The phylogenetic and functional diversity of regional breeding bird assemblages is reduced and constricted through urbanization

Urbanization reduces diversity, simplifies community and filter bird species based on their functional traits in a tropical city

Understanding how organisms are coping with major changes imposed by urban intensification is a complex task. In fact, our understanding of the impacts of urbanization on biodiversity is scarce in the global south compared to the north. In this study, we evaluated how bird communities are affected by impact of urban intensification in a tropical city. Thus, we assessed whether increased urban intensification 1) jeopardizes bird diversity (taking into account taxonomic-TD, phylogenetic-PD, and functional-FD dimensions), 2) drives changes in bird community composition and enables the detection of indicator species of such impact, and 3) leads to changes in bird functional traits linked to reproduction, resource acquisition, and survival. We found that urban intensification has a direct impact on the bird community, reducing all three types of diversity. Communities in areas of greater urban intensity are represented by fewer species, and these species are PD and FD less distinct. In addition, we detected at least ten species of areas of lower urban intensity that proved to be more sensitive to urban intensification. With regard to bird traits, we found no significant responses from reproductive, habitat use and feeding variables. Body weight and tail length were the only variables with significant results, with higher urbanization intensity areas selecting for species with lower weights and longer tails. Given the global biodiversity loss we are observing, this information can guide urban managers and planners in designing urban landscapes to maintain biodiversity in cities.

Birds of Berlin: Changes in communities and guilds in the urban park "Tiergarten" since 1850

Urbanization has far-reaching consequences on birds, and knowledge of the impacts on taxonomic and functional diversity is necessary to make cities as compatible as possible for species. Avian diversity in parks in urban centers has been investigated multiple times, but rarely so in long-term studies due to lacking data. The Tiergarten in Berlin is a large-scale park in the city center of great value for people and many species including birds. We compiled bird species lists since 1850 and from monitoring in 2022 in one dataset to investigate how bird communities and guilds have changed over time and how these alterations were influenced by the eventful history of the park's vegetation conditions. Long-term changes in species assemblages were analyzed with an ordination analysis, and changes in guild presence and functional richness were discussed with regard to landscape transitions. A gradual development of species assemblages yet only small changes in guild composition since 1850 was detected, whereas the 1950 community stands out with a drop in species richness and replacement of forest species with an open land community, which reflects the deforestation of the park during World War II. Consideration of habitat, lifestyle, trophic, and migration guilds revealed no sign of functional homogenization over the last 172 years (1850-2022). Despite the high frequentation of the park by humans it still allows for a high bird diversity due to the Tiergarten's sheer size and heterogeneity of vegetation and habitats. We recommend that the park is maintained and managed accordingly to preserve this condition and advise other urban parks to strive for these beneficial features.

Urbanization drives biotic homogenization of the avian community in China

Urbanization-driven biotic homogenization has been recorded in various ecosystems on local and global scales; however, it is largely unexplored in developing countries. Empirical studies on different taxa and bioregions show conflicting results (i.e. biotic homogenization vs. biotic differentiation); the extent to which the community composition changes in response to anthropogenic disturbances and the factors governing this process, therefore, require elucidation. Here, we used a compiled database of 760 bird species in China to quantify the multiple-site β-diversity and fitted distance decay in pairwise β-diversities between natural and urban assemblages to assess whether urbanization had driven biotic homogenization. We used generalized dissimilarity models (GDM) to elucidate the roles of spatial and environmental factors in avian community dissimilarities before and after urbanization. The multiple-site β-diversities among urban assemblages were markedly lower than those among natural assemblages, and the distance decays in pairwise similarities in natural assemblages were more rapid. These results were consistent among taxonomic, phylogenetic, and functional aspects, supporting a general biotic homogenization driven by urbanization. The GDM results indicated that geographical distance and temperature were the dominant predictors of avian community dissimilarity. However, the contribution of geographical distance and climatic factors decreased in explaining compositional dissimilarities in urban assemblages. Geographical and environmental distances accounted for much lower variations in compositional dissimilarities in urban than in natural assemblages, implying a potential risk of uncertainty in model predictions under further climate change and anthropogenic disturbances. Our study concludes that taxonomic, phylogenetic, and functional dimensions elucidate urbanization-driven biotic homogenization in China.

Woody species composition, diversity, and ecosystem services of yards along an urban socioeconomic gradient

Woody plants offer a wide range of valuable ecosystem services, but their distribution across socioeconomic gradients in urban landscapes remains poorly understood. Thus, we explored the effect of socioeconomic and legacy factors on plant species richness and phylogenetic diversity, and the motivations for growing and keeping certain species. We sampled a total of 300 households across a socioeconomic gradient in the city of Harare, Zimbabwe, in high-, medium- and low-density areas, representing low to high wealth strata. Trees were mostly grown for ornamental purpose in the rich (low-density) suburbs and utilitarian purposes in the poorer medium to high-density areas. However, trees were also grown with similar proportion for shade across the socioeconomic gradient. Proportion of medicinal and fruit trees increased with household density, while wind break trees were more common in low-density suburbs. Exotic species exhibited greater species richness compared with indigenous species, with both combined and separate assessments of indigenous and exotic species richness revealing a significant positive association with socioeconomic and legacy factors. The composition of species displayed considerable variation along the socioeconomic gradient. Notably, in low-density environments, exotic species maintained elevated phylogenetic diversity in comparison to indigenous species. This distinction was particularly pronounced when analysed independently, revealing a significant positive correlation between exotic species richness and both property value and education level. Our study shows that residents filter specific plant species based on their socioeconomic status and that, relative to low-income households, the rich homeowners have unintentionally incorporated enough exotic species to produce novel phylogenetic diversity of woody plants in their yards. Thus, we confirm the existence of a socioeconomic gradient in terms of species richness, composition, and phylogenetic diversity. However, the imbalance in species richness and phylogenetic diversity across the socioeconomic gradient can be reduced by increased tree planting in open areas, including along streets in medium to high-density areas to improve ecosystem services.

Geographic variations in eco-evolutionary factors governing urban birds: The case of university campuses in China

Urbanization alters natural habitats, restructures biotic communities and serves as a filter for selecting species from regional species pools. However, empirical evidence of the specific traits that allow species to persist in urban areas yields mixed results. More importantly, it remains unclear which traits are widespread for species utilizing urban spaces (urban utilizers) and which are environment-dependent traits. Using 745 bird species from 287 university/institute campuses in 74 cities and their species pools across China, we tested whether species that occur in urban areas are correlated with regards to their biological (body mass, beak shape, flight capacity and clutch size), ecological (diet diversity, niche width and habitat breadth), behavioural (foraging innovation) and evolutionary (diversification rate) attributes. We used Bayesian phylogenetic generalized linear mixed models to disentangle the relative roles of these predictors further, and to determine the extent to which the effects of these predictors varied among different cities. We found that urban birds were more phylogenetically clustered than expected by chance, and were generally characterized by a larger habitat breadth, faster diversification rate, more behavioural innovation and smaller body size. Notably, the relative effects of the attributes in explaining urban bird communities varied with city temperature and elevation, indicating that the filters used to determine urban species were environment dependent. We conclude that, while urban birds are typically small-sized, generalists, innovative and rapidly diversifying, the key traits that allow them to thrive vary spatially, depending on the climatic and topographic conditions of the city. These findings emphasize the importance of studying species communities within specific cities to better understand the contextual dependencies of key traits that are filtered by urban environments.

The surface urban heat island effect decreases bird diversity in Chinese cities

The audiovisual experience of observing birds in cities provides numerous benefits to residents, but their diversity is endangered by urbanization. Although the magnitude of the surface urban heat island effect (hereafter SUHI) has grown in recent years, its impact on bird diversity has not been adequately investigated. Here, we calculate the SUHI in 336 Chinese cities and we document the implications of the SUHI for avian species richness and functional diversity during the 2001, 2011, and 2019 breeding and non-breeding seasons. We predict that the SUHI will result in greater species richness and functional diversity in urban areas during the non-breeding season, especially for cities located within colder regions of China where the SUHI is more likely to relax thermoregulatory costs and reduce the propensity of some species to migrate. We predict that the SUHI will result in decreased species richness and functional diversity during the breeding season due to increased physiological stress, especially for cities located within warmer regions of China. Our findings showed that the SUHI was associated with lower species richness and lower functional diversity of birds in urban areas compared to suburban areas during both the breeding and non-breeding seasons. These results suggest that the SUHI induced birds to avoid urban areas or to move to cooler suburban areas during both the breeding and non-breeding seasons. This effect persisted irrespective of a city's size or geographical location. Our findings suggest that the SUHI is degrading bird diversity in Chinese cities.

Collections of small urban parks consistently support higher species richness but not higher phylogenetic or functional diversity

When prioritizing regions for conservation protection, decisions are often based on the principle that a single large reserve should support more species than several small reserves of the same total area (SLOSS). This principle remains a central paradigm in conservation planning despite conflicting empirical evidence and methodological concerns. In urban areas where small parks tend to dominate and policies to promote biodiversity are becoming increasingly popular, determining the most appropriate prioritization method is critical. Here, we document the role of SLOSS in defining the seasonal diversity of birds in 475 parks in 21 US cities. Collections of small parks were consistently associated with higher species richness, spatial turnover and rarity. Collections of both small and large parks were associated with higher phylogenetic and functional diversity whose patterns varied across seasons and cities. Thus, collections of small parks are a reliable source of species richness driven by higher spatial turnover and rarity, whereas collections of both small and large parks contain the potential to support higher phylogenetic and functional diversity. The presence of strong intra-annual and geographical variation emphasizes the need for regional prioritization strategies, where multiple diversity metrics are examined across parks and seasons.

Urbanisation generates multiple trait syndromes for terrestrial animal taxa worldwide

Cities can host significant biological diversity. Yet, urbanisation leads to the loss of habitats, species, and functional groups. Understanding how multiple taxa respond to urbanisation globally is essential to promote and conserve biodiversity in cities. Using a dataset encompassing six terrestrial faunal taxa (amphibians, bats, bees, birds, carabid beetles and reptiles) across 379 cities on 6 continents, we show that urbanisation produces taxon-specific changes in trait composition, with traits related to reproductive strategy showing the strongest response. Our findings suggest that urbanisation results in four trait syndromes (mobile generalists, site specialists, central place foragers, and mobile specialists), with resources associated with reproduction and diet likely driving patterns in traits associated with mobility and body size. Functional diversity measures showed varied responses, leading to shifts in trait space likely driven by critical resource distribution and abundance, and taxon-specific trait syndromes. Maximising opportunities to support taxa with different urban trait syndromes should be pivotal in conservation and management programmes within and among cities. This will reduce the likelihood of biotic homogenisation and helps ensure that urban environments have the capacity to respond to future challenges. These actions are critical to reframe the role of cities in global biodiversity loss.

Introduction of artificial light at night increases the abundance of predators, scavengers, and parasites in arthropod communities

While recent studies explore the negative impacts of light pollution on arthropods, few studies investigated community-level responses to artificial light. Using an array of landscaping lights and pitfall traps, we track community composition over 15 consecutive days and nights, including a five-night pre-light period, a five-night during-light period, and a five-night post-light period. Our results highlight a trophic-level response to artificial nighttime lighting with shifts in the presence and abundance of predators, scavengers, parasites, and herbivores. We show that associated trophic shifts occurred immediately upon the introduction of artificial light at night and are limited to nocturnal communities. Lastly, trophic levels reverted to their pre-light state, suggesting many short-term changes in communities are likely the result of behavioral shifts. These trophic shifts may become common as light pollution increases, implicating artificial light as a cause of global arthropod community change and highlighting light pollution's role in global herbivorous arthropod decline.

Concordant and opposing effects of climate and land-use change on avian assemblages in California's most transformed landscapes

Climate and land-use change could exhibit concordant effects that favor or disfavor the same species, which would amplify their impacts, or species may respond to each threat in a divergent manner, causing opposing effects that moderate their impacts in isolation. We used early 20th century surveys of birds conducted by Joseph Grinnell paired with modern resurveys and land-use change reconstructed from historic maps to examine avian change in Los Angeles and California's Central Valley (and their surrounding foothills). Occupancy and species richness declined greatly in Los Angeles from urbanization, strong warming (+1.8°C), and drying (-77.2 millimeters) but remained stable in the Central Valley, despite large-scale agricultural development, average warming (+0.9°C), and increased precipitation (+11.2 millimeters). While climate was the main driver of species distributions a century ago, the combined impacts of land-use and climate change drove temporal changes in occupancy, with similar numbers of species experiencing concordant and opposing effects.

Evaluation of urban expansion and the impacts on vegetation in Chinese Loess Plateau: a multi-scale study

Vegetation degradation caused by rapid urban expansion is a pressing global challenge. Focusing on the Chinese Loess Plateau (CLP), we use satellite observations from 2000 to 2017 to evaluate the spatiotemporal pattern of urban expansion, and its imprint on vegetation across old urban, new urban, urban, non-urban areas as well as the entire urbanization intensity (UI) gradient (from 0 to 100%). We found a massive increase of urban impervious surface area (UISA) in the CLP from 2000 to 2017, and an uneven expansion of UISA at different urban agglomerations and cities. Less green were found in urban and new urban areas, while old urban and non-urban areas generally showed an improved greening pattern. In addition, the annual maximum EVI (EVI_max) differences between urban and non-urban areas were - 0.0995 on average from 2000 to 2017. The Guanzhong Plain urban agglomeration (GPUA) witnessed the most significant EVI_max differences (- 0.120), and the Ningxia Yanhuang urban agglomeration (NYUA) witnessed the lowest EVI_max differences (- 0.012). The EVI_max showed significantly decreased trends along the entire spectrum of urbanization gradient for 97.4% (38 of 39) cities and five urban agglomerations. The most significant decrease was found in the GUPA (slope =  - 0.0197/10a, p < 0.01), while the smallest drop was found in the NYUA (slope =  - 0.011/10a, p < 0.01). This study offered a fundamental support for understanding the vegetation variation along the urban-rural gradient, which may help stakeholders to make better ecological management policies for urban vegetation in ecologically fragile areas.

Urban parks are a refuge for birds in park-poor areas

Urban parks provide amenities that support both human and animal communities. However, parks are often unevenly distributed within cities. One metric used to assess the distribution of parks to the public is termed the Park Score. The Park Score is an approach to measure access, acreage, investment, and amenities, and is designed to understand a city’s needs for greenspace, with a major focus on public health. In addition to issues related to public health, a disparity in the distribution of urban parks may pose a barrier for wildlife, such as birds. Yet, this remains unclear. We designed a study to quantify the role of parks in providing a refuge for birds across a park-needs gradient in Greater Los Angeles (LA), a metropolis with one of the lowest park scores in the United States. We had two objectives to address our goal. First, we quantified patterns in habitat features and avian communities within and adjacent to parks. Second, we analyzed relationships among habitat features within and adjacent to parks on avian abundance. We sampled birds and habitat features at 48 parks across a park-needs gradient in L.A. from October to March of 2017/2018 and 2018/2019. We found three lines of evidence supporting the refugia effect of parks. First, habitat features within parks were similar between low- and high-needs areas of LA, and this likely influenced avian abundance patterns, which were also alike. Second, avian communities were generally similar across the park-needs gradient, where parks in high-needs areas harbored birds affiliated with forest and shrub ecosystems. Third, bird abundance patterns were related to numerous habitat features within parks, regardless of where parks occurred in the city. The patterns we uncovered were opposite to what is found in residential areas (i.e., luxury effect), suggesting that parks provide important habitat for birds, whether in high- or low-needs sections of LA. Our results stress the role of parks as refugia in park-poor areas because they provide habitat in otherwise inhospitable urban conditions. Continued investment in park development in high-needs areas can thus potentially be a win-win when considering the benefits to people and birds.

Urbanisation and land-cover change affect functional, but not compositional turnover of bird communities

Land-use and land-cover change strongly affect biodiversity patterns and are assumed to be growing threats in the future. Particularly increasing urbanisation may affect species turnover and functional composition of biological communities. This study aimed to assess the characteristics of land-cover change in a medium-sized urban municipality from 2011 to 2018, and the effects of urbanisation on avian species- and functional diversity. The study was performed in Trondheim (Norway), using local land-cover maps and GBIF bird species occurrence records. GLMMs were used to model species turnover as a function of urbanisation, and the probability of species appearance and disappearance based on urbanisation and species traits. The extent of bird species turnover within a municipality-wide 500 × 500m2 grid was not predicted by a changes in developed area, but the probability of disappearance and appearance of bird species varied with urbanisation and bird functional traits. Species associated with urban- or open areas showed a decreasing probability of disappearing and an increasing probability of appearing with increasing amount of developed area within grid cells. Similarly, granivorous species showed a decreasing probability of disappearing. Species feeding above ground-level showed positive responses to changes in land-cover. The probability of both appearance and disappearance, thus species turnover, increased with increasing longevity. Most functional groups respond negatively to increasing urbanisation, indicating a potential impoverishment of local avifauna with future land-cover modifications. Considering planned future land-cover changes within the municipality, the local avian communities are in danger of homogenisation. The recommendations for local management are to minimise conversion of vulnerable habitats, such as wetlands and woodlands, in particular if these are converted to developed area.

Winter thriving: on the role of a boreal city on bird communities

Information on how urban areas affect bird communities during winter in the boreal region is still scarce. With the aim of assessing such role of the urban habitats on over-wintering boreal birds, I focused on a city-wide approach in the city of Lahti (southern Finland) and two nearby forests (as controls). Point count surveys were conducted in 157 sites within the city and 30 in the control forests. In order to achieve comparable sets of data to contrast with the reference forests, I randomly selected five 30 point count sub-samples from the Lahti city-wide survey. Species richness was, in general, higher in the sub-samples from the city of Lahti. Such pattern did not show relationship with the built cover of the studied sites. Bird abundances were 3.3–5.9 times higher in the urban sub-samples when contrasted with the forest ones. Although results of this study are limited to a single city and consider one wintering season, they clearly illustrate the important role of urban systems as habitat for wintering birds in boreal systems.

Taxonomic, Phylogenetic and Functional Diversity of Bird Assemblages in Urban Green Spaces: Null Model Analyses, Temporal Variation and Ecological Drivers

Urban expansion is a pervasive driver of biodiversity loss. To understand the effects of urbanization on diversity, we investigated the response of bird taxonomic, phylogenetic, and functional diversity to urban green spaces’ characteristics in thirty-one green spaces of Mexico City. Selected sites encompassed variation of environmental factors along a transformation gradient, from natural protected areas to landscaped parks. Bird observations were conducted during winter (non-breeding season), spring (dry breeding season), and summer (wet breeding season). We used multi-model inference to assess the relationship of green space area, shape, isolation, tree richness, habitat diversity, and vegetation cover with species richness, Faith’s phylogenetic diversity, and functional richness. We calculated standardized effect sizes from null models to assess phylogenetic and functional structure. We registered 91 species belonging to 28 families across all sites and seasons. The number of detected species was largest in winter and decreased toward the dry breeding season, and then toward the wet breeding season. We found a moderate to strong positive relationship of species richness with phylogenetic diversity and functional richness. Overall, phylogenetic and functional structure of bird communities in green spaces was neither clustered nor over-dispersed. However, few cases of functional clustering, phylogenetic clustering, or both were observed, and they corresponded to natural protected areas. Results showed a predominant role of green space area in determining community diversity and phylogenetic structure while it did not influence functional structure. Contrary to our predictions, habitat diversity had a negative effect on species richness and phylogenetic diversity and this effect was detected only during the wet breeding season, whereas isolation showed a positive relationship with phylogenetic and functional structure, during the wet breeding season and winter, respectively. This study emphasizes the use of complementary measures of diversity together with the comparison between observed and expected values to get a better insight into the mechanisms by which green spaces’ characteristics affect bird diversity across the seasons.

Keys to the city: an integrative conceptual framework on avian urban filtering

Urbanization represents a multi-dimensional ecological ‘filter’ for birds determined by a myriad of variables that can change over time. Birds colonising an urban system or staying in a habitat that has been recently urbanised need to overcome both the extrinsic (e.g. food predictability, human activities, and inter-specific interaction) and intrinsic filter variables, ranging from genetic to behavioural changes and/or adjustments. An increasing body of knowledge has identified the behavioural component as crucial for individuals facing the spatiotemporal dynamic urban filters, often after other traits and mechanisms have played their role. Through both developmental (i.e. variability in the expression of genes during ontogeny) and activation plasticity (i.e. alteration of behaviour as a result of individual experience), studies have shown that the identification of cues in novel systems—often determined by extrinsic factors—and learning processes, among other factors, have important impacts on decision-making and innovation. The latter are crucial behavioural traits for thriving in urban settings. Thus, we propose an integrative mechanistic framework based on the process experienced by birds who reach a city and manage to persist in the novel system (becoming urban ‘utilisers’) or those that dwell in an urbanised region who increase their fitness through behavioural responses and adaptations, leading to population persistence (becoming ‘dwellers’). Future field research efforts ought not only to widen the range of focal species, regions, and temporal scales of studies, but also to assess behavioural responses in highly urbanised settings, given that much of our knowledge comes from studies performed in urban greenspaces. Additionally, experimental studies are needed to complement the evidence from field research and to determine causal links.

Residential yard management and landscape cover affect urban bird community diversity across the continental USA

Urbanization has a homogenizing effect on biodiversity and leads to communities with fewer native species and lower conservation value. However, few studies have explored whether or how land management by urban residents can ameliorate the deleterious effects of this homogenization on species composition. We tested the effects of local (land management) and neighborhood-scale (impervious surface and tree canopy cover) features on breeding bird diversity in six US metropolitan areas that differ in regional species pools and climate. We used a Bayesian multiregion community model to assess differences in species richness, functional guild richness, community turnover, population vulnerability, and public interest in each bird community in six land management types: two natural area park types (separate and adjacent to residential areas), two yard types with conservation features (wildlife-certified and water conservation) and two lawn-dominated yard types (high- and low-fertilizer application), and surrounding neighborhood-scale features. Species richness was higher in yards compared with parks; however, parks supported communities with high conservation scores while yards supported species of high public interest. Bird communities in all land management types were composed of primarily native species. Within yard types, species richness was strongly and positively associated with neighborhood-scale tree canopy cover and negatively associated with impervious surface. At a continental scale, community turnover between cities was lowest in yards and highest in parks. Within cities, however, turnover was lowest in high-fertilizer yards and highest in wildlife-certified yards and parks. Our results demonstrate that, across regions, preserving natural areas, minimizing impervious surfaces and increasing tree canopy are essential strategies to conserve regionally important species. However, yards, especially those managed for wildlife support diverse, heterogeneous bird communities with high public interest and potential to support species of conservation concern. Management approaches that include the preservation of protected parks, encourage wildlife-friendly yards and acknowledge how public interest in local birds can advance successful conservation in American residential landscapes.

Intensive human land uses negatively affect vertebrate functional diversity

Land-use change is the leading driver of global biodiversity loss thus characterising its impacts on the functional structure of ecological communities is an urgent challenge. Using a database describing vertebrate assemblages in different land uses, we assess how the type and intensity of land use affect the functional diversity of vertebrates globally. We find that human land uses alter local functional structure by driving declines in functional diversity, with the strongest effects in the most disturbed land uses (intensely used urban sites, cropland and pastures), and among amphibians and birds. Both tropical and temperate areas experience important functional losses, which are only partially offset by functional gains. Tropical assemblages are more likely to show decreases in functional diversity that exceed those expected from species loss alone. Our results indicate that land-use change non-randomly reshapes the functional structure of vertebrate assemblages, raising concerns about the continuation of ecological processes sustained by vertebrates.

Long-term trends in the phylogenetic and functional diversity of Anatidae in South China coastal wetlands

Species loss has attracted much attention among scientists for more than half a century. However, we have little information on the trends in phylogenetic and functional changes behind the species loss although this information is always asynchronous and important for conservation and management. We measured community trends in Anatidae (ducks and geese) for the last 50 yr to quantify trends in phylogenetic and functional diversity patterns coinciding with taxonomic historical dynamics. We used one-way ANOVAs to test if there was a significant historical trend in communities of Anatidae. We characterized taxonomic, phylogenetic, and functional diversity of communities. For taxonomic diversity, we used species richness (SR). For phylogenetic diversity, we calculated the standardized effect size of mean pairwise distances (ses.MPD) and the standard effect size of mean nearest taxon distances (ses.MNTD) in communities. For functional diversity, we calculated functional richness (FRic), functional evenness (FEve), functional divergence (FDiv), and the community-level weighted means (CWM) of trait values for diet, foraging stratum, and body mass, separately. From the 1950s to 2010s, species richness declined without significant trends. The ses.MNTD of Anatidae communities showed no clear trends. However, ses.MPD of Anatidae communities declined dramatically during this period. For functional diversity, functional evenness of diet, foraging stratum, body mass, and functional dispersion of diet, foraging stratum did not increase or decline significantly. However, functional evenness of all traits, functional richness, and functional dispersion of body mass showed declined trends. The basic phylogenetic diversity and species body mass of Anatidae communities declined significantly because of a declining trend in the relative independent branch of geese. This makes it more challenging for implement community recovery in the future. More attention in conservation biology should consider taxonomic diversity and asynchrony in phylogenetic and functional diversity.

Bird Taxonomic and Functional Diversity in Three Habitats in Buenos Aires City, Argentina

Urban green spaces (UGS), such as parks and wooded streets, are open areas with vegetation that provide sustainability to urban areas. However, their role in conserving bird diversity in neotropical cities has scarcely been analyzed. The aim of this study was to analyze the variation of bird assemblages in non-wooded streets, wooded streets, and parks in Buenos Aires City, Argentina. We compared the taxonomic and functional diversity between these habitat types. We selected five non-wooded streets, five wooded streets, and five parks in the city. Bird surveys were performed in 100 m long and 50 m wide transects. We found that taxonomic diversity had the greatest value in the parks, followed by wooded streets, and then the non-wooded streets. Functional diversity was similar between habitats. The taxonomic and functional composition changed between habitats. Non-wooded streets were dominated by the Rock Dove (Columba livia) and the Eared Dove (Zenaida auriculata), whereas parks had the highest abundance of the Picazuro Pigeon (Patagioenas picazuro) and the Rufous-bellied Thrush (Turdus rufiventris). Non-wooded streets were dominated by omnivorous and granivorous species, whereas parks had a higher abundance of herbivorous and frugivorous species. The positive association between UGS and bird diversity highlights the role of UGS as biodiversity conservation sites in neotropical cities.

Which Traits Influence Bird Survival in the City? A Review

Urbanization poses a major threat to biodiversity worldwide. We focused on birds as a well-studied taxon of interest, in order to review literature on traits that influence responses to urbanization. We review 226 papers that were published between 1979 and 2020, and aggregate information on five major groups of traits that have been widely studied: ecological traits, life history, physiology, behavior and genetic traits. Some robust findings on trait changes in individual species as well as bird communities emerge. A lack of specific food and shelter resources has led to the urban bird community being dominated by generalist species, while specialist species show decline. Urbanized birds differ in the behavioral traits, showing an increase in song frequency and amplitude, and bolder behavior, as compared to rural populations of the same species. Differential food resources and predatory pressure results in changes in life history traits, including prolonged breeding duration, and increases in clutch and brood size to compensate for lower survival. Other species-specific changes include changes in hormonal state, body state, and genetic differences from rural populations. We identify gaps in research, with a paucity of studies in tropical cities and a need for greater examination of traits that influence persistence and success in native vs. introduced populations.

The urban contrast: A nationwide assessment of avian diversity in Mexican cities

In this study we focused on urban bird diversity across Mexico, a megadiverse country, with a special focus on the relative role of urban greenspaces and heavily-built sites. We considered a country-wide approach, including 24 different sized Mexican cities. Our aims were to describe the urban bird diversity in focal cities and further assess the relationships between it and the biogeographic region where cities are located, their size, elevation, and annual rainfall. Additionally, we evaluated differences in the functional composition of bird communities in both studied urban scenarios (i.e., urban greenspaces, heavily-built sites). Our results confirm that urban greenspaces are home to a large proportion of species when contrasted with heavily-built sites. While total species richness and species richness of greenspaces were related with the cities' biogeographic region -with higher species richness in the Neotropical region and Transition Zone-, the relationship did not hold true in heavily-built sites. We found that annual rainfall was negatively related to bird richness in heavily-built sites, suggesting that species from arid systems can be more tolerant to urbanization. Regarding the bird functional group assessment, results show a clear differentiation between the functional groups of greenspaces and those of heavily-built sites, with granivores and omnivores associated with the latter and a highly diverse array of functional groups associated with urban greenspaces.

A Research Agenda for Urban Biodiversity in the Global Extinction Crisis

Rapid urbanization and the global loss of biodiversity necessitate the development of a research agenda that addresses knowledge gaps in urban ecology that will inform policy, management, and conservation. To advance this goal, we present six topics to pursue in urban biodiversity research: the socioeconomic and social–ecological drivers of biodiversity loss versus gain of biodiversity; the response of biodiversity to technological change; biodiversity–ecosystem service relationships; urban areas as refugia for biodiversity; spatiotemporal dynamics of species, community changes, and underlying processes; and ecological networks. We discuss overarching considerations and offer a set of questions to inspire and support urban biodiversity research. In parallel, we advocate for communication and collaboration across many fields and disciplines in order to build capacity for urban biodiversity research, education, and practice. Taken together we note that urban areas will play an important role in addressing the global extinction crisis.

Effects of land use change (rural-urban) on the diversity and epizootiological parameters of avian Haemosporida in a widespread neotropical bird

Transformation of natural environments for livestock, agriculture and human settlements modifies the diversity of organisms, usually decreasing in highly disturbed land uses. Like their hosts, parasites have to adapt to novel human impacted landscapes, in which the abiotic and biotic conditions are radically different from those of conserved natural environments. We evaluated the diversity (alpha and beta taxonomic and phylogenetic diversity) of haemosporidians (mtDNA cyt b lineages) in the common chlorospingus (Chlorospingus flavopectus) at five land use types. We further analyzed the response of prevalence, parasitaemia and parasite aggregation to land use types and seasonality. Parasite lineage richness (i.e., haplotypes) and abundance (no. infected hosts) decreased with disturbance. Parasite assemblages were commonly dominated by either one of two lineages, one dominant in the urban greenspace (pBAEBIC02) and the other dominant in well-preserved mountain cloud forest (hCHLFLA01). Beta diversity was mainly explained by lineage turnover. Phylo beta diversity was low (i.e., lineages are closely related). Overall prevalence increased in wet season that coincides with host's breeding season. Haemoproteus and Plasmodium prevalence presented the opposite response to urbanization (negative and positive, respectively). Parasitaemia presented similar values across land uses for both genera and seasons, while Plasmodium aggregation decreased with urbanization. Thus, some parasite lineages (pBAEBIC02) will benefit from the urbanization process, while others will entirely disappear from cities (hCHLFLA01).

The worldwide impact of urbanisation on avian functional diversity

Urbanisation is driving rapid declines in species richness and abundance worldwide, but the general implications for ecosystem function and services remain poorly understood. Here, we integrate global data on bird communities with comprehensive information on traits associated with ecological processes to show that assemblages in highly urbanised environments have substantially different functional composition and 20% less functional diversity on average than surrounding natural habitats. These changes occur without significant decreases in functional dissimilarity between species; instead, they are caused by a decrease in species richness and abundance evenness, leading to declines in functional redundancy. The reconfiguration and decline of native functional diversity in cities are not compensated by the presence of exotic species but are less severe under moderate levels of urbanisation. Thus, urbanisation has substantial negative impacts on functional diversity, potentially resulting in impaired provision of ecosystem services, but these impacts can be reduced by less intensive urbanisation practices.

Climate and land-use change homogenise terrestrial biodiversity, with consequences for ecosystem functioning and human well-being

Biodiversity continues to decline under the effect of multiple human pressures. We give a brief overview of the main pressures on biodiversity, before focusing on the two that have a predominant effect: land-use and climate change. We discuss how interactions between land-use and climate change in terrestrial systems are likely to have greater impacts than expected when only considering these pressures in isolation. Understanding biodiversity changes is complicated by the fact that such changes are likely to be uneven among different geographic regions and species. We review the evidence for variation in terrestrial biodiversity changes, relating differences among species to key ecological characteristics, and explaining how disproportionate impacts on certain species are leading to a spatial homogenisation of ecological communities. Finally, we explain how the overall losses and homogenisation of biodiversity, and the larger impacts upon certain types of species, are likely to lead to strong negative consequences for the functioning of ecosystems, and consequently for human well-being.