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We tested if UK butterflies whose larvae feed on low-nitrogen plants had more negative trends at monitoring transects with high nitrogen (N) deposition. We used 12,912 site-by-species abundance trends from 700 UK Butterfly Monitoring Scheme transects (1995-2024) and 44 resident species. Each species received the mean British Ellenberg N value of its main host plants. Each site received the CBED 1986-1995 total N deposition. A two-stage model estimated the deposition effect on site trends for each species, then a random-effects meta-regression related these effects to host-plant N. The hypothesis predicts a positive slope. The primary slope was -0.90e-3 (95% CI -1.98e-3 to 0.17e-3; species-permutation p = 0.11), opposite in sign. The independent periods 1990-2006 and 2007-2024 gave small positive slopes with intervals that included zero, so the sign did not repeat. Three latitude bands, NHx, NOx, later deposition, deposition change, other host-plant scores, a pooled two-way fixed-effects model and observation-bias checks (long or high-count series, extra site controls, site weights that match UK deposition shares) gave no hypothesis-consistent result. Sea-salt chloride, a negative control, gave a slope near zero. SOx gave the only nominal result (p = 0.02), also opposite in sign, and it does not stay significant after correction for six exposures. Thus, host-plant N preference did not predict which species declined more at high-deposition transects. Limits: observational data, non-random UKBMS sites, no public WCBS random-square indices, coarse 5 km deposition and 1 degree climate, few species, and possible N effects before 1990. The package has code, derived trends, site covariates, host-plant scores, results and figures.

Question: does atmospheric nitrogen (N) deposition cause faster decline of butterfly species whose larval host plants grow on nutrient-poor soils? JNCC Report 775 found lower butterfly richness at UK sites with high 1990s N deposition, but only in a spatial comparison. Method: we used 688,257 annual UK Butterfly Monitoring Scheme site indices (58 species, 2,961 Great Britain transects, 1986-2024), CBED modelled N deposition, and the mean Ellenberg N of each species' primary host plants. The models compare species at the same transect in the same year (site x year fixed effects) and remove regional species trends (species x 100-km square x year fixed effects). Result: the pre-specified coefficient for 1995-97 N deposition x low host N x decade was +0.018 (95% CI +0.002 to +0.035), opposite to the harm prediction (negative). Host-N and site permutation tests gave p = 0.025 and 0.019. The positive sign was not robust: it became non-significant with 50-km regional controls, a habitat-breadth control, in 2005-2024, and outside southern England. No deposition-level variant gave a negative point estimate. Deposition change (1986-88 to 2010-12) and lagged time-varying deposition (1989-2013) did not predict the trait contrast (-0.0006, CI -0.026 to +0.025). Inside 100-km squares, recorded richness was not clearly lower at high-N transects (-0.13 species per SD, CI -0.36 to +0.11); sulphur deposition took the negative association. Limitations: deposition is modelled at 5 km; historic reduced-N fields have unreliable spatial change; transects are not random and site management is not measured; 58 species give low trait-level power. Job sci-1107-dell-climate-pollution-biodiversity-27138384c947, machine dell, model Claude Opus 5.5.

Hames et al. (2002) linked high acid wet deposition to a lower probability of Wood Thrush breeding in eastern North America. US sulfate deposition then decreased: at the eastern US Breeding Bird Survey (BBS) routes in this study, the median wet SO4 decreased from 19 to 5 kg/ha/yr between 1985-1994 and 2016-2025. We did a test of the prediction that Wood Thrush counts increase most where deposition decreased most. We used the BBS 2026 release (1966-2025, 2,496 routes east of 100 W) and NADP annual deposition grids (1985-2025). Poisson models had route-observer and Bird Conservation Region x year fixed effects and an observer first-year term. Wood Thrush counts changed by +10.7% per +10 kg/ha/yr of wet SO4 (95% CI +2.2% to +20.0%; within-region permutation p = 0.028). This sign is opposite to the prediction. The estimate was at the 77th percentile of 64 other forest species, so it does not show a species-specific effect. Results stayed positive or near zero in two periods, two region groups, with NO3 in place of SO4, and with segment detections as the response. With route-specific linear trends removed, the estimate was +2.2% (-4.7% to +9.7%), which permits a recovery of at most about 5% per 10 kg/ha/yr decrease. Route trends in 1966-1998 were more positive, not more negative, where deposition was high. The SO4 effect did not change with elevation. Veery, Hermit Thrush and Ovenbird showed no consistent recovery. Limitations: BBS counts measure relative abundance, not breeding attempts; exposure is interpolated wet deposition near the route start; soil calcium recovery can be slow; and regional changes that correlate with the deposition decrease can bias the estimates.