JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Nine hummingbird-pollinated species of Heliconia occur together at Finca La Selva, in the wet Caribbean lowlands of Costa Rica. In forest habitats, Heliconia clumps (clones) are typically small; in more open areas, many clumps attain large size. This probably reflects differences in light intensity and degree of vegetative competition in these habitats.Nine species of hummingbirds regularly visit Heliconia flowers at La Selva. The four hermits are nonterritorial, traplining foragers with long, curved bills. Non-hermits frequently hold territories at Heliconia clumps, and have short, straight bills. Pollination by hermits tends to produce more cross-pollination; territorial hummingbirds increase selfpollination. Different Heliconia species appear to be specialized for pollination by either hermits or non-hermits, largely through components of the caloric phenotype: amount and timing of nectar production, rate of inflorescence and flower production, and morphological parameters that affect the energetic efficiency of nectar-harvesting hummingbirds. Habitat may influence pollination systems through its effects on clump size and thus on the number of flowers a clump can have at any one time. Ultimately, specialization for hermits or nonhermits may depend on the degree of self-compatibility of the different Heliconia species.Hermit-pollinated Heliconia mostly show sequential and nonoverlapping flowering peaks, probably resulting from competition for pollinators and/or selection against hybridization. Two hermit-pollinated species bloom simultaneously, thereby inducing the birds to utilize an otherwise little-used microhabitat. Helicona species pollinated by non-hermits bloom in the early to middle rainy season, and are mostly separated by habitat.Isolating mechanisms among sympatric Heliconia species involve both spatial and temporal patterns of partitioning available pollinators. Floral parameters include mechanical (different site of pollen deposition on the bird) and ethological (caloric and visual factors affecting flower choice) mechanisms. Selection for pollinator specificity may result in convergence of blooming peaks, provided that other isolating mechanisms are present. Human activity has broken down some habitat barriers by producing large areas of second growth.

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The overall objective is to compare the ecological impact of bird-flower coevolution in different geographical areas. However, it is first necessary to define the parameters of such coevolution in broader terms than those of the traditional '^syndrome of ornithophily," which focuses very narrowly on some aspects of floral morphology. I recognize three distinct components of flower function: attraction, reward, and filtering mechanisms, and discuss their functioning in an ecological context, and as they relate to the genetic system or ''pollination unit" of the plant. Then I turn to nectarfeeding birds, and discuss not only morphological, but ecological and behavioral specializations to flowers as a food source. These discussions develop explicitly my criteria for detecting and evaluating bird-flower coevolution. The different groups of birds known to feed regularly (as opposed to opportunistically) on nectar are then compared according to these criteria, to determine their relative degrees of specialization for, and dependence upon, a high-nectar diet. Different groups are found to vary widely in their degrees of specialization for flower-feeding, and it is evident that bird-flower coevolution has followed very different courses, and led to widely divergent ecological systems in different geographical areas. By any criteria the hummingbirds are the most specialized avian nectarivores, although they are approached in this regard by some members of certain passerine groups, notably among the sunbirds. Several groups of passerine nectarivores also occur with the hummingbirds in many New World areas; these groups show low to moderate degrees of specialization for nectarivory, either as pollinators or as parasites on the hummingbird-flower system. The New World tropics thus present a wide range of specializations for flower-feeding in their avifauna, and represent a particularly interesting area for study. Patterns of ornithophily and nectarivory are thus examined in detail for this area, concentrating specifically on Southern Central America, especially Costa Rica. The altitudinal and geographical distributions of the two main groups of hummingbirds, the hermits and nonhermits, are found to differ, as are the taxonomic and ecological affinities of their primary foodplants. The hermits are most numerous in wet lowlands and the adjacent foothills, and are primarily associated with large monocotyledonous herbs, notably Heliconia. The nonhermits reach their greatest taxonomic and ecological diversity in the lower middle elevations, and are the only group present at high elevations; they seem to have coevolved with the flowers of a variety of dicot families, and the bromeliads among the monocots. Passerine nectarivores occur primarily as parasites on the hummingbird-flower system (Coerebidae) and are important as pollinators only in seasonally dry areas when the hummingbirds are poorly represented.Within the last ten to fifteen years the study of poHination has passed from a purely botanical pursuit to an extremely active...

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species-level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, including six ecological variables, 11 continuous morphological traits, and information on range size and location. Raw morphological measurements are presented from 90,020 individuals of 11,009 extant bird species sampled from 181 countries. These data are also summarised as species averages in three taxonomic formats, allowing integration with a global phylogeny, geographical range maps, IUCN Red List data and the eBird citizen science database. The AVONET dataset provides the most detailed picture of continuous trait variation for any major radiation of organisms, offering a global template for testing hypotheses and exploring the evolutionary origins, structure and functioning of biodiversity.

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Abstract. Phylogenetic community ecology combines phylogenetic hypotheses with local species composition and functional-trait information to evaluate historical and contemporary mechanisms influencing local assemblage structure. Most studies assume that, if functional traits are conserved, then patterns of trait variation should match patterns of phylogenetic structure within local assemblages. Here we evaluated if we could predict trait structure by assuming that environmental filtering or biotic interactions work primarily on phylogenetically conserved functional traits. We investigated patterns of phylogenetic assemblage structure and functional-trait variation in bill length, wing length, and body mass in 236 hummingbird assemblages (126 species) across two major gradients in northern South America: elevation and precipitation. While mean trait values for assemblages vary predictably based on empirical knowledge of hummingbird biology, the distribution of trait values within assemblages do not correspond to those predicted based on phylogenetic signal and phylogenetic structure. Instead, we were able to identify instances where assemblages have high levels of morphological variation despite their close evolutionary relatedness and vice versa. Our results provide support for both filtering and biotic interactions across gradients, as has been documented in other studies.

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