ตปงท ปท 22 ฉบบท 1 .. 2558 Journal of Wildlife in Thailand Vol. 22 No. 1, 2015 DIFFERENCES ON TRILL SONGS OF STREAK-EARED BULBULS BETWEEEN UPPER AND LOWER OF NORTHERN IN THAILAND Natthaporn Liamjaidee 1 & Somboon Kamtaeja 2* ABSTRACT บทคด Vocal behaviours of many passerines changed rapid across geographical populations. This study aims to investigate acoustics differences on trill songs between geographic populations of Streak-eared Bulbuls, a locally resident frugivorous passerine of Thailand. Trill song were recorded from four populations including: 15 birds of Chiang Dao Wildlife Sanctuary, 6 birds of Chiang Mai University, 8 birds of Muang district, Phitsanulok province and 6 birds of Wachirabarami district, Phichit province. We compared four acoustic features of the trill songs. We found that frequency of maximum amplitudes and frequency bandwidths of trill songs were signiicantly different between two discrete geographical populations. Principal Component Analysis strongly predicted 96.40% of trill differences between the northern plateau populations and central plain populations. Therefore, population differences of bird songs could be shaped by discontinuous habitats which leading to limitation on population distribution and learning barrier between discrete geographic populations. Keywords: discontinuous habitat, geography, streak-eared bulbul, trill song กดงขงนกถปนปงดงก ปชกทนขตตทตกตงกน งน จนตถปงคทดบคตกตงขงงงงก ปชกขงนกปดน ซงปนนกปจ ถนขงปทท ดกบนทกงนกปดนจก 4 ก ปชก ดก ก ปชกนทขตกนธ ต ปชงด จนน 15 ต ก ปชกนททชง จนน 6 ต ก ปชกนทง จงด ณก จนน 8 ต ก ปชกนทชบ จงดจต จนน 6 ต ปบทบงคปกบ ขงงง 4 งคปกบ บคถกขงง ชงคถขงง งก ปชกท น นทบงขนทบคกงคตกตงงนคญทงถต Principal Component Analysis ธบคตกตงขงงง 96.40% งก ปชก ดงนนกณชตทตนงกน กดขง กกจตขงนกปดน ทกดคตกตงงงขงนก 1 คณทยตทคนย มทยยชภฏพบงคม 65000 2 คณคต มทยยชภฏชยงย 57100 * Corresponding author, E-mail: sbkamtaeja@gmail.com คตกตงขงงขงนกปดนงคนตนบนตนง ขงปทท ณฐ จด 1 บณ คตจ 2*