Identification and conservation of critical nodes for shorebirds based on migration network perspective.

Background: The degradation and loss of critical nodes in the East Asian-Australasian Flyway (EAAF) migration network could have implications for the migration of shorebirds. The conservation of critical nodes along the EAAF is important for maintaining the stability of migratory networks. However, identifying these nodes remains a major challenge.

Methods: We used a network method that integrates GPS tracking data and remote sensing data to identify critical nodes for three shorebird species (Black-tailed Godwit (Limosa limosa), Eurasian Curlew (Numenius arquata), and Pied Avocet (Recurvirostra avosetta)) in migratory networks along the EAAF and priority conservation areas to facilitate the development of conservation and management plans.

Results: A total of 111, 37, and 81 nodes in the migratory networks were identified for the Black-tailed Godwit, Eurasian Curlew, and Pied Avocet, respectively; these included 25, 13, and 16 critical nodes, respectively. Node importance (node betweenness) was higher in the migration period than in the breeding and wintering periods. Habitat loss was observed in most stopover nodes. A total of 23 unprotected critical nodes were identified as priority conservation areas.

Conclusions: Habitat loss was observed in most of the unprotected critical nodes in stopover regions for all three species. The inclusion of these sites such as Haoyao sumu forest farm and Tianjin coast, into flyway site networks (the East Asian-Australasian Flyway Partnership (EAAFP)) should be prioritized, and the habitat quality of nearby alternative nodes should be improved. Future studies should focus on developing new node indexes that integrate ecological variables with each node's role in maintaining network connectivity using data from a larger number of tracked individuals and birdwatching data. Such studies could help identify currently unknown regions with critical habitats.