Department of Physics, Chemistry and Biology (IFM)

Chiguanco Trush (Turdus chiguanco) was the species selected for this study. It is a passeriform of around 27 cm and 107 g, plain olive grey-brown and slightly paler below, yellow bills and legs (sexes are similar) (Figure 1). It is a sedentary bird distributed from Ecuador to Argentina, including Peru, Chile and the west and South of Bolivia (Ribera, 1991; Collar, 2005). Its natural habitat are agricultural and semi-open areas, hedges, gardens, parks, deciduous woodlands, mainly in arid regions but usually near water flows, also in bushy areas of the puna region, polylepis woodland and montane scrub (Collar, 2005). It has conquered a wide variety of habitats from 2800 m to 4300 m above sea level (Ribera, 1991). In the city of La Paz is one of the most commonly spotted birds, founded both in the rural areas and in the most anthropized urban places of the city. (Ribera, 1991). It has been defined as a generalist species that can feed in earthworms, insects, spiders, fruits of agricultural fields, berries (Collar, 2005), seeds, mice, lizards, eggs, frogs, and even chicklets of other species (Ribera, 1991). It can be found both solitary or in groups (Ribera, 1991). In Bolivia the reproductive season starts in December and eggs and fledglings are observable between January and April (Fjeldså & Krabbe 1990; Collar, 2005).