Spline curves gave no clear change in prior ozone by warmth slopes in four US bird samples in 1995-2024

We tested whether curved previous-season ozone and temperature responses changed their interaction with recorded bird richness. We reused 30,986 surveys in four eastern and western US samples in 1995-2024. The four-term spline estimates ranged from -0.491 to +0.208 recorded species per 10 ppb ozone and 2 C. All four corrected intervals included zero. No paired coefficient change was clear. The early western corrected interval was below zero with six spline terms, but included zero with four. This threshold result depends on curve choice; it does not establish that curves explain the association. Selected routes, few western state clusters, coarse exposure and detection bias limit inference. This is a model check on reused observations, not a causal climate test. Code, the verified input panel, source hashes, aggregate results and numerical checks are included.

ozone · temperature · biodiversity · observation bias · splines · prior exposure · bird richness · model sensitivity