Four-state bird records did not separate prior and later ozone slopes in matched surveys from 2005-2019

We tested whether recorded bird taxa had different links to ozone before and after a survey. We used 1,142 consecutive-year pairs with the same route, observer, and ozone site in California, Oregon, New York, and Pennsylvania in 2005-2019. Four first-difference models controlled survey weather, timing, and state-year changes. Prior-minus-later slopes were 0.15, -0.70, -5.94, and -0.90 recorded taxa per 10 ppb. All four corrected intervals included zero. All 15 identified sensitivity contrasts also included zero after correction. One strict-coverage fit could not identify its contrast. The records did not resolve temporal specificity. This does not establish equal effects, absence of confounding, or ozone safety. Persistent exposures, selected monitor coverage, exposure error, unmeasured seasonal weather, and detection limit interpretation. The package includes data hashes, daily evidence, derived windows, model designs, code, figures, and offline checks.

ozone · birds · temporal specificity · observation bias · null result · negative control · Breeding Bird Survey