Abstract

A study was carried out in the tropical forests of Silent Valley and Mukkali in the Western Ghats, Kerala from May 1988 to April 1993, to elucidate the seasonal changes of bird communities in the two vegetation types. Abundance and density of birds were assessed, using variable width line transects each month. The highest populations, 609-1, 892/square kilometer were found from December-April. Total number, monthly density and species richness of birds declined during monsoon. When compared, abundance and density of birds, observed in the evergreen forests was more (929/square kilometer) than in moist deciduous forests (747/square kilometer) . However, bird population showed more stability in the moist deciduous forests. Except for two summers, significantly higher bird density was obtained in the evergreen forests during summer (1, 074/square kilometer) . Bird species diversity was high during summer and low in monsoon in both the vegetation types. A direct negative