Department of Physics, Chemistry and Biology (IFM)

The study was carried out in La Paz city (Bolivia) and their immediate rural surroundings, situated in an inter-Andean valley of the South American central Andes between 3.300 to 4.100 m over sea level. The climate is characterized by pronounced thermic variations throughout the day and digress according to the altitudinal gradient with no big thermic fluctuations throughout the year. There is a prolonged arid season (March-October) and a short humid season (November-February) (Lorini, 1991).

The vegetation cover is strongly altered. However, it is possible to observe differences in the flora composition depending on the altitudinal gradient, which defines three ecologic regions that influence the study area: “highandean region” (4.100/4.200-4.600-4.700 m), “puna region” (3.500/3.600 - 4.100/4.200 m) and “dry valley region” (2.900/3.000-3.400/3.500 m) (Beck & Garcia, 1991, Beck & Pinagua, 2010; López, 2010). The bird species composition also varies with altitude (Garitano-Zavala et al. 2010; Villegas & Garitano-Zavala 2010).