Decision analysis rooted in Indigenous and Western scientific knowledge identifies cost-effective strategies for managing hyperabundant deer to restore keystone places

The hyperabundance of herbivores—a result of altered human relationality
with the land and the extirpation of predators—is leading to large-scale
degradation of keystone ecosystems across the globe. Designing and
implementing socially acceptable and cost-effective strategies that
meaningfully reduce herbivore populations while allowing for the recovery
of ecological function and cultural relationality is an inherently complex
issue. As a result, decision paralysis is common, leading to delayed or
avoided action and continued ecosystem loss and degradation. Using a
structured decision-making process that incorporated expert elicitation,
population modeling, and cost-effectiveness analyses while honoring
multiple knowledge systems, we identified five discrete and four portfolio
strategies for managing hyperabundant black-tailed deer (Odocoileus
hemionus columbianus) in the Southern Gulf Islands of British Columbia,
Canada, with consideration to benefit, feasibility, and cost objectives.
Hunting led by local Indigenous Nations was ranked the most cost-effective
strategy when benefits were considered in terms of the well-being of
peoples and place holistically, and accounted for both Indigenous and
Western science worldviews. When only Western perspectives were included,
increased licensed hunting by local communities and hiring professional
deer reduction specialists were ranked the most cost-effective. However,
while increased licensed hunting had a >50% likelihood of project
uptake and success (i.e., feasibility), the strategy had <50%
likelihood of achieving any benefit objective. In comparison,
Indigenous-led hunting, professional deer reduction specialists, and all
portfolio strategies had >50% likelihood of meeting at least one
benefit objective, although only Indigenous-led hunting also had
>50% likelihood of achieving feasibility objectives. We
provide a roadmap for decision-makers across the globe to robustly and
transparently assess the problem of herbivore hyperabundance and inform
solutions within their context. Within the Salish Sea, our work highlights
the need to support hunting, and in particular, Indigenous-led hunting, as
cost-effective strategies to promote revitalization of wellbeing of
peoples and place.