AUTHORS: Benjamin Zuckerberg, University of Wisconsin-Madison; Jacy Bernath-Plaisted, University of Wisconsin-Madison; Christine Ribic, University of Wisconsin-Madison
ABSTRACT: Assessment of species' vulnerability to climate change has been limited by a mismatch between coarse macroclimate data and the fine scales at which species select habitat. Habitat is an important mediator of climate, and fine-scale habitat features may permit species to exploit favorable microclimates, but habitat preferences and life histories of species can also constrain their ability to do so. Few studies have examined how habitat selection and life history can interact to affect microclimatic exposure. We leveraged fine-resolution models of near-surface temperature and humidity in temperate grasslands to understand how microclimates affect climatic exposure and demographics in a declining grassland songbird community. We asked: 1) Do species select favorable nest-site microclimates? 2) Do habitat preferences limit the ability of species to access potentially favorable microclimates? 3) What are the demographic consequences of microclimatic exposure? We found limited evidence that grassland birds select beneficial cooler microclimates. Instead, many species appeared constrained by habitat preferences. While facultative generalists displayed flexibility to nest in denser vegetation that provided thermal buffering, most obligate species were associated with more exposed microclimates. Nesting success in facultative species was not well explained by microclimate variables, but success in specialized grassland obligates declined with elevated microclimate temperatures. These findings suggest that habitat specialists may be more vulnerable to future temperature extremes because of a limited ability to take advantage of favorable microclimates. More broadly, our work illustrates how microclimate and species life history can interact to influence the potential vulnerability of species to climate change.
