The rise and rise of predator control: a panacea, or a distraction from conservation goals?

Abstract

We review the recent rise to prominence in Aotearoa New Zealand of predation-focused conservation management, critically assessing the likelihood that this will deliver outcomes consistent with national biodiversity goals. Using a review of literature describing the impacts and control of three groups of introduced mammals (wild ungulates, brushtail possums, and predators), we identify shifts in management emphasis over a century of conservation decision-making in Aotearoa. Predators are now a major focus and wild ungulates are left largely uncontrolled, despite increasing populations and evidence for their negative impacts on a wide range of indigenous species and ecosystems. This imbalance in management effort, which appears to be influenced increasingly by socio-political pressures, is much less likely to deliver outcomes consistent with Aotearoa's biodiversity goals than a systematic approach that addresses a full range of biodiversity threats. Overall, we interpret these shortcomings as reflecting long recognised issues with the governance and leadership of Aotearoa's biodiversity system. Changes are required to provide adequate, stable funding, improve clarity around goals, leadership, responsibilities and accountabilities, strengthen planning and prioritisation of management actions, and coordinate management among various conservation actors. We also argue for (1) a stronger role for ecological sciences through independent research aimed at strengthening the evidence base for management actions, and (2) explicit inclusion of science expertise in conservation policy development and management decision making. While recent extensive, landscape-scale predator control has caught the imagination of many and has undoubtedly delivered some gains for a small subset of indigenous species, it also risks creating a false sense of achievement that diverts attention away from other serious gaps in progress towards achieving national biodiversity goals. We make 12 recommendations to address these shortcomings.

Hunting of sika deer over six decades does not restore forest regeneration

“…Hunter organisations favour high deer numbers and sport hunter satisfaction. In New Zealand, hunter organisations have successfully opposed the reductions in sika deer populations required for successful forest regeneration (Leathwick & Byrom, 2023), making it difficult to rely on even unrestricted sport hunting as an effective forest management strategy. Following consensus that a deer population's impact on forests needs to be reduced, restrictions on hunting are often relaxed for sika and other deer species (Gerhardt et al., 2013; Kaji et al., 2010; Milner et al., 2006).…”

“…Given that the New Zealand flora is also poorly adapted to the impacts of browsing mammals (Lee et al., 2010), deer densities should be lowered as much as technically feasible. Such reductions can be achieved through commercial harvesting and government‐funded culling, which have been successful in restoring forest regeneration elsewhere in New Zealand (Leathwick & Byrom, 2023; Tanentzap et al., 2009). If sport hunting continues to be used to control sika deer in Kaweka F.P., ongoing failure of canopy replacement should be expected.…”

Asking the right questions about Predator Free New Zealand

“…Some of these, that were not noticed or corrected in time, have committed massive effort at national scale for little benefit to New Zealand's native ecosystems. A recent review raises the possibility that PF2050 might become one of them (Leathwick & Byrom 2023).…”

Small mice create big problems: Why Predator Free New Zealand should include house mice and other pest species

“…PF2050 funds large‐scale control and eradication trials, and development of potential new tools. However, PF2050 has been criticized for shortfalls in eradication technology, insufficient finance, low scalability of existing tools, and inadequate consideration of social and ecological complexity, each of which erodes viability of the initiative (King, 2023; Leathwick & Byrom, 2023; Linklater & Steer, 2018; Monks et al., 2023; Parkes et al., 2017; Peltzer et al., 2019). National biosecurity, that is, safeguarding from repeated international pest invasions, for example, has not been assessed despite being a prerequisite for eradication (Kennedy & Broome, 2019), and NZ's ability to manage pest reinvasions locally and regionally remains questionable (Barron et al., 2023).…”

“…Indeed, a major criticism of the PF2050 campaign to date is that desired outcomes for biodiversity have not been clearly articulated (Leathwick & Byrom, 2023;Innes et al, 2023). Given the known impacts of mice on NZ's native flora and fauna, their impacts on biodiversity loss globally, and their propensity for mesopredator release (see below), this is a major oversight and an opportunity missed.…”