DISTRIBUTION OF BIRDS ON EASTERN AND WESTERN SLOPES OF THE SIERRA ACONQUIJA IN THE NORTHWESTERN ARGENTINE ANDES

The populations of birds (diurnal birds of prey excluded) were studied on both east and west oriented slopes in the Sierra de Aconquija, Tuc uman province, northwestern Argentina. The transect method of bird obs ervation was combined with strip surveys. The study period was mid Nov ember till early March, during which time most of the Andean bird spec ies are breeding. The eastern slope has frequent fog, whereas the west ern one is sunny with scarcely rain. Species occurrence and abundance were recorded which in part depend on the altitude. Probable further r easons for these patterns of local distribution are discussed.