Prior-summer Peromyscus did not predict next-year Ixodes scapularis nymph density at 8 NEON sites in 2014–2024; a negative same-year link held at 6 high-nymph sites but not with all 8

Question: at the Cary Institute, mouse abundance in the prior summer predicts the density of questing blacklegged tick nymphs (about +40% after a strong mouse year). Does this lag occur within NEON forest sites? Two SCI publications from the same day (588f5817, 3cbdbb96) found no lag at 6 and 8 NEON sites. We found them after our analysis. This is an independent reproduction, with a plan written before we looked at the counts. It uses different indices and inference. Data: NEON RELEASE-2026 tick drag and small-mammal trapping (neonDivData; checked against raw NEON tick tables, r = 0.997). Model: within-site log–log regression of I. scapularis nymphs per 100 m2 (May–August, year t+1) on Peromyscus individuals per 100 trap-nights (June–September, year t). Results: at 8 sites (70 site-year pairs), the slope was 0.004 (95% site-bootstrap interval −0.23 to 0.16; wild cluster p = 0.96; permutation p = 0.97). Over the within-site 10th–90th percentile range of mouse years (3.8-fold), the nymph change was +0.6% (−26% to +24%). A +40% change needs a slope of 0.25. With same-year mice in the model, the prior-summer slope stayed near zero (−0.05; −0.34 to 0.21), so the same-year relation does not hide a lag. Sensitivity variants gave slopes of −0.15 to +0.12, and all intervals included zero. The control species Amblyomma americanum also showed no lag. The mouse index had a split-half reliability of 0.89. Same-year relation: at the 6 sites of SCI 588f5817, the slope was −0.48 (−0.68 to −0.31; wild cluster p = 0.007), which reproduces their result. With the low-nymph sites STEI and MLBS added, it was −0.33 (−0.56 to +0.05; wild cluster p = 0.17), although permutation p was 0.002. Limits: there are few sites and short series. Mouse grids and tick plots are at different places. The data exclude a large lag effect at the NEON within-site scale, but not slopes up to about 0.16–0.33.

Ixodes scapularis · Lyme disease · Peromyscus · NEON · tick-host dynamics · density of nymphs · lagged effects · replication · null result · small mammals · Amblyomma americanum