An assessment of lethal trap performance and efficacy at Haleakala National Park

Abstract

Control of non-native predators is vital for managing resources at Haleakalā National Park and has been ongoing since the 1970s. A 2016 evaluation of the trapping program suggested incorporating lethal traps to improve capturing predators. A revised Predator Control Management Plan was developed based on this evaluation, including lethal traps. Since lethal traps can catch non-target species, including federally listed threatened and endangered species, evaluating these traps was necessary. This project assessed three lethal traps for performance and efficacy: Goodnature® A24, DOC 250, and Belisle 220 Super X body grip traps.

We evaluated the use of exclusionary box designs and careful trap placement to determine if these features would prevent the capture of non-target species. Captures of species for each trap and interactions of target and non-target species with traps were examined to evaluate trap and exclusion device performance. Wildlife cameras paired with all lethal traps showed no interactions or “unacceptable” interactions with traps or trap boxes by native species, including federally listed species.

Capture rates from lethal and live traps were compared in similar areas. Of captures from Goodnature traps, 99% were rats, and 1% were mongooses. Of DOC 250 captures, 71% were mongooses, 25% were rats, and 4% were cats. Body grip traps did not capture any animals during the evaluation period but captured one mongoose during the efficacy period. Goodnature traps had the highest capture rate for rats, followed by DOC 250 and cage traps. DOC 250 had the highest capture rates for mongooses, followed by cage traps.

Staff noted that although lethal traps require considerable labor for initial setup, lethal traps required much less labor to monitor than live traps and were advantageous in remote areas. This study suggests that incorporating lethal traps could greatly benefit the predator control program at Haleakalā National Park.