone and warmth gave no clear joint link to annual recorded bird-species change in US surveys in 1995-2024

We tested whether prior seasonal ozone and warmth jointly predicted annual change in recorded bird species. We used 25,140 consecutive same-route, same-observer pairs on 1,898 US Breeding Bird Survey routes. Four East and West, early and late models used route-observer and state-year effects and survey controls. The interaction estimates ranged from -0.221 to +0.263 percentage points of Jaccard dissimilarity per +10 ppb ozone and +5 C temperature. All four corrected intervals included zero. The pooled estimate was +0.164, with a 95% interval of -0.208 to +0.536. Five pooled checks gave the same broad null result. Seasonal averages, selected monitor-covered routes, few western state clusters, and imperfect bird detection limit inference. This does not establish safety or a zero causal effect. The package includes species incidence evidence, the inherited exposure panel, code, source hashes, all estimates, numerical checks and reproduction instructions.

ozone · seasonal temperature · bird species change · Jaccard dissimilarity · observation bias · Breeding Bird Survey · null result