何處惹窗殺？台北文湖線捷運站鳩鴿鳥擊之地景特徵與空間分布

Abstract

「窗殺」為撞擊玻璃引起的鳥類傷亡，是野鳥主要的非自然死亡原因之一。現今，高架捷運站常採用開放空間與大面積玻璃的設計，但這些設計可能與周遭的地景特徵交互作用，進而產生潛在的窗殺風險。此外，台灣常見鳩鴿科鳥類窗殺案例數多，且易在玻璃上留下痕跡，是適合在清掃效率高的公共場所觀察窗殺風險的鳥種。因此本研究定期於台北市文湖線上的16個高架捷運站進行鳩鴿撞玻璃調查，探討站體特徵、地景組成因子、地景結構因子與周遭鳩鴿科族群數量如何影響鳩鴿科撞玻璃風險，並比較8組高、低窗殺風險玻璃中的窗景，分析窗景組成差異對鳩鴿科撞玻璃風險之影響。研究於2022年4月至隔年5月共記錄到143筆鳩鴿科撞玻璃證據，多數案例分布於月台兩端玻璃牆和空橋等玻璃透明度較高的區域。地景方面，100公尺環域內之建物、不透水層鋪面比例與附近鳩鴿科族群數量為影響鳩鴿科撞玻璃風險之關鍵因子。距玻璃近的建物透過減少玻璃視覺延伸效果與限縮玻璃前方可活動空間，可降低鳩鴿科撞玻璃風險，而玻璃附近較空曠且附近鳩鴿科族群多，可能因玻璃視覺延伸度高加上鳩鴿活動量大，導致撞玻璃風險提升。另外，綠地相關變數對鳩鴿科撞玻璃風險的影響不明顯，與北美窗殺研究結果相反，這可能與常見鳩鴿科普遍適應都市化環境而對植被依賴度較低有關。窗景方面，玻璃中樹冠畫面比例增加會吸引鳩鴿科鳥類，提升該面玻璃的鳩鴿科撞玻璃風險，建物畫面增加則可能減少撞玻璃風險。根據研究結果建議，高架捷運站可針對玻璃面積大、周遭空曠，鳥類數量多且有樹冠畫面的玻璃，以窗貼空白處不超過5×10公分原則優先進行窗殺減緩措施。在新站設計上若無法避免使用玻璃，除了盡量減少玻璃面積外，減少玻璃前方空間，避免玻璃畫面出現植被、樹冠或空曠地景也能降低窗殺風險。

"Bird window collision (BWC)" refers to an unnatural bird death caused by striking the glass of artificial structures, which is one of the main causes of unnatural bird mortality in the world. Nowadays, elevated MRT stations are usually designed with open spaces and large glass, but these designs might interact with the landscape and cause potential BWC risks. Additionally, the common Columbidae birds are recorded to have large number of BWC cases in Taiwan, and they are easy to leave with the evidence on the glass after striking, which make them become the birds that are suitable for observing BWC risks in the public places with high cleaning efficiency. This study investigated 16 elevated MRT stations of Wenhu line in Taipei to collect the BWC evidence from Columbidae birds, and to explore how station features, landscape composition/ configuration factors, and local Columbidae bird population affecting the risk of Columbidae BWC. Also, this study analyzed the impact on Columbidae BWCs from different window view compositions by comparing 8 sets of high/low BWC risk window views. A total of 143 Columbidae BWC cases were recorded from April, 2022 to May, 2023, and most cases were distributed at glass walls and sky bridges where the reflection or the transparency of the glass is high. In respect of the landscape, the building area ratio and the impervious area ratio in 100 m buffer zones and the nearby Columbidae population size are the key factors affect the Columbidae BWC risks in MRT stations. The presence of buildings near the MRT glass can decrease BWC risks through reducing the visual effect of extensibility and the bird active space in front of the glass, while the larger Columbidae population and the open landscape showing in the glass of MRT stations may lead to the increasing of the BWC risks because of the high visual effect of extensibility and the active Columbidae populations. In addition, vegetation-related variables show no significant effect on the BWC risks, which is contrary to the results from most studies from North America, this might be due to the good adaptation ability of most Columbidae birds toward the urbanized environment that makes them have less dependence on vegetation. In the respect of the window view, this study shows that the increase in canopy area ratio in the window view will attract Columbidae birds and raise the BWC risks. On the contrary, the increase in the building area ratio might decrease the risks. We suggest that the large station glass which is near the open landscape, large Columbidae populations, and large area of canopy view should be concerned with the BWC prevention measures in priority, with window sticker rule that the blank area shouldn’t exceed 5×10 cm2. For the newly designed stations, in addition to reducing the glass area, restricting the space in front of the glass and avoiding the vegetation and open landscape view showing in the windows can also help mitigate the BWC risks.