Biogeographic Modeling of Migratory Shorebirds

Abstract

Migratory shorebirds (Order Charadriiformes: families Scolopacidae, Charadriidae, Recurvirostridae) undertake among the longest animal migrations on Earth, traversing multiple biogeographic regions and depending on a chain of staging sites whose spatial configuration and habitat quality collectively determine flyway-scale population dynamics. This study applied ensemble biogeographic models (MaxEnt, Random Forest, BRT) to characterise present and future (2050, 2070 under SSP2-4.5 and SSP5-8.5) climatically suitable stopover habitat for ten shorebird species spanning the East Atlantic, Central Asian, and East Asian-Australasian flyways, integrating GPS telemetry data from 284 tracked individuals to validate model predictions against observed stopover site use. Ensemble models showed strong performance (mean AUC = 0.89 +- 0.04; TSS = 0.74 +- 0.05). GPS telemetry confirmed model-predicted high-suitability areas as actual stopover sites for 84.2% of tracked individuals. Under SSP5-8.5 by 2070, all ten species projected net losses in climatically suitable stopover habitat averaging 32.6 +- 8.4%, with the most severe losses in Arctic breeding habitat (-48.2 +- 9.6%) and intertidal staging sites in tropical latitudes. Connectivity analysis across the three flyways identified 18 critical bottleneck sites whose loss would disconnect >= 30% of the modelled flyway network for >= 3 species simultaneously. These bottleneck sites, predominantly in the Yellow Sea, East African Rift Valley lakes, and northwestern European estuaries, represent the highest conservation priority for shorebird population persistence under projected climate and land-use change. These results directly inform Ramsar Convention site prioritisation and East Asian-Australasian Flyway Partnership conservation planning.