Abstract: The diurnal variation of physiological rhythm is an important adaptation mechanism of animals to the environment. In order to understand the diurnal variation of the physiological rhythm of Chinese bulbul (Pycnonotus sinensis), the adult Chinese bulbuls in Wenzhou of Zhejiang Province were live-trapped by mist net in June 2008, and their diurnal body temperature (T_b), body mass (M_b), and basal metabolic rate (BMR) were measured by inserting a digital thermometer (Beijing Normal University Instruments Co., model TH-212) into cloaca, weighed with a Mettler-Toledo balance (model PL3001-S), and determined with a closed circuit respirometer at controlled temperature (±0.5 ℃), respectively. The T_b and M_b of the adult Chinese bulbuls had  obvious diurnal variation, being significantly lower at 4:00 than at 18:00, but the amplitude of variation was remarkably higher at night time than at day time. The BMR was significantly lower at night time than at day time. The diurnal variation of the rhythms of T_b, M_b, and energy metabolism reflected an inner physiological energetic balance of Chinese bulbul, and played important roles in the diurnal acclimatization of the bird.

Key words: SOM dynamics, SOM model, Diffusion motion, Translation motion, Terrestrial ecosystem