Extinction risk modeling predicts range-wide differences of climate change impact on Karner blue butterfly

The Karner blue butterfly (Lycaeides melissa samuelis), an endangered species in decline due to multiple factors, including habitat loss, can be further threatened by climate change. Evaluating how climate shapes the population dynamics and distribution of the Karner blue (Kbb) is necessary for developing adaptive. Demographic models generally used for insect populations are often either density-dependent or applied to population presence-absence data in a density-independent manner. In contrast, we used scale-based, mixed density-dependent and density-independent (hereafter “endo-exogenous”) models for the Kbb, based on long-term count data of abundance during flight periods, to understand how different environmental variables, including climate, affected Kbb extinction risk through the middle of the 21st century. Our endo-exogenous models showed that density-dependent and environmental variables, including climate, topography, and tree canopy coverage, were essential drivers of Kbb population dynamics. We also found that Kbb’s response to climate differed between the species’ two annual generations and across its range: higher temperature and precipitation in summer generally benefited the second-generation populations, whereas there were uncertainties of the effects on the populations in different ecoregions during the first generation. These results imply that population-specific biotic/abiotic factors need to be incorporated into plans to manage the recovery of Kbb under climate change.