Avian assemblages in bamboo and non-bamboo habitats in a tropical rainforest Débora Cristina Rother A , Kaizer José Ferreira Alves B and Marco Aurélio Pizo C,D A UNESP – Universidade Estadual Paulista, Departamento de Botânica, 13506-900 Rio Claro, São Paulo, Brazil. B Instituto Adolfo Lutz – Regional de Rio Claro, 13500-090 Rio Claro, São Paulo, Brazil. C UNESP – Universidade Estadual Paulista, Departamento de Zoologia, 13506-900 Rio Claro, São Paulo, Brazil. D Corresponding author. Email: pizo@rc.unesp.br Abstract. Some species of bird are closely associated with bamboos (bamboo specialists) but community-wide studies comparing the avian assemblages in bamboo and non-bamboo habitats are lacking. Using point counts, we compared the species richness, abundance and composition of the avian assemblages in bamboo and non-bamboo habitats in the Brazilian Atlantic forest. Apart from considering bamboo specialists and non-specialist species, we contrasted birds from different categories of forest dependence, forest strata and diet. We recorded a total of 81 species of birds (74 in bamboo, 55 in non- bamboo habitats), including 15 bamboo specialists. Species richness was greater in bamboo habitats in all categories of diet and forest dependence. Bamboo and non-bamboo habitats had a similar number of canopy species, but bamboo habitats had a greater number of non-canopy species. The abundance of the whole avian community or of each of the dietary categories did not differ between habitats. The overall species composition differed between habitats, with a more homogeneous composition in non-bamboo habitats. A great number of species use bamboo habitats, even if they are not bamboo specialists. The initial expansion of bamboos, forming discrete patches of bamboo within mature forest, represents an intermediate-level disturbance that enhances forest heterogeneity and promotes the diversity of avian communities. Additional keywords: Atlantic forest, Brazil, diet, forest dependence, forest strata, intermediate-disturbance hypotheses. Received 28 February 2012, accepted 26 September 2012, published online 3 January 2013 Introduction Bamboos form distinct microhabitats in forests around the world (Stotz et al. 1996; Judziewicz et al. 1999). The particular archi- tecture and growth form of bamboos can profoundly change the local vegetation structure, alter forest dynamics and regeneration and reduce the diversity of plant species (Oliveira-Filho et al. 1994; Guilherme et al. 2004; Fantini and Guries 2007). The massive seed production of bamboos and colonisation by veg- etative reproduction are characteristics that allow bamboos to become dominant in forests, forming distinct and sometimes extensive patches. In south-western Amazonia, for example, ~180 000 km 2 of forest are dominated by the bamboos Guadua weberbaueri and G. sarcocarpa (Nelson 1994; Griscom and Ashton 2003). Despite their effect on forest structure and function, bamboos provide foraging opportunities for insectivorous and granivorous birds, some of which are closely associated with bamboos and are considered bamboo specialists. Insectivores may find a variety of prey items in suspended dead leaves, in cavities in bamboos and along the culms and foliage of bamboos (Kratter 1997; Díaz et al. 2005). Granivores profit from the massive production of seeds that characterise bamboo reproduction (Janzen 1976), typically tracking bamboo reproductive episodes (Areta et al. 2009). For the lowland and montane Atlantic forests of the Neotropical region, Stotz et al.(1996) respectively listed 19 and 24 bird species typical of bamboo-dominated microhabitats, but other species of these forests may also be considered bamboo specia- lists (Bodrati et al. 2010; Santana and Anjos 2010). In the Amazonian region, 18 of 474 bird species recorded in Alta Floresta, Brazil, were confined to bamboo patches (Zimmer et al. 1997), and at the Tambopata Reserve, Peru, 25 bird species were confined to forest patches dominated by the giant bamboo G. weberbaueri (Kratter 1997). In the Tambopata Reserve, bamboo-dependent birds were a significant part (6%) of the total bird community (Kratter 1997). To date, studies of the relationship of birds with bamboos have focussed on subsets of the avian community, especially under- storey insectivores and granivores (Reid et al. 2004; Santana and Anjos 2010). Frugivores have been neglected despite their importance for the successful colonisation of bamboo patches by non-bamboo plant species (Rother et al. 2009). However, patches dominated by bamboos may be unattractive to frugivorous birds because bamboos do not produce fleshy fruits. Possibly facilitated by anthropogenic disturbance (e.g. log- ging, harvesting of palm (Euterpe edulis) hearts) and natural disturbances (e.g. landslides, gaps resulting from tree falls), the native bamboo Guadua tagoara dominates large areas of the Atlantic forest in south-eastern Brazil, with an estimated total area CSIRO PUBLISHING Emu http://dx.doi.org/10.1071/MU12017 Journal compilation Ó BirdLife Australia 2013 www.publish.csiro.au/journals/emu