Vocalisations of tropical birds are still largely unexplored particularly the nocturnal species. This study examined and
quantitatively described the territorial calls and duets of the Sunda Scops-Owl (Otus lempiji), Brown Boobook (Ninox
scutulata) and Spotted Wood-Owl (Strix seloputo) based on 105 territorial call and four duetting recordings collected
from one forest reserve and oil palm smallholdings in Selangor, Peninsular Malaysia. Wilcoxon signed-rank tests found
significant differences (p<0.05) for almost all vocal parameters measured from the spectrograms derived from the duets
with one higher-pitched than the other. Being the first study to describe the vocal structure of the duetting calls of the
three Malaysian strigids, this study serves as a baseline for future behavioural study of nocturnal birds particularly
pertaining to conspecific interactions in the Sunda region.