Adult male desert pocket mouse mass showed no clear response to the 2015 access change on 15 Portal plots in 2010–2019

We tested whether a change in kangaroo rat access was linked to mass within one smaller species at Portal, Arizona. Three plots changed to exclusion in 2015, three changed to full access, and nine kept the same access. We compared adult male desert pocket mice in 2010–2014 and 2016–2019, with 2015 omitted. The sample has 1,973 captures in 359 plot-quarter cells. A model with plot and calendar-quarter terms gave a mass contrast of +2.56% under exclusion, with a 95% plot-cluster interval from −0.63% to +5.85%. A null-restricted wild cluster test gave P = 0.1425. Thus the main test did not show a clear response. A separate 2021–2025 window also gave an interval that included zero. The two switch directions differed, and the groups changed before the gate change. A model that allows different trends gave much less precision. These results do not establish no effect or a cause. Gates can select animals by size, and sparse catches can change the sample. The package preserves source data, provenance, a local plan, all checks, figures, code, and repeat instructions. Independent CSV and matrix calculations reproduced the main results.

desert pocket mouse · competition · body mass · Portal Project · treatment change · open data · null result