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Understanding how birds utilised songs and calls to communicate among conspecifics is crucial for their survival, yet it remains an understudied area in bird ecology. We studied the influence of perch height selection on the vocalisation of Pied Triller, a common garden bird, in two suburban landscapes namely Pustaka Negeri Sarawak Recreational Park, Kuching and Universiti Malaysia Sarawak campus, Kota Samarahan from October 2018 to February 2019. Using a Marantz recorder connected to a parabolic reflector, we recorded calls and songs during morning (0630-1030 hr) and late afternoon (1600-1830 hr). Perch object, tree species, roost substrate and perch height from the ground were identified and measured. Clear and good quality spectrograms were used directly to describe song and call types. Photos and video recordings were analysed to describe perch behaviour. The vocal output representatives were then matched to the corresponding behaviour displayed. Our results revealed that Pied Trillers emit four different vocal outputs namely (i) song type, (ii) call type A, (iii) call type B and (iv) call type C. A total of nine behaviours were observed, of which the perch-hop behaviour was observed the most from both male and female Pied Trillers (33.71%), followed by perching (29.21%), foraging (20.22%), preening (7.78%), defecating (2.25%), eating (2.25%), roosting (2.25%), bill wipe (1.12%) and flight (1.12%). They prefer to roost on high perch to emit calls compared to songs. This probably suggest that Pied Triller prioritised vocal transmission and signalling to avoid being masked by surrounding anthropogenic noises and to avoid being conspicuous to potential predators. The most frequently visited perch object was the Weeping fig tree, Ficus benjamina.   Keywords: Call, perch height, Pied Triller, song, suburban landscapes

Vocalization in birds serves an important role in territory establishment and mate attraction as well as maintaining conspecific interactions and providing signals pertaining to food or threat. In Malaysia, most raptor behavioral studies on vocalization have been carried out on nocturnal raptors. Such studies have often been limited by the difficulty of accessing habitats where forest species reside and by raptors' elusive behaviors. We assessed the vocalization and vocal activity patterns of a common diurnal raptor, the Changeable Hawk-Eagle (Nisaetus cirrhatus), in an isolated lowland forest reserve, the Ayer Hitam Forest Reserve in Selangor, Malaysia, in mid-April 2021. Automated bioacoustics recorders were placed for 5 d in four different sites to passively collect the hawk-eagles' vocalizations. We recorded 480 hr of calls over the 5 d and the Changeable Hawk-Eagle uttered at least seven call types, with peak and longer call events at midday (1100 H and 1200 H, respectively). Calls were heard from 30 min before sunrise (0600 H) until shortly after sunset (1900 H). Call type 1 was by far the most common call type (2738 calls over 5 d) and was uttered throughout the day, possibly during flight and when perched. Other call types were uttered from late morning (1000 H) with exception of call type 3, which was uttered earlier (0900 H). Our findings may help provide improved raptor survey methods as well as fill the knowledge gap for diurnal raptor vocalizations in Malaysia.

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