Translocation with targeted vaccination is the most effective strategy to protect an island endemic bird threatened by West Nile virus

Aim Invasive pathogens are a growing conservation challenge and often occur in tandem with rapid environmental transformation, such as climate change, drought and habitat loss. Climate change appears to have facilitated the spread of West Nile virus (WNV), a cause of widespread avian mortality. WNV is considered the primary threat to island scrub‐jays (Aphelocoma insularis), endemic to Santa Cruz Island, California. Two approaches have been proposed to safeguard island scrub‐jays: (a) vaccination and (b) conservation translocation to re‐establish a second population on neighbouring Santa Rosa Island, hypothesized to have a lower risk of WNV. These alternatives operate at regional scales but exemplify global concerns with strategic implications for conservation biogeography and climate adaptation. Location California Channel Islands, USA. Methods We compared the efficacy of vaccination and translocation strategies at minimizing 25‐year quasi‐extinction risk for island scrub‐jays using a stochastic population model. Results Under current WNV‐free conditions, the predicted quasi‐extinction risk for island scrub‐jays was low (~0%) but increased to ≥22% with simulated WNV outbreaks. Vaccinating ≥60 individuals reduced risk to