Data from: 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: (1) vaccination and (2) conservation translocation to re-establish a second population on neighboring 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 <5%, but risk doubled if population size declined and further increased with more frequent droughts. Translocation performed best if Santa Rosa Island had a large starting population size and habitat extent, and, more importantly, a low risk of WNV establishment; if Santa Rosa Island was inhospitable to WNV, quasi-extinction risk dropped to near zero. Main conclusions Translocation with targeted vaccination during high risk conditions was the most effective strategy to protect island scrub-jays from West Nile virus. Although vaccination often outperformed translocation, only scenarios that included a Santa Rosa population and vaccinations achieved acceptably low species-wide extinction risk across all potential future conditions. Our analysis informs strategies to improve the long-term viability of the most range-restricted bird species in the continental United States and provides a model for assessing conservation-translocation proposals for other species and threats.

入侵性病原体是日益严峻的保护难题，且常与气候变化、干旱、生境丧失等快速环境变化相伴发生。气候变化被认为助推了西尼罗河病毒（West Nile virus, WNV）的传播，该病毒可造成大规模禽鸟死亡。西尼罗河病毒被视为美国加利福尼亚州圣克鲁斯岛特有物种——岛屿灌丛鸦（Aphelocoma insularis）的主要威胁。
针对岛屿灌丛鸦的保护，学界已提出两种方案：(1) 疫苗接种；(2) 保护迁地（conservation translocation），即于邻近的圣罗莎岛重建第二种群，该方案假设圣罗莎岛的西尼罗河病毒感染风险更低。上述策略虽均在区域尺度开展，但彰显了全球层面的保护关切，对保护生物地理学（conservation biogeography）与气候适应研究具有战略意义。
研究区域：美国加利福尼亚海峡群岛
研究方法：本研究采用随机种群模型（stochastic population model），对比疫苗接种与迁地保护策略在最小化岛屿灌丛鸦25年准灭绝风险（quasi-extinction risk）方面的有效性。
研究结果：在当前无西尼罗河病毒的条件下，岛屿灌丛鸦的预测准灭绝风险极低（约0%）；但在模拟西尼罗河病毒暴发后，风险升至≥22%。为至少60只个体接种疫苗可将风险降至<5%，但若种群规模下降，风险会翻倍，且随干旱频次增加进一步升高。若圣罗莎岛初始种群规模较大、生境范围更广，且更关键的是西尼罗河病毒定植风险较低，则迁地保护策略效果更佳；若圣罗莎岛无法支持西尼罗河病毒定植，准灭绝风险可降至近乎为零。
主要结论：在高风险条件下配合针对性疫苗接种的迁地保护，是保护岛屿灌丛鸦免受西尼罗河病毒侵害的最有效策略。尽管疫苗接种往往优于迁地保护，但唯有同时包含圣罗莎岛种群与疫苗接种的情景，才能在所有潜在未来情景下将物种整体灭绝风险控制在可接受的低水平。本研究为提升美国本土范围内分布范围最狭窄的鸟类物种的长期生存能力提供了决策参考，同时也为评估其他物种面临其他威胁时的保护迁地提案提供了范式借鉴。