Local weather scales gave no clear joint warmth and low-rainfall link to US bird counts in 1995-2024

We tested whether low rainfall made the link between previous May-June warmth and next-year bird counts more negative. We measured warmth and rainfall deficit in local county standard deviations. We reused a verified US Breeding Bird Survey panel with ozone and weather data. The main model used 24,518 surveys on 1,838 routes, route-observer and state-year effects, and survey controls. The joint term was -0.063 in 100 times log-count units per temperature SD and rainfall-deficit SD. Its 95% interval was -0.615 to +0.489. East estimates were negative and West estimates were positive in both periods. All four corrected intervals included zero. Removing ozone on the same rows gave a similar pooled estimate. A close-monitor subset also gave an interval that included zero. This extends an earlier test in fixed physical units. It is not an independent data replication or a test that isolates scaling alone. Seasonal county exposures, monitor selection, limited western data, and imperfect detection limit inference. The result does not establish safety or test daily extremes or a causal climate-change effect.

seasonal weather · bird counts · local climate variability · ozone adjustment · observation bias · robustness · null result