Urbanization alters the composition of biological communities and, therefore, ecological processes such as predation and destruction of bird nests. The identification of predator and destructor species is useful for designing research for the understanding of the effects of urbanization on these ecological processes. In this study, we identify the diurnal predator and destructor species of artificial bird nests in urban and peri-urban sites of the metropolitan region of La Paz, Bolivia, using webcams. The House Wren (Troglodytes aedon) was the only nest-destroying species, recorded in both urban and peri-urban environments. This species affected the nests by extracting material. Besides a predation event by the Andean Caracara (Phalcoboenus megalopterus) in a peri-urban site and one by the Domestic Cat (Felis silvestris catus) in an urban site, the species with the highest incidence of nest predation in both urban and peri-urban sites was the Chiguanco Thrush (Turdus chiguanco). A behavior that had not been previously reported for this species, and is very rare for the genus. In this report, we present two films of destruction events by the House Wren and two films of eggs predation events by the Chiguanco Thrush.

We used artificial bird nests baited with three commercial eggs of Common Quail (Coturnix coturnix). Nest were adapted from abandoned natural nests of local wild bird species such as the Rufous-collared Sparrow (Zonotrichia capensis) and Eared Dove (Zenaida auriculata). A battery of three nests was located during two periods of seven days each in six study sites in the metropolitan region of La Paz. Individual nests were separated between them between five to 16 m. The sites were three private urban gardens and three peri-urban private land. The two aforementioned periods correspond to the reproductive season of the birds (February 2012-May 2012 and September 2012-January 2013). We firmly attach each nest to the branches of trees or bushes at a height of 1.5-2.5 m above the ground. We monitored nests between 06:00 and 18:30 using Microsoft LifeCam HD-6000 720p HD webcams. Therefore, we recorded only daytime nest predators and nest destroyers. We installed the webcams at 30 cm from each nest, camouflaged inside a box covered with dry leaves. Each webcam was connected to the computer with a 10m USB cable. We obtained a continuous track per day using Spy v. 3.8.6.0. Software, in which we identified each event of nest predation or destruction plus the species involved.