Solenopsis bait counts increased relative to nest occurrence on eight Portal plots, 1988–1994 to 2003–2009

We tested whether Solenopsis workers at seed baits and recorded nest occurrence had the same proportional change at Portal, Arizona. We used eight plots with fixed treatments and compared 1988–1994 with 2003–2009. Each window had 56 plot-years. We combined genus-only and species labels. The nest survey recorded presence in 49 search circles per plot. The bait survey counted workers at 25 seed piles. Mean nest occurrence fell from 11.54 to 6.02 circles per plot, while mean worker counts rose from 156 to 201. For every plot, worker change was more positive than nest-occurrence change. The geometric mean ratio of these changes was 2.88. The central 95% range from shared two-year blocks was 2.11–5.57. Zero and infinite resample ratios were retained. The relative change in occupied baits supplied about 87% of the log contrast; workers per occupied bait had a less clear change. The ratio was 1.86 on four plots without ant removal, and 2.47 when plots were pooled before calculation. The result shows a change in the relation between two survey indices. It does not estimate true colony density or identify a cause. It assumes complete surveys as described in the source methods; no separate empty-station ledger is available. The package preserves source files, hashes, code, all estimates, resamples, figures, and checks. A separate CSV program reproduced all 608 main count cells and the main estimate. A fresh run reproduced all 18 result and figure files exactly.

ants · Solenopsis · Portal Project · nest occurrence · bait surveys · long-term monitoring · paired change · reproducible ecology