Distribution of wintering Numenius arquata in Chang-hua coastline, Taiwan
Date Issued
2015
Date
2015
Author(s)
Lin, Chia-Chi
Abstract
Mudflat is the primary foraging habitat of wintering shorebirds. Shorebird distribution is related to mudflat type. The wintering population of Eurasian Curlew（Numenius arquata）shifted its distribution in the past 30 years in Chang-hua coastline. Curlew distribution change represents changes in their optimal habitat. In order to understand the cause of the distribution change, we must understand the preferred mudflat types for curlews. To do so, we observed wintering curlews’ distribution range on intertidal mudflat in Chang-hua coastline and studied the mudflat types in their distribution range. We found curlews mainly distribute themselves in Fang-yuan mudflat; furthermore, they seemed to prefer muddy substrates. Whilst there, their major behaviors included resting and feeding. To understand the substrate distribution of Chang-hua region, we collected 138 samples in the field and used Landsat satellite imagery to classify the mudflat type to ‘sand’ and’ mud’ through supervised classification. The overall accuracy of the classified map is 94%. Form the classified theme map, it was apparent that there were many muddy areas in Chang-hua coastline, but curlews, however, distributed themselves in particular muddy region of Fang-yuan. This suggested that there are others factors that affect curlews’ distribution on ’ muddy’ mudflats. We test whether if the distance to high tide roosting sites and human disturbances affect curlews’ distribution on ’muddy’ mudflat. Comparing between the ‘muddy’ mudflat areas with curlews and those without, we tested whether if the distances to (1) high tide roosting site and (2) wind turbines, (3) oyster culturing structure and (4) No. 61 West Coast Expressway were the factors in terms of curlew distribution. Our result revealed that curlews were distributed in ‘muddy’ regions near high tide roosting site. They were, on the other hand, distributed further away from wind turbines and No. 61 West Coast Expressway. 30 years earlier, none of the aforementioned infrastructures constructed. In hope to better understand curlews’ distribution change over the past 30 years, future studies must investigate (1) the change of ‘muddy’ mudflats and (2) the change in high tide roosting sites in north Chang-hua. Present study highlights the importance of mudflats on curlew conservation. While placing emphasis on the distance to feeding and roosting sites, it has come to light that various types of human disturbances may also play an important role in the distribution preference of the Eurasian Curlew.
Subjects
curlew distribution
mudflat type
satellite image classification
high tide roosting sites
human disturbances
Type
thesis
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