Abstract

For the study of the macroecology and conservation of Taiwan’s birds, there was an urgent need to develop distribution models of bird species whose distribution had never before been modeled. Therefore, we here model the distributions of 27 mostly rare and cryptic breeding bird species using a statistical approach which has been shown to be especially reliable for modeling species with a low sample size of presence localities, namely the maximum entropy (Maxent) modeling technique. For this purpose, we began with a dedicated attempt to collate as much high-quality distributional data as possible, assembling databases from several scientific reports, contacting individual data recorders and searching publicly accessible database, the internet and the available literature. This effort resulted in 2022 grid cells of 1 × 1 km size being associated with a presence record for one of the 27 species. These records and 10 pre-selected environmental variables were then used to model each species’ probability distribution which we show here with all grid cells below the lowest presence threshold being converted to zeros. We then in detail discuss the interpretation and applicability of these distributions, whereby we pay close attention to habitat requirements, the intactness and fragmentation of their habitat, the general detectability of the species and data reliability. This study is another one in an ongoing series of studies which highlight the usefulness of using large electronic databases and modern analytical methods to help with the monitoring and assessment of Taiwan’s bird species.

中文摘要

為了由巨觀生態學的角度增進對臺灣鳥類的瞭解，並提供保育資訊，建構未曾被研 究過之物種的分布預測模式為當務之急。本研究以在樣本數偏低時仍被認為能產生可信賴 預測結果之最大熵（maximum entropy, maxent）模式方法建構27種稀有或隱蔽性繁殖鳥類 之分布預測模式。我們整合生物分布調查研究報告、逐一聯絡中華鳥會資料庫中的稀有種 紀錄者、搜尋網路公開資料庫以及文獻報告，建構高品質的物種分布資料庫，得到本研究 27個目標物種的「出現紀錄」資料共涵蓋2022個1 × 1 公里網格；將此資料與預先篩選的 10個環境因子建構各物種的分布預測機率模式，並以「最小出現機率值」（lowest presence threshold）為閾值，保留大於閾值的分布預測機率值，但將小於閾值的分布預測機率值轉 換為零，作為預測結果。我們逐一探討各物種的分布預測結果，如棲地需求、棲地完整性 或破碎化程度、物種偵測度，以及資料可信度，並提出應用建議。本研究屬於利用大尺度 電子資料庫與近代分析技術協助臺灣鳥類監測與評估系列研究之一。

Keyword: Biogeography, conservation status, GIS, rarity, Taiwan avifauna.