Studentised (unit-weight error) residuals as a function of trail position for all three-trap species calibrations. Upper panel: blue variant (AF+BP) devices. Lower panel: red variant (RP) devices. The thick dashed lines indicate the 16%, 50%, and 84% (red, black, and red) quantiles, which correspond to the distribution median ±1σ. The thin red lines show the ±1 expected position assuming normally distributed uncertainties.