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We investigated the foraging ecology of 13 species of woodpecker in logged and unlogged lowland rain forest at two forest reserves in West Malaysia (Pasoh Forest Reserve and Sungai Lalang Forest Reserve). The parameters perch diameter and microhabitat/substrate type explained more variation in the data than other parameters, and effectively divided the guild into two groups: (1) 'conventional' -species that excavated frequently, used relatively large perches, and foraged on snags and patches of dead wood, and (2) 'novel' -species that used smaller perches and microhabitats that are available in tropical forests on a year-round basis (e.g. external, arboreal ant/termite nests and bamboo). These novel resources may explain, in part, the maintenance of high woodpecker diversity in tropical rain forests.

We investigated the microhabitat preferences and relative abundances of 13 species of woodpecker in Sungai Lalang Forest Reserve, West Malaysia. The availability of suitable microhabitat corresponded strongly with woodpecker abundance, and snags were the most highly preferred foraging substrate across species and study sites. Large amounts of necromass, including snags, were present in 5-y-old logged and unlogged forest, but dead wood was in low abundance in 10-y-old logged forest. The absence or scarcity of large, snag-foraging woodpeckers from older logged stands suggests that this resource may remain in low abundance for a considerable time.

Understanding foraging strategies of birds is essential to understanding mechanisms of their community assembly. To provide such information on a key Southeast Asian rainforest family, the babblers (Timaliidae), we evaluated foraging behavior and abundance in 7 morphologically and behaviorally similar sympatric species (Cyanoderma erythropterum, C. rufifrons, Stachyris maculata, S. nigricollis, S. poliocephala, Macronus ptilosus, and Mixornis gularis) in 5 habitats defined by structural complexity: (1) continuous native rainforest, (2) logged native rainforest fragments, (3) mature industrial tree plantation, (4) young industrial plantation, and (5) oil palm plantation. Enough data were obtained to compare abundance in all 7 species and foraging behavior in 5. All species were common in forest fragments and mature industrial tree plantations and less so in continuous rainforest and young industrial plantations; only M. gularis occurred in oil palm. In terms of foraging, M. gularis was the greatest generalist; C. rufifrons foraged mainly on live leaves in the forest midstory; and S. maculata, C. erythropterum, and M. ptilosus foraged mainly on dead leaves suspended in understory vegetation at significantly different heights. The dead-leaf substrate depends on a rich supply of falling leaves and extensive understory structure, conditions most common in native forest and old industrial plantations, and less so in mature forest, young plantations, and oil palm. Because of the importance of foraging data to understanding and managing biodiversity, we encourage the development of foraging fields in eBird (ebird.org), so that birdwatchers may help collect these relatively rare data.

Abstract:Altitudinal gradients provide tractable, replicated systems in which to study changes in species richness and community composition over relatively short distances. Previously, richness was often assumed to follow a monotonic decline with altitude, but recent meta-analyses show that more complex patterns, including mid-altitude richness peaks, are also prevalent in birds. In this study, we used point counts to survey birds at multiple altitudes on three mountains on the island of Borneo in Sundaland, an area for which quantitative analyses of avian altitudinal distribution are unavailable. In total we conducted 1088 point counts and collected associated habitat data at 527 locations to estimate species richness by altitude on Mt Mulu (2376 m), Mt Pueh (1550 m) and Mt Topap Oso (1450 m). On Mulu, the only mountain with an intact habitat gradient, bird species richness peaks at 600 m. Richness appeared to peak at 600 m on Totap Oso as well, but on Pueh it peaked several hundred metres higher. The richness peak on Mulu differs from that predicted by null models and is instead caused by the overlap of distinct lowland and montane avifaunas, supporting the faunal overlap hypothesis. This finding provides further evidence that a lack of coincidence between peak turnover and peak richness is not sufficient evidence to rule out faunal overlap as a causal factor.

Aim The traditional view of species’ distributions is that they are less abundant near the edges of their ranges and more abundant towards the centre. Testing this pattern is difficult because of the complexity of distributions across wide geographical areas. An alternative strategy, however, is to measure species’ distributional patterns along elevational gradients. We applied this strategy to examine whether lowland forest birds are indeed less common near their upper range limits on a Bornean mountain, and tested co‐occurrence patterns among species for potential causes of attenuation, including signatures of habitat selection and competition at the periphery of their ranges. Location Mt. Mulu, Borneo. Taxon Rain forest birds. Methods We surveyed lowland forest birds on Mt. Mulu (2,376 m), classified their elevation‐occupancy distributions using Huisman–Olff–Fresco (HOF) models, and examined co‐occurrence patterns of species pairs for signatures of shared habitat patches and interspecific competition. Results For 39 of 50 common species, occupancy was highest at sea level then gradually declined near their upper range edges, in keeping with a “rare periphery” hypothesis. With respect to habitat selection, lowland species do not appear to cluster together at sites of patchy similar habitat near their upper range limits; neither are most lowland species segregated from potential montane competitors where ranges overlap. Main conclusions High relative abundance at sea level implies that species inhabit “truncated niches” and are not currently near the limits of their fundamental niche, unless unknown critical response thresholds exist. However, indirect effects of increasing temperature predicted under climate change scenarios could still influence lower range limits of lowland species indirectly by altering habitat, precipitation regimes and competitive interactions. The lack of non‐random co‐occurrence patterns implies that patchy habitat and simple pairwise species interactions are unlikely to be responsible for upper range limits in most species; diffuse competition across diverse rain forest bird communities could still play a role.