Burrows buffer nest temperatures and offer a stable thermal microclimate for threatened seabird chicks during extreme events

Abstract

Abstract Climate change is altering the severity and intensity of extreme weather events. Occupying microhabitats that buffer extreme weather may help species avoid harsh environmental conditions. Monitoring important habitats during extreme weather can highlight species that may benefit from targeted conservation actions. We describe the thermal microclimate and buffering capacity of Atlantic puffin (Fratercula arctica) and Leach’s storm-petrel (Hydrobates leucorhous) burrows during extreme events and test for correlation between weather conditions and burrow characteristics on nest microclimate and buffering capacity. Both species’ burrows buffered temperatures during extreme cold weather as nests were 7.4–8.0°C warmer than external temperatures. In extreme warm weather, Leach’s storm-petrel and Atlantic puffin burrows were 9.5°C and 5.4°C cooler than outside temperatures, respectively. External temperature and wind speed were strong drivers of burrow temperature. Thus, the buffering capacity varied depending on the specific extreme events. Moreover, smaller burrow volume and greater canopy cover improved burrow buffering capacity during extreme events. Our results suggest that burrows may provide a direct line of defence for seabird chicks against cold and warming events. Given the complex responses of burrow microclimates to extreme events, quantifying how changes in environmental conditions will impact burrow-nesting seabirds in the future is key.