Multi-scale Habitat Selection By Two Declining East Asian Waterfowl Species At Their Core Spring Stopover Area

Animals respond to their environment at multiple spatial scales.Multi-scale analysis provides important theoretical insight into ecological patterns and processes,and facilitates effective conservation and management.Waterbirds were key bio-indicators for globally threatened wetland ecosystems but their multi-scale habitat selection mechanisms were rarely studied.We studied habitat selection of two declining waterfowl species,Greater White-fronted Goose(Anser Albifrons)and Tundra Bean Goose(A.serrirostris)at the core stopover area of East Asian waterbirds.Based on life-history traits and distribution of the two waterfowl species,we used dynamic Brownian Bridge Movement Model to conduct the research at three spatial scales: landscape(30,40,50 km),foraging(10,15,20 km)and roosting(1,3,5 km).We hypothesized that the landscape-scale habitat selection was mainly based on relatively coarse landscape metrics,while more detailed landscape features were taken into account for the foraging-and roosting-scale habitat selection.To test the hypothesis,we used the satellite tracking data and Maximum entropy(MaxEnt)model to investigate the habitat selection process at each scale.We found that:1.The optimal radii of Greater White-fronted Goose and Bean Goose are the same at the landscape,foraging and roosting scale,i.e.,40 km,20 km and 5 km.2.Coarse landscape features explain habitat selection at the landscape scale.Specifically,both waterfowl species preferred areas with a larger percentage cover of wetland and waterbodies.GWFG also prefer lowland,while Tundra Bean Goose TBG prefer an intermediate percentage cover(70%)of croplands.3.Detailed landscape features explain habitat selection at the foraging scale.Both species preferred aggregated waterbodies surrounded by scattered croplands.This finding supports the central-place foraging hypothesis which poses that the rate of habitat use declines as the distance from the roosting site increases.4.Detailed landscape features explain habitat selection at the roosting scale.Both species preferred well-connected wetlands,well-connected middle-sized waterbodies as roosting area.We thereby suggest a multi-scale habitat selection process during which waterfowl first target a region based on coarse landscape features,and then gather more detailed information to select foraging and roosting areas.Our finding could guide waterbird conservation practices and wetland management.Given the difficulty of increasing the percentage cover of waterbody and wetland at the landscape scale,we suggest that management actions should focus on improving local habitat quality by enhancing the aggregation and connectivity of waterbodies and wetlands,and develop less aggregated cropland in the surroundings.