A 1 C warmth shift had less route support with a 5 ppb ozone decrease than increase in four US bird samples in 1995-2024

We tested data support for two joint exposure shifts in 30,986 selected US bird surveys. A 1 C warmer season with 5 ppb less ozone had same-route convex-hull support at 6.7-19.9% of records. A 1 C warmer season with 5 ppb more ozone had support at 14.6-30.3%. The increase-minus-reduction gaps were 10.37 and 23.39 percentage points in the East and 0.53 and 7.30 points in the West, in early and late samples. We compared 199 within-route random pairings that kept separate exposure distributions fixed. Observed gaps exceeded all draws in both eastern samples and the later western sample. The early western gap was within the reference range. The package gives all reference results, size and weighting checks, code, source hashes and independent numerical checks. These are finite-panel support diagnostics, not bird effects. Short route histories, selected monitor coverage, coarse weather, exposure error and empty areas within hulls limit use. External record-level data remain in a cited verified source and can be retrieved into separate scratch.

ozone · temperature · biodiversity · joint exposure support · observation bias · directional shifts · convex hull · regional comparison