Coulson, BiancaFreeman, Marc TrevorConradie, Shannon RoseMcKechnie, Andrew E.2025-10-302025-10-302025-06Coulson, B., Freeman, M.T., Conradie, S.R., McKechnie, A.E. (2025) Increases in humidity will intensify lethal hyperthermia risk for birds occupying humid lowlands. Conservation Physiology 13(1): coaf036; pp. 1-13, doi:10.1093/conphys/coaf036.2051-1434 (online)10.1093/conphys/coaf036http://hdl.handle.net/2263/105049DATA AVAILABILITY : The data collected in this study are available at https://data.mendeley.com/datasets/d8r9sz6yyz/1Please read abstract in the article. LAY SUMMARY Many tropical birds will experience hotter and more humid wet-season conditions in future. In an African forest frugivore, we found the maximum tolerable wet-bulb temperature is 31.7°C and risks of lethal hyperthermia will increase substantially by 2100. These findings reveal a pervasive but understudied threat facing birds inhabiting humid lowlands.en© 2025, © The Author(s) 2025. Published by Oxford University Press and the Society for Experimental Biology. This is an open access article distributed under the terms of the Creative Commons CC BY license.Body temperatureEvaporative coolingForestHeat tolerance limitTrumpeter hornbill (Bycanistes bucinator)HumidityThermoregulationArticle