Distribution modelling of the endangered spotted Greenshank (Tringa guttifer) in a key area within its winter range

摘要

The Spotted Greenshank ( Tringa guttifer ) is one of the most threated shorebird species in the world, but key environmental characteristics associated with its presence are still not well understood. Here we summarised historical records and recent survey results of wintering Spotted Greenshanks in Thailand, a country of particular importance for overwintering populations of the species, and constructed a species distribution model to examine four environmental variables associated with occupied sites in Thailand, including coastal type (rocky, sandy, muddy or mixed sandy beach), distance to estuary, distance to mangrove forest, and tide range, to identify suitable habitat for wintering Spotted Greenshanks. The results indicated that distance to estuary and coastal type had the largest effects suggesting that Spotted Greenshanks preferred muddy or mixed sandy coast and estuarine habitats. A few new potential areas were predicted along the coasts of Chantaburi-Trat, in the extreme eastern Thai Gulf, and Ranong and Phang Nga Provinces, on the Andaman Coast of Southern Thailand, which have not been previously surveyed for Spotted Greenshank. We suggest that rapid establishment of comprehensive surveys, especially boat surveys, in the predicted areas could help to discover previously unknown sites for wintering Spotted Greenshanks and assist our understanding of patterns of their habitat selection.