‘Unscrambling’ the drivers of egg production in Agassiz’s desert tortoise: climate and individual attributes predict reproductive output

The ‘bet hedging’ life history strategy of long-lived iteroparous species reduces short-term reproductive output to minimize the risk failure over a lifetime. For desert-dwelling ectotherms living in variable and unpredictable environments, is further influenced by precipitation temperature via effects on food availability limits activity. We assembled multiple (n = 12) data sets egg production for threatened Agassiz’s desert tortoise Gopherus agassizii across its range used these build range-wide predictive model annual as function weather variation individual-level attributes (body size prior-year status). Climate variables were more robust predictors than attributes, with overall positively related an earlier start spring activity season, negatively extremes (monthly March-April). Reproductive was highest individuals larger body sizes that reproduced previous year. Expected from 1990-2018 varied 2-5 6-12 eggs female -1 yr , weak decline expected this time (p 0.02). Climate-driven environmental highly correlated all 5 Recovery Units (Pearson’s r > 0.9). Overall, our suggests climate change could strongly impact tortoise, have negative population-level effect if significantly reduced species’ predicted under some models.