Research

The dramatic decline of migratory landbirds has raised substantial conservation concerns. Yet most research and conservation efforts have been biased towards breeding and wintering ground, leaving the on-route migration understudied. I used the Next- Generation Weather Radar (NEXRAD) system to map the stopover hotspots and identified important habitats for migratory landbirds at the continental scale (Guo et al. 2023), while revealing that most hotspots are unprotected (Guo et al. 2024). To address this conservation gap, we are working with USDA-NRCS to incorporate the identified hotspots into the conservation frameworks under the Working Lands for Wildlife program.

An additional discovery stemming from my radar-based research highlights the potential role of the agricultural Midwest as a migration barrier. This is reflected by the large concentration of autumn migrants in the eastern forests right after crossing the "corn belt" (Guo et al. 2023). To compare how different species might negotiate the migration barrier in different ways, I am integrating eBird data with my fieldwork in southern Indiana to assess species-specific responses to this artificial migration barrier.

Climate change is driving global species redistributions. With global warming, montane species are moving towards mountain tops. Concurrently, habitat loss is also more severe in lowland regions. I conducted a meta-analysis of elevational species redistributions, and found that forest loss in warmer regions tend to accelerate species' upslope movement (Guo et al. 2018). Hence, the compounding effects between climate and land use change on species range shifts is likely to be higher especially in the tropics.

What determines global species distribution? For ectotherms like ants, the answer is usually temperature. The thermal tolerance of various ant species have been well measured under laboratory settings as the critical thermal maximum (CTmax) and critical thermal minimum (CTmin). However, in this meta-analysis, we found that foraging temperatures, measured in the field as the maximum and minimum surface temperatures for foraging activity, better predict global ant distributions than the lab-derived thermal limits (Guo et al. 2020).