Previous-season ozone gave no clear change in warmth slopes of bird community temperature index in US surveys in 1995-2024

We tested whether previous-season ozone changed the link between seasonal warmth and the temperature preference of recorded bird communities. We joined two published panels from the US Breeding Bird Survey. The pooled model used 31,303 visits on 2,021 routes in 1995-2024. It had route-observer and state-year effects and survey controls. The ozone by warmth term was -0.0031 C of community temperature index per +10 ppb ozone and +2 C warmth, with a 95% interval of -0.0118 to +0.0057. Four separate East and West, early and late samples gave mixed signs. All four adjusted intervals included zero. Other fixed effects, closer current-year monitors, removal of first observer years, and route trends did not establish a common effect. The result does not show that ozone has no ecological effect. Seasonal means do not measure daily extremes. Coarse exposure data, selected routes, unknown detection, fixed species temperature values, and few western state clusters limit inference. The package has the joined data, code, exact source hashes, full results, and an independent solver check.

ozone · community temperature index · bird communities · seasonal warmth · observation bias · regional replication · null result