Scientists have long been trying to understand why the Neotropical region holds the highest diversity of birds on Earth. Recently, there has been increased interest in morphological variation between and within species, and in how climate, topography, and anthropogenic pressures may explain and affect phenotypic variation. Because morphological data are not always available for many species at the local or regional scale, we are limited in our understanding of intra‐ and interspecies spatial morphological variation. Here, we present the ATLANTIC BIRD TRAITS, a data set that includes measurements of up to 44 morphological traits in 67,197 bird records from 2,790 populations distributed throughout the Atlantic forests of South America. This data set comprises information, compiled over two centuries (1820–2018), for 711 bird species, which represent 80% of all known bird diversity in the Atlantic Forest. Among the most commonly reported traits are sex (n = 65,717), age (n = 63,852), body mass (n = 58,768), flight molt presence (n = 44,941), molt presence (n = 44,847), body molt presence (n = 44,606), tail length (n = 43,005), reproductive stage (n = 42,588), bill length (n = 37,409), body length (n = 28,394), right wing length (n = 21,950), tarsus length (n = 20,342), and wing length (n = 18,071). The most frequently recorded species are Chiroxiphia caudata (n = 1,837), Turdus albicollis (n = 1,658), Trichothraupis melanops (n = 1,468), Turdus leucomelas (n = 1,436), and Basileuterus culicivorus (n = 1,384). The species recorded in the greatest number of sampling localities are Basileuterus culicivorus (n = 243), Trichothraupis melanops (n = 242), Chiroxiphia caudata (n = 210), Platyrinchus mystaceus (n = 208), and Turdus rufiventris (n = 191). ATLANTIC BIRD TRAITS (ABT) is the most comprehensive data set on measurements of bird morphological traits found in a biodiversity hotspot; it provides data for basic and applied research at multiple scales, from individual to community, and from the local to the macroecological perspectives. No copyright or proprietary restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications or teaching and educational activities.

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A decline in species number often occurs after forest fragmentation and habitat loss, which usually results in the loss of ecological functions and a reduction in functional diversity in the forest fragments. However, it is uncertain whether these lost ecological functions are consistently maintained throughout continuous forests, and so the importance of these functions in continuous forests remains unknown. Point counts were used to assess both the taxonomic and functional diversity of specialist and generalist birds from sampling in a continuous primary forest compared with forest fragments in order to investigate the responses of these groups to forest fragmentation. We also measured alpha and beta diversity. The responses of specialists and generalists were similar when we assessed all bird species but were different when only passerines were considered. When examining passerines we found lower total taxonomic beta diversity for specialists than for generalists in the continuous forest, while taxonomic beta diversity was higher in the fragmented forest and similar between bird groups. However, total functional beta‐diversity values indicated clearly higher trait regularity in continuous forest for specialists and higher trait regularity in fragments for generalists. Specialists showed significantly higher functional alpha diversity in comparison with generalists in the continuous forest, while both groups showed similar values in fragments. In passerines, species richness and alpha functional diversity of both specialist and generalist were explained by forest connectivity; but, only fragment size explained those parameters for specialist passerines. We suggest that considering subsets of the community with high similarity among species, as passerines, provides a better tool for understanding responses to forest fragmentation. Due to the regularity of specialists in continuous forest, their lost could highly affect functionality in forest fragments.

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The delineation of unique areas in biodiversity is crucial for conservation planning. However, identification of distinct biotas is a challenging task. In this study, we use an objective analytical process to test if bird and plant species composition of three different forest formation in the Atlantic forest Biome is sufficiently distinct to merit the recognition of ecoregions. We also evaluated how current climatic and spatial factors shape the distribution of plants and birds. Sampling localities were selected in three forest types of southern Brazil: mixed rain forest (MF), seasonal semi‐deciduous forest (SF) and dense rain forest (DF). The point‐centred quarter method and point counts were used to sample plants and birds respectively. Multivariate analyses were used to evaluate species composition, while the Rank Occupancy Abundance Profile was used to determine the association of bird species with each forest type. We used variation partitioning to determine which factors, that is climatic, spatial or tree species abundance (in the case of birds) better explained the distribution of plants and birds. A total of 176 tree species and 270 bird species were recorded. The bird species composition was sufficiently distinct among the three forest types, but the plant species composition was only distinct between DF and MF. Moreover, 61% of bird species were associated with only one forest type. This high association and the different species composition suggest that these forest types are sufficiently distinct to merit the recognition of ecoregions. Plant distribution was mainly affected by climatic variables, while bird distribution was mainly influenced by forest type and less so by climatic variables. Our data suggest that all three forest types should be conserved, but conservation strategies are urgent in MF where only 0.39% of its original cover is under protection.

We propose an index of bird detectability that can improve the selection of more suitable species to be used for evaluating habitat integrity. Bird surveys were conducted in a conservation unit, the Parque Estadual Mata dos Godoy, southern Brazil. We ranked the bird species according to detectability index, which allowed us to establish two groups: species with low detectability (SLD) and species with high detectability (SHD).We also tested some features that are frequently associated with bird species of high detectability. Sound frequency was the attribute more clearly associated with detectability. We found a negative correlation between sound frequency and detectability, especially within certain groups, i.e. Tyrannidae. In our studied system we recognized Aratinga auricapillus as the best biological indicator among the studied birds, due its high vulnerability and high detectability.

Along a distance gradient from a given river, two types of habitat can be recognized: natural river edge and forest interior, each one with its own vegetation characteristics and dynamics. In a continuous area of the Brazilian Atlantic Forest, we investigated (1) if bird communities are different between a riverbank of a small stream and an inland forest habitat; (2) if the species of the river edge habitat are the ones that persist in the most in forest fragments after deforestation of a continuous forest; (3) if the river edge habitat species are those that are less sensitive to forest fragmentation. It is expected that there are differences in the bird communities and the occupancy of some species between the two habitats. We allocated 16 sampling points in each of the habitats and sampled the birds by point counts with a short radius of 30 m. Results suggest that there is a significant difference between the composition of the bird communities of the river edge and forest interior habitats, although the species richness is similar. Six species were more likely to occupy the river edge and 14 species had a greater probability of occupancy in the forest interior. Species associated with the river edge habitat (15 species) tend not to be sensitive to forest fragmentation (12 species). In this study, we demonstrated that river-border species of continuous forest areas form a significant part of the bird communities that persist in small forest fragments, with intense edge effect. This shows that not all forest edge species are the result of the colonization from open areas. Congruently, species that occupy the most distant areas from the river vegetation in a continuous forest are those more sensitive to forest fragmentation. KEYWORDS: Atlantic Rainforest, bird sensitivity, forest interior, natural edge, probability of occupancy. tree species; also, it is common to have the fall of trees and consequently the creation of clearings that allow the occupation of bamboo species (Bianchini et al. 2001, Anjos et al. 2007). This lowland riparian environment constitutes a transition between the river and the associated upland forest, marking a natural border or ecotone boundary. A forest ecotone is a consequence of the meeting of distinct natural plant communities, which, in turn, influences the diversity of wild animals across the landscape, dependent on distance from a rivers' edge and the characteristic transition in topography, plant community, hydrological regimes, and soil types (Naiman et al. 1993, Shirley 2005). Considering several taxonomic groups, some studies suggest greater species richness in riparian environments compared to distinct forest (Naiman et al. 1993), others found greater richness in non-riparian environments (McGaragal & McComb 1992, Peres 1997) and some found no difference between these two habitat types (Gomez & Anthony 1998, Rykken et al. 2007). On birds, several studies indicated the great importance of the riparian environment (natural river edges) as a uniquely sustaining habitat with relat...

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