Efficacy testing of Goodnature A24 self-resetting rat traps for wild house mice (Mus musculus).

House mice (Mus musculus) are worldwide pests in urban, agricultural, and natural settings. Goodnature® A24 rat+stoat self-resetting traps (A24s) are used globally for invasive rat control, yet adequate efficacy testing has not occurred against house mice. Our objective was to test efficacy of A24s against wild house mice. We first used cage/pen trials to determine whether the time from A24 impact to death was short and met international animal welfare standards (New Zealand National Animal Welfare Advisory Committee [NAWAC]). We varied lure type (peanut butter vs. Goodnature chocolate lure) and trap configuration (vertical vs. angled in a trap stand) to assess trap attractiveness. Of the 80 mice tested, 67 triggered A24s, and just three required our intervention and euthanasia because they were still alive 2 minutes after being struck by the A24. Time to death for the remaining 64 mice averaged (± SE) 50.9 ± 2.6 seconds (median: 46.8 seconds, range: 19.8–120 seconds). Thus, A24s passed NAWAC standards of Class B for kill-traps against house mice. Although mice frequently contacted A24s during the 3-day trials, average time to trigger was 4.6 ± 0.6 hours and 13 mice never triggered A24s. Baiting A24s with peanut butter resulted in significantly greater mortality (98%) than by using Goodnature chocolate lure (70%). Mice triggered A24s baited with peanut butter 2.3 times faster than Goodnature chocolate lure, and 2.7 times faster if A24s were angled in trap stands rather than positioned vertically. In further trials, we released groups of up to five mice into a 24 m2 arena containing either two A24s or two snap-traps+two A24s. Two A24s in the arena resulted in all 25 mice triggering A24s and dying; mice were undeterred from triggering A24s when mouse carcasses were near A24s. When snap-traps and A24s were present, one of 38 mice survived the 9-day trials. If snap-traps were reset each 24 hours they killed significantly more mice than A24s, yet if they were not reset during trials the A24s killed significantly more mice than snap-traps. A24s appear adequate for use against house mice, especially if baited with peanut butter and angled in trap stands. [ABSTRACT FROM AUTHOR]