Delaying conservation actions matters for species vulnerable to climate change

1. Climate change vulnerability assessments are commonly used to identify species or populations at risk from global climate change, but few translate impact assessments to climate change adaptation actions. Furthermore, most climate change adaptation efforts emphasize where to implement management actions, whereas timing remains largely overlooked. The rate of modern climate change introduces urgency in evaluating whether delaying conservation actions compromises their efficacy for reaching important conservation targets. 2. We evaluated the importance of multiple climate change adaptation strategies including timing of actions on preventing extinctions for a threatened climate-sensitive species, the Eastern Massasauga rattlesnake (Sistrurus catenatus). We parameterized a range-wide population viability analysis model that related demographic sensitivities to drought events and human-modified land cover to assess vulnerability to future climate change. Using simulations, we assessed the efficacy and trade-offs associated with alternative climate adaptation strategies aimed at maximizing the number of future populations including when to initiate conservation actions, duration of management, number of managed populations, and local management effectiveness. 3. Population-level projections under future climate change scenarios revealed a broad-scale pattern of range contraction in the southwestern portion of the current range. Along the extinction gradient, we identified demographic strongholds and refugia critical for population persistence under climate change as well as populations at high risk of extinction and candidates for climate change adaptation actions. 4. In the context of future climate change, the timing of conservation actions was crucial; acting earlier maximized chances of achieving conservation targets. Even considering uncertainty in climate change projections, delaying actions was less efficient and introduced undesirable trade-offs including the need to implement conservation actions for longer or targeting more populations to achieve a similar conservation target. 5. Synthesis and applications. Our findings highlight how acting quickly reduces risk and improves outcomes for a highly vulnerable species under future climate change. Climate change vulnerability assessments require translation of model-based outputs into tractable information for climate change adaptation planning. Quantifying trade-offs associated with the multidimensional decision space related to species conservation and recovery planning is a critical step in climate change adaptation.