FOSSIL-AUGMENTED SPECIES DISTRIBUTION MODELS REVEAL SHIFTING BASELINES FROM THE PLEISTOCENE TO THE PRESENT FOR THE CALIFORNIA CONDOR

Climate change threatens to alter the present and future distribution of numerous species globally. While predicting distributional changes is critical in guiding management efforts, recent advances in conservation paleobiology have shown that the present-day relationship between species occurrences and bioclimatic variables may be biased by prehistoric and historic anthropogenic influences; therefore, using solely present-day data can result in incorrect assessments of the species’ climatic envelopes.

Late Pleistocene and Holocene fossil records have emerged as important archives of past responses to climate change. We investigated the utility of fossil data in producing more accurate long-term forecasts for an endangered species occupying both historical and novel ecosystems, the California condor (Gymnogyps californicus). We leveraged the rich Quaternary record available from California including Rancho La Brea and other deposits, in combination with modern observations from citizen science platforms such as eBird. We used occurrences from localities dated to the Last Glacial Maximum to make predictions for ranges under present-day climatic scenarios as a conservation counterfactual, and compared this counterfactual with the actual present-day distributions, quantifying the effects of shifting baselines.

We found that Pleistocene model predicted current condor presence in Big Sur and Southern California to a high degree of accuracy. The model was then used to identify and map potential future areas of colonization and extinction and detect areas of habitat fragmentation. We highlight opportunities for interdisciplinary collaboration and advocate for the integration of fossil datasets from the Pleistocene to meet conservation challenges of the Anthropocene.