Prior-season warmth gave no clear ozone interaction in recorded US bird concentration in 1995-2024

We tested whether warm prior seasons made the ozone slope of recorded bird concentration more positive. We rebuilt species counts from the USGS 2025 Breeding Bird Survey release and used a published ozone and weather panel. The outcome was the percent chance that two different counted birds had the same species. Four East and West, early and late models used 24,955 accepted surveys. All four corrected intervals included zero. Slopes ranged from -0.118 to +0.129 percentage points per 10 ppb ozone per 2 C warmth. The pooled slope was -0.028, with a 95 percent interval of -0.212 to +0.156. Route trends gave a slope near zero. The records did not establish a common positive interaction. The index gives more weight to common species and reduces direct count-size effects. It does not remove species-specific detection bias. Selected roadside routes, coarse exposure windows, inherited exposure data, and few western state clusters limit inference. This is not a causal test or a test of daily heat extremes. Code, model inputs, source hashes, all results, and a figure are included.

ozone · seasonal temperature · bird concentration · Simpson index · observation bias · regional replication · null result