The effects of temperature extremes on survival in two semi‐arid Australian bird communities over three decades, with predictions to 2104

Abstract

AbstractAimOrganisms in arid and semi‐arid regions are frequently exposed to climatic extremes and accordingly among the most vulnerable to climate change. Studies of seasonal differences in vital rates, which mediate effects of climate on viability, are rare in arid species, limiting ability to project population trends. We quantified survival patterns for two bird communities as a function of exposure to temperature extremes in winter and summer, then projected survival patterns to 2104.LocationSemi‐arid eastern Australia.Time period1986–2016; 1986–2104.Major taxa studiedBirds.MethodsUsing mark–recapture time‐dependent Cormack–Jolly–Seber models and data for 37 species from two >30‐year ringing programmes, we tested for effects on 6‐monthly survival of exposure to temperatures >38 and <0°C. We then predicted future survival for different emission scenarios, testing whether changes in survival associated with warming winters would be sufficient to offset the effects of rising summer temperatures.ResultsSurvival probability declined strongly with increasing exposure to days >38°C and to a lesser extent to days <0°C, with temperature extremes explaining 43 and 13% of temporal variation in survival among years, respectively. Summer survival patterns were similar across avian guilds but only survival of nectarivores declined in winter. Our models predict that gains in winter survival will not offset reductions in summer survival. Annual survival is predicted to decline substantially by the end of the century: from .63 in 1986 to .43 in 2104 under an optimistic emission scenario and to .11 under a pessimistic scenario.Main conclusionsWe highlight the significance of temperature extremes for species' persistence in arid and semi‐arid regions, comprising 70% of Australia's landmass, and 40% globally. Our demography‐based results are consistent with physiological‐based projections evaluating avian survival in arid and semi‐arid regions globally and suggest rising summer temperatures pose a risk to population persistence in these regions.