Inferring the climate change response of hybridizing warblers that breed in North American temperate rainforests

Abstract

AbstractEfficient monitoring of the ecosystem response to climate change is crucial for conservation and restoration practices. Indicator species can serve as efficient tools for predicting the functional response of an ecosystem to climate change. Here I leverage the decades of citizen science data coupled with high-resolution spatiotemporal climate data to dissect the climate change response of hybridizingSetophagawarblers, indicator species of the temperate rainforest of North America. I found that breeding habitat temperature and precipitation significantly predicted the breeding occupancy of the northern species (S. townsendi)and especially strongly in the southern species (S. occidentalis). Both species showed positive climatic responses in the recent decade, when the recent breeding occupancy was greater than expected based on the historical contingency of occupancy-climate-coupling. This implies the potential climate adaptation or life history plasticity in the breeding warbler populations. However, the southern species (S. occidentalis) showed compromised climate response in 2000-10, when the predicted breeding occupancy was significantly lower than the expected contingency. I further evaluated the potential of breeding niche competition between the hybridizing warblers, reflected by their overlap of breeding occupancy. I found that the competition potential was the lowest in 2000-10 when both species were at the trough of breeding occupancy, which recovered in 2010-20. Future investigation of the physiological and behavioral mechanism underlying this climate change response could illuminate the effect of climate change on speciation and adaptation in the rainforest ecosystem.