Structure and Organization of an Amazonian Forest Bird Community

Abstract

To help fill the gap in detailed knowledge of avian community structure in tropical forests, we undertook a census of a 97 -ha plot of floodplain forest in Amazonian Peru. The plot was censused over a 3-mo period spanning the 1982 breeding season. The cooperative venture entailed ::::::12 person-months of effort. Conventional spot-mapping was the principal method used, but several additional methods were required to estimate the numbers of non-territorial and group-living species: direct counts of the members of mixed flocks, saturation mist-netting of the entire plot, opportunistic visual registrations at fruiting trees, determination of the average size of parrot flocks, color banding of colonial icterids, etc.Two hundred forty-five resident species were found to hold territories on the plot, or to occupy all or part of it. Seventy-four additional species were detected as occasional-tofrequent visitors, wanderers from other habitats, or as migrants from both hemispheres. By superimposing territory maps or the areas of occupancy of individual species, we determined that point (alpha) diversities exceeded 160 species in portions of the plot. About 1910 individual birds nested in 100 ha of this floodplain forest, making up a biomass conservatively estimated at 190 kglkm 2 • The total number ofbreeding birds was equivalent to that in many temperate forests, but the biomass was about five times as great. Predominantly terrestrial granivores contributed the largest component of the biomass (39%), followed by largely arboreal frugivores (22%). Considering only insectivores, the biomass (34 kg!km 2 ) is somewhat less than that in the forest at Hubbard Brook, New Hampshire (40 kg!km 2 ), although it is greater (55 kglkm 2 ) if one includes omnivores. The number of insectivores was considerably less than at Hubbard Brook, due to their 60% larger average body size (32 vs. 20 g).Even though a large majority of the species were patchily distributed, the 97 -ha plot was found to include 99% of the bird species that regularly occupy mature floodplain forest at Cocha Cashu. The most abundant species occupied territories of 4-5 ha, and 84 species (26%) had population densities of :o; 1 pair per square kilometre. Of these, 33 (10% of the total community) were judged to be constitutively rare (i.e., having low population densities everywhere), rather than being merely locally rare. Many of these are predicted to be vulnerable to forest fragmentation and disturbance. Comparison of these results with those from other tropical forests proved difficult due to a lack of standardized methodology.

Species abundance patterns in an ecosystem simulation studied through Fisher’s logseries

“…(a) A highly diversified community, as Manu, produces a curve with a gentle slope; this is the same for Korup, BCI 1982, 1985, 1990, Lambir 1992, 1997, and Paso 1987, 1990 . An important repercussion of this dichotomy based on species richness is that a more diverse community provides more samples fitting the logseries, which has also been observed by ecologists [21,68,70].…”

Biologia de aves capturadas em um fragmento de Mata Atlântica, Igarassu, Pernambuco, Brasil

“…As guildas alimentares foram agrupadas em cinco categorias: Onívoras (O), Granívoras (G), Insetívoras (I), Frugívoras (F) e Nectarívoras (N), seguindo WILLIS (1979), TERBORGH et al (1990), SICK (1997) e SIGRIST (2006).…”

Effects of forest heterogeneity on occurrence and abundance of the scale-backed antbird, Hylophylax poecilinotus (Aves: Thamnophilidae), in the Amazon forest

“…It has been suggested that local variations in the forest structure may be important ecological factors affecting their habitat use (ORIANS 1969, WILLIS 1977, REMSEN & PARKER 1983, TERBORGH 1985, KARR et al 1990, TERBORGH et al 1990, CINTRA 1997, BORGES et al 1999, CINTRA et al 2006, BANKS & CINTRA 2008.…”

“…According to ecological theory, a key factor to describe the niche of bird species is the understanding of how habitat structure influences avian populations and communities (MACARTHUR et al 1966, MARTIN 1985, TERBORGH et al 1990). The effects of habitat heterogeneity on birds have been investigated in terms of the relationships between variability of vegetation and diversity of avian species, which may be a consequence of niche availability (MACARTHUR & MACARTHUR 1961, MARTIN 1985.…”

“…Studies on habitat use by birds in tropical rainforests have also focused on factors affecting richness and abundance of species and most of the studies on effects of vegetation on birds have concentrated on habitat partitioning by species (REMSEN & PARKER 1983, TERBORGH 1985, and on the effects of vegetation structure on bird guilds or communities (PEARSON 1975, HOWE & SMALLWOOD 1982, TERBORGH et al 1990, LOISELLE & BLAKE 1991. However, few studies have investigated how micro-habitat structure and resource availability affect individual species (but see TERBORGH 1985, CINTRA 1997.…”