Sanctuary Mountain Maungatautari (SMM), New Zealand's largest pest‐fenced ecosanctuary, provides a unique opportunity to study invertebrate responses to mammal eradication. Beetles and wētā were monitored within the mouse‐free southern exclosure and in adjacent comparable forests on the mountain, within the predator‐proof fence (in 2004/05, then 2006/07 to 2012/13; n = 8 years), with methods and analyses repeated for monitoring in summer 2023/24 (1 year) and then compared across the 9 years. Data collected during 2004–2013 showed higher beetle species richness and abundance inside the southern exclosure in several earlier summers, with differences in patterns through time and among beetle size classes; the 2023/24 data revealed little difference between inside and outside. Beetle community composition changed following mammal eradication and then changed again with increasing mouse densities outside the southern exclosure. Wētā showed a stronger positive response, with consistently higher abundance inside the southern exclosure across multiple years and declines outside when mouse control ceased, supporting evidence that large Orthoptera benefit from mammal, particularly mouse, removal. Nineteen years after mammal eradication, invertebrate communities continue to show variable responses; these responses are influenced by both predation from recovering bird populations and persistent mice. The SMM dataset represents the longest‐running invertebrate monitoring in an ecosanctuary in New Zealand, providing critical insights into the long‐term impacts of pest mammal removal. Decadal resampling will be needed to track ongoing responses, with the next sampling scheduled for summer 2033/34.
Jo et al. (Thu,) studied this question.