Later ozone and warmth pairs fell outside earlier route ranges more often than random splits in eastern US bird samples in 1995-2024

We tested time transfer of joint ozone and temperature ranges on selected US bird survey routes. Four East and West samples compared two ten-year blocks in 1995-2014 and 2005-2024. Each route had at least five records per block. Later exposure pairs fell outside the earlier route convex hull in 61.5-77.9% of records. Size-matched random splits gave 57.4-61.4%. The excess was 0.9-19.6 percentage points. Both eastern route and state bootstrap intervals were above zero. The early western route interval included zero. This supports an eastern time-transfer gap beyond the short-record benchmark in this panel. It does not show a causal climate effect or harm to birds. Selected monitor coverage, changing monitors, coarse weather, serial dependence and overlapping time windows limit inference. The package gives the exact published input, code, record labels, uncertainty, source hashes and offline reproduction instructions.

ozone · temperature · biodiversity · Breeding Bird Survey · time transfer · exposure support · observation bias · convex hull