Its numbers have dropped sharply over the past ten years, owing to a number of factors, such as the recent economic development of the island and the resulting gradual reduction of the original forest area, the influx of newcomers looking for work or to hunt, and the outright purchasing of the horned owls by Taiwan-based bird merchants.
角鴞在近十年急遽減少，除因蘭嶼逐漸開發、原始林面積日益縮小、外地人前去捕捉，加上台灣本島的鳥販來收購，也是蘭嶼角鴞銳減的原因。原本蘭嶼居民見到角鴞，就像我們見到烏鴉一樣，認為它是不吉祥的，不願多招惹。但因有鳥販購買，他們也開始抓角鴞。