At six NEON forest sites (2014–2024), county weather did not explain the negative same-year relation of Peromyscus and Ixodes scapularis nymph indices, and no within-season host removal was seen

Question: SCI 588f5817 found no lag-1 relation between summer Peromyscus abundance and next-year Ixodes scapularis nymph density at six eastern US NEON sites (2014–2024), but found a negative same-year relation that it did not explain. We tested two causes: summer weather that moves the two indices in opposite directions, and cumulative removal of questing nymphs by hosts. Approach: An independent pipeline (Poisson GLM site-year indices from neonDivData RELEASE-2026 tables, site fixed effects, within-site permutation tests) first reproduced 588f5817: lag-1 elasticity +0.03 (95% CI −0.25 to +0.31), same-year −0.45 (−0.73 to −0.17), 62 site-years. With a plan written before calculation, we added NOAA nClimDiv county weather and split the nymph season into May–June and July–August. Results: The same-year slope did not change with May–August Tmax and precipitation (−0.45), winter Tmin (−0.47), and year fixed effects (−0.47, 95% CI −0.78 to −0.16). Warmer summers had higher mouse indices (+0.29 log units per °C, p = 0.02), but nymph indices had no significant relation with weather. The cumulative-removal prediction failed: log(late/early nymph index) did not decrease with mice (+0.07, −0.27 to +0.41). The negative relation was already present in May–June (−0.43, p = 0.008). Post hoc, on 43 common site-years, May–June nymphs had a negative relation with mice trapped in August–September (−0.33, p = 0.03) but only a weak relation with mice trapped in April–May (−0.08, −0.34 to +0.18), which does not fit removal by the counted mice. Conclusion: The tested county weather variables do not explain the relation, and it does not show cumulative within-season host removal. A driver that acts before the season (for example, acorn crops), multi-year cycles, or chance remain possible; NEON has no acorn or deer data. Limitations: six sites, 7–11 years each, county-scale weather, a ratio test that cannot detect fast steady-state removal, and a post hoc window comparison.

Ixodes scapularis · Peromyscus · Lyme disease · tick nymph density · NEON · host removal · weather · nClimDiv · reproduction · neonDivData · same-year association