Microclimate mediates the strength and direction of avianbiotic interactions

Citation

Frey, S, Gerber, BD, Hadley, AS, Kim, H, Sutton, M, Ferrari, NC, and Betts, MG. Microclimate mediates the strength and direction of avian biotic interactions: a test of the stress-gradient hypothesis. Ecography. 2026; e08313. http://doi.org/10.1002/ecog.08313

Abstract

Theory predicts that the strength and direction of species interactions can shift frombeing competitive in benign environments toward being facilitative in stressful envi-ronments. However, the environmental context dependency of species interactions hasrarely been tested in animal communities. We capitalized on a 15-year, landscape-scaledataset, collected annually in a relatively stable old-growth forest environment, to testthe long-held hypothesis that the strength and direction of species interactions mightbe mediated by climatic conditions. It is generally accepted that competitive and facili-tative interactions drive the distributions of many species, but are rarely included inclimate envelope models, and may partly explain poor predictive performance of spe-cies distribution models in the face of climate change. Using multi-species dynamicoccupancy models applied to long-term data, we tested whether annual settlementby bird species could affect either the persistence or settlement by other phylogeneti-cally related species, and whether these interactions are mediated by microclimate. Wefound that species interactions were influenced by microclimate for a high proportionof species pairs (80%). Related species pairs more often showed settlement dynamicsthat were indicative of attraction rather than repulsion (55 versus 30%, respectively).In some cases, competitive interactions in colder microclimates flipped to becomefacilitative in warmer ones (15%) and vice versa (5%). Furthermore, species pairsthat were closely related were more likely to exhibit competitive relationships along atleast part of the microclimatic gradient. Our results highlight the importance of usinglong-term data to incorporate competitive and facilitative interactions into species dis-tribution models, and support the notion that the strength and direction of speciesinteractions can be dependent on microclimatic conditions.