Bird assemblages in secondary forests developing after slash-and-burn agriculture in the Brazilian Amazon

Abstract

Although indigenous farmers and other traditional peoples have disturbed Amazonian forests for centuries, few studies investigate the effects of these disturbances on biodiversity. This short-term study investigates how bird assemblages are affected by agricultural practices adopted by the residents of a national park in the Brazilian Amazon. Twelve sites in secondary forest (four sites in three age categories) and 12 sites in primary forest were selected for bird sampling. Audio-visual censuses of birds were conducted in small plots (1 ha) of young secondary growth (4–5 y), middle-aged (7–15 y), and old (20–35 y) secondary forests. Each site in secondary forest had a corresponding control site in adjacent primary forest. Young secondary growth had fewer species than old secondary and primary forests. Bird species richness was similar in middle-aged, old secondary and primary forests. Bird communities of young secondary habitat were dominated by species normally found in open habitats, such as agricultural fields and igapó flooded forests. The bird species composition of young secondary growth was more similar to that of middle-aged forest, which in turn was more similar to that of old secondary forests. Bird species composition differed between young secondary growth and old secondary forests and primary forests and between middle-aged secondary and primary forests. Nectarivore/insectivores and frugivore/insectivores of monospecific flocks are significantly associated with secondary forests, especially in initial stages of forest regeneration. In contrast, specialized insectivorous birds that join mixed-flocks show a significant association with primary forest.

Forest structure in a mosaic of rainforest sites: The effect of fragmentation and recovery after clear cut

“…A large number of thin trees associated with a high density of individuals is very characteristic of the region's old-growth forests, a pattern which seems to be related to the occurrence of these forests on relatively nutrient-poor soils, in a climate with high rainfall evenly distributed throughout the year (Mori et al, 1983;Coomes and Grubb, 2000;Ter Steege et al, 2003;Martini et al, 2007). Although some groups of specialized animals may be limited in secondary forests, these sites provide adequate resources (food, nesting sites, and roosts) for many animal taxa (De Walt et al, 2003), including shelter (litter and fallen trunks) for ground herpetofauna (Garden et al, 2007) and small mammals (Garden et al, 2007), and food resources (lianas and pioneer species) for frugivorous birds (Borges, 2007).…”

Old growth and secondary forest site occupancy by nocturnal birds in a neotropical landscape

“…Barlow et al, 2007;Borges, 2007). All the SF bird studies that we are aware of, however, focus on diurnal birds.…”

Nestedness and Patch Size of Bamboo-Specialist Bird Communities in Southeastern Peru

“…Some of these, such as the Barred Antshrike (Thamnophilus doliatus), are widespread inhabitants of second growth and might be expected to occur in the bamboo die-offs, especially as the northern die-off is a mere 300 m from the nearest loop of the Manu River. Second growth supports many species characteristic of riverine successional vegetation, and such species are capable of dispersing into isolated patches of second growth (Terborgh and Weske 1969, Borges 2007). Furthermore, in 1984and 1985, a few riverine species, such as the Silver-beaked Tanager (Ramphocelus carbo), occurred in early-successional vegetation on a landslide in the plot, confirming their ability to disperse to the area.…”