Forest birds in landscape mosaics: Theory and empirical evidence

Most theories used in the study of the effects of ecosystem fragmentation assume that communities and populations live in discrete patches of habitat surrounded by a completely useless (non-habitat) matrix. However, most fragmented landscapes do not conform to patch-matrix models and are more adequately defined as a mosaic of patches of different attributes.; I analyzed the population dynamics of birds living in patchy environments from a landscape mosaic perspective, where all patches are described in terms of the abundance of some of the key resources on which birds depend.; Using an individual-based simulation model I studied the effect of the relative location of food and nest sites on the relationship between breeding-habitat patch size and bird population density. I observed that when both variables co-occur inside the breeding habitat patches, larger patches tend to sustain higher population densities whereas in cases where some foraging resources are present in the matrix the trend reverses. The results underscore the importance of the management of the matrix on the conservation of bird populations in fragmented landscapes.; In a fragmented forest landscape dominated by pine plantations in the Maule Region of Central Chile I studied the effect of the relative location of food resources and nest sites on the distribution of six insectivorous bird species. During the breeding season most birds were positively associated with the abundance of nest sites and for some species the best predictor of their abundance was the product of the density of food and nest sites. During the non-breeding season however most birds did not show significant spatial association with the studied resources.; Finally I studied the effect of the concentration of native vegetation around the nest on breeding success of the Thorn-tailed Rayadito, a cavity-nesting insectivore. I observed that the species' nest success was inversely associated with the amount of native vegetation, probably due to higher concentration of predators and competitor in native forests.