宜蘭縣無尾港地區小水鴨度冬棲地特性

Abstract

宜蘭縣無尾港水鳥保護區為臺灣本島第一個水鳥保護區，每年冬季皆有大量水鳥來此過境、停棲，其中為數最多者為來自亞洲北方的小水鴨。由於無尾港地區冬季水田常為休耕、蓄水狀態，故來此度冬的小水鴨除了棲息於保護區內水域外亦廣泛分布於無尾港地區水田區域，水田環境含有無脊椎動物及有機質，為小水鴨覓食的絕佳場所。然近幾年來無尾港地區觀察到的小水鴨逐漸減少，無尾港地區的水田環境也在變化中，為保護小水鴨之棲息環境，首要釐清小水鴨喜好之棲地條件，並推估其潛在之分布位置。本研究以小水鴨為研究對象，針對小水鴨出現位置做環境因子調查，並進行無尾港地區小水鴨度冬棲地適合度研究，嘗試找出小水鴨偏好之確切環境條件數值及適合其棲息之環境。本研究結果顯示小水鴨偏好水深小於10 cm 之水域環境，尤以0 cm 至5 cm 最佳；植被方面小水鴨雖偏好周邊有植被生長之空曠水域；水域面積方面小水鴨多分布於面積5000 m2以內之棲地，連續水域面積大小則無此限制；與人為建物或道路之距離以37 m 以上為佳，與植被距離則偏好13 m 以內。本研究嘗試建立小水鴨度冬棲地適合度指標模式的結果相關性雖不高，但初步嘗試結果仍可提供無尾港水鳥保護區經營管理上的建議。

Yilan country Wuwei Harbor Waterbird Refuge is the first migratory waterbird refuge in Taiwan. Every winter, lots of waterbirds come here for resting or foraging, and the amount of the green-winged teal (Anas crecca) is the highest one. Green-winged teals appear not only in the protected area, but also in the fields out of the protected area, because of the fields in Wuwei Kong area are filled with water and invertebrates in winter. However, the amount of green-winged teal is decreasing over the years. In order to protect the habitats of green-winged teal, the first step is to figure out the preference of the green-winged teal when choosing habitats, and then study its spatial distribution model. This study use two methods to construct the spatial distribution model of green-winged teal, one is the land use types, the other one is the environmental factories. The result have shown that the green-winged teal prefer the land ues type of forest, fallow fields and the area near the fields. In aspect of the environmental factories, green-winged teal prefer the area with the depth between 5~15 cm, and surround by vegetation which height lower than 10cm or higher than 30cm. The water surface it prefer is about 3500cm2.