• 作者： 張偉平; 任晃蓀
• 作者服務機構： 美國密蘇里大學生物系
• 中文摘要： 1.本實驗係利用具有三個伸延跑道的實驗平台（見圖1）從行為上測驗大灰褐色蝙蝠(Eptesicus fuscus)在背境干擾的狀況下對同時放置的一旋轉目標及一靜止目標的探測能力及選擇偏向。 2.在實驗中，當蝙蝠與放置目標的距離小於100厘米時，由任何一目標所反射回來的回音，其平均聲強均大於背境回音的聲強（圖2）。 3.目標物的旋轉係利用一電動馬達來達成，此電動馬達的躁音的頻率低於1千赫（圖3）。 4.在實驗時，蝙蝠探測兩個目標的總和均超過 90% 然蝙蝠選擇旋轉目標的次數卻高於其選擇靜止目標的次數（圖4）。 5.把在實驗中蝙蝠所發出的回音定位聲分析的結果顯示，蝙蝠由探尋目標的存在轉為爬向選擇的目標時，其回音定位聲信號的期間，與兩連續信號間的間隔均縮短，信號的頻率也下降（表1）。 6.本文試圖對實驗進行中的背境回音及躁音對蝙蝠回音定位行為的可能干擾加以討論，亦對蝙蝠較偏向於選擇旋轉的目標的現象，從動物的行為觀點加以解釋。
• 英文摘要： 1. Utilizing a three-ramp platform, we studied the detection of a revolving and a stationary target inthe presence of background clutter by trained Eptesicus fuscus (Fig. 1). 2. During the test, the meanamplitude of echo from either target was always larger than that of the background echoes at the bat-to-target distance of 30, 70 and 100 cm. The amplitude of the echo reflected back from a revolving targetwas modulated between a maximum and a minimum value. (Fig. 2). 3. An electric motor was used torevolve a target. The frequency contents of the motor noise were mostly below 1 kHz (Fig. 3). 4. Whilethe total percent response of approaching either target is always more than 90% at every bat-to-targetdistance tested, the bats approach a revolving target more frequently than a stationary one (Fig. 4). 5.Echolocation pulses emitted by the bats during the test were recorded and analyzed. The bats shortenedtheir pulse durations and interpulse intervals and lowered the frequency contents as they entered into thecrawling phase from the searching phase (Table 1). 6. Potential interference of background echoes andambient noise with the performance of the bats is discussed. The preference of a revolving target to astationary one by the bats is perhaps due to the fact that a revolving target has a higher releasing value thana stationary one does.
• 中文關鍵字： bat; echolocation; target; echo
• 英文關鍵字： --