Abstract: The onset of dawn chorus was studied for a period of fourteen months for bulbuls (Pycnonotidae) and house sparrows (Passer domesticus) in two different geographical locations. One is very quiet and semi lit place in the suburbs of the small Mediterranean city of Tulkarem/Palestinian Authority. The other location is comparatively noisy and very well lit place in the Ar-Rayyan urban district of the city of Riyadh/ Saudi Arabia where desert climate prevails. This study is the first of its kind and clearly shows that the timing of dawn chorus is similar for
autumn and winter seasons in both locations but major differences were observed from February until September between the two locations. It can be concluded that very early timing of dawn chorus during spring / summer for the Riyadh location cannot only be attributed to breeding season and is temperature dependent (strong positive correlation, r>0.6). The similarities for autumn and early winter between the two locations is very interesting in that it is not in agreement with the notion that big cities (urbanization) influence the timing of dawn chorus due to noise and light pollution. This emphasizes that dawn chorus is a complex process and that change in the onset and pattern of dawn chorus can not merely be attributed to one variable such as noise or light pollution alone.