An extensive database on the traits and occurrences of amphibian species in Turkey.

Amphibians are the most endangered taxa among vertebrates, and they face many threats during their complex life cycles. The species' life history traits and occurrence database help understand species responses against ecological factors. Consequently, the species-level-trait database has gained more prominence in recent years as a useful tool for understanding the dimensions of communities, assembly processes of communities, and conserving biodiversity at the ecosystem level against environmental changes. However, in Turkey, there are deficiencies in the knowledge of the ecological traits of amphibians compared to other vertebrate taxa, as most studies have focused on their distribution or taxonomic status. Consequently, there is a need to create such a database for future research on all known extant amphibians in Turkey. We compiled a species-level data set of species traits and occurrences for all amphibians in Turkey using 436 literature sources. We completed 36 trait categories with 5611 occurrence data for 37 amphibian species in Turkey. This study provides an open, useful, and comprehensive database for macroecological and conservation studies on amphibians in Turkey.

Dense city centers support less evolutionary unique bird communities than sparser urban areas.

Urbanization alters avian communities, generally lowering the number of species and contemporaneously increasing their functional relatedness, leading to biotic homogenization. Urbanization can also negatively affect the phylogenetic diversity of species assemblages, potentially decreasing their evolutionary distinctiveness. We compare species assemblages in a gradient of building density in seventeen European cities to test whether the evolutionary distinctiveness of communities is shaped by the degree of urbanization. We found a significant decline in the evolutionary uniqueness of avian communities in highly dense urban areas, compared to low and medium-dense areas. Overall, communities from dense city centers supported one million years of evolutionary history less than communities from low-dense urban areas. Such evolutionary homogenization was due to a filtering process of the most evolutionarily unique birds. Metrics related to evolutionary uniqueness have to play a role when assessing the effects of urbanization and can be used to identify local conservation priorities.

Potential hotspots of amphibian roadkill risk in Spain.

We test a forecasting strategy to identify potential hotspots of amphibian roadkill, combining the spatial distribution of amphibians, their relative risk of collision with vehicles and data on road density in Spain. We extracted a large dataset from studies reporting road casualties of 39 European amphibian species and then estimated the 'relative roadkill risk' of species as the frequency of occurrence of casualties for each amphibian and standardized by the range of distribution of the species in Europe. Using a map with the spatial distribution of Spanish amphibians at a spatial resolution of 10 × 10 Km squares, we estimated the 'cumulative relative risk of roadkill' for each amphibian assemblage as the sum of risk estimates previously calculated for each species. We also calculated the total length of roads in each square (road density). Finally, combining all layers of information, we elaborated a forecasting map highlighting the potential amphibian roadkill risk across Spain. Our findings are relevant to suggest areas that should be focused on at more detailed spatial scales. Additionally, we found that the frequency of roadkill was unrelated to the evolutionary distinctiveness score and conservation status of amphibian species, while was positively correlated with their distribution range.

Spatial Overlap and Habitat Selection of Corvid Species in European Cities.

Understanding habitat and spatial overlap in sympatric species of urban areas would aid in predicting species and community modifications in response to global change. Habitat overlap has been widely investigated for specialist species but neglected for generalists living in urban settings. Many corvid species are generalists and are adapted to urban areas. This work aimed to determine the urban habitat requirements and spatial overlap of five corvid species in sixteen European cities during the breeding season. All five studied corvid species had high overlap in their habitat selection while still having particular tendencies. We found three species, the Carrion/Hooded Crow, Rook, and Eurasian Magpie, selected open habitats. The Western Jackdaw avoided areas with bare soil cover, and the Eurasian Jay chose more forested areas. The species with similar habitat selection also had congruent spatial distributions. Our results indicate that although the corvids had some tendencies regarding habitat selection, as generalists, they still tolerated a wide range of urban habitats, which resulted in high overlap in their habitat niches and spatial distributions.

Effects of light and noise pollution on avian communities of European cities are correlated with the species' diet.

Urbanization affects avian community composition in European cities, increasing biotic homogenization. Anthropic pollution (such as light at night and noise) is among the most important drivers shaping bird use in urban areas, where bird species are mainly attracted by urban greenery. In this study, we collected data on 127 breeding bird species at 1349 point counts distributed along a gradient of urbanization in fourteen different European cities. The main aim was to explore the effects of anthropic pollution and city characteristics, on shaping the avian communities, regarding species' diet composition. The green cover of urban areas increased the number of insectivorous and omnivorous bird species, while slightly decreasing the overall diet heterogeneity of the avian communities. The green heterogeneity-a measure of evenness considering the relative coverage of grass, shrubs and trees-was positively correlated with the richness of granivorous, insectivorous, and omnivorous species, increasing the level of diet heterogeneity in the assemblages. Additionally, the effects of light pollution on avian communities were associated with the species' diet. Overall, light pollution negatively affected insectivorous and omnivorous bird species while not affecting granivorous species. The noise pollution, in contrast, was not significantly associated with changes in species assemblages. Our results offer some tips to urban planners, managers, and ecologists, in the challenge of producing more eco-friendly cities for the future.

EVI and NDVI as proxies for multifaceted avian diversity in urban areas.

Most ecological studies use remote sensing to analyze broad-scale biodiversity patterns, focusing mainly on taxonomic diversity in natural landscapes. One of the most important effects of high levels of urbanization is species loss (i.e., biotic homogenization). Therefore, cost-effective and more efficient methods to monitor biological communities' distribution are essential. This study explores whether the Enhanced Vegetation Index (EVI) and the Normalized Difference Vegetation Index (NDVI) can predict multifaceted avian diversity, urban tolerance, and specialization in urban landscapes. We sampled bird communities among 15 European cities and extracted Landsat 30-meter resolution EVI and NDVI values of the pixels within a 50-m buffer of bird sample points using Google Earth Engine (32-day Landsat 8 Collection Tier 1). Mixed models were used to find the best associations of EVI and NDVI, predicting multiple avian diversity facets: Taxonomic diversity, functional diversity, phylogenetic diversity, specialization levels, and urban tolerance. A total of 113 bird species across 15 cities from 10 different European countries were detected. EVI mean was the best predictor for foraging substrate specialization. NDVI mean was the best predictor for most avian diversity facets: taxonomic diversity, functional richness and evenness, phylogenetic diversity, phylogenetic species variability, community evolutionary distinctiveness, urban tolerance, diet foraging behavior, and habitat richness specialists. Finally, EVI and NDVI standard deviation were not the best predictors for any avian diversity facets studied. Our findings expand previous knowledge about EVI and NDVI as surrogates of avian diversity at a continental scale. Considering the European Commission's proposal for a Nature Restoration Law calling for expanding green urban space areas by 2050, we propose NDVI as a proxy of multiple facets of avian diversity to efficiently monitor bird community responses to land use changes in the cities.

Large-scale spatial variability in urban tolerance of birds.

Quantifying intraspecific and interspecific trait variability is critical to our understanding of biogeography, ecology and conservation. But quantifying such variability and understanding the importance of intraspecific and interspecific variability remain challenging. This is especially true of large geographic scales as this is where the differences between intraspecific and interspecific variability are likely to be greatest. Our goal is to address this research gap using broad-scale citizen science data to quantify intraspecific variability and compare it with interspecific variability, using the example of bird responses to urbanization across the continental United States. Using more than 100 million observations, we quantified urban tolerance for 338 species within randomly sampled spatial regions and then calculated the standard deviation of each species' urban tolerance. We found that species' spatial variability in urban tolerance (i.e. standard deviation) was largely explained by the variability of urban cover throughout a species' range (R2  = 0.70). Variability in urban tolerance was greater in species that were more tolerant of urban cover (i.e. the average urban tolerance throughout their range), suggesting that generalist life histories are better suited to adapt to novel anthropogenic environments. Overall, species differences explained most of the variability in urban tolerance across spatial regions. Together, our results indicate that (1) intraspecific variability is largely predicted by local environmental variability in urban cover at a large spatial scale and (2) interspecific variability is greater than intraspecific variability, supporting the common use of mean values (i.e. collapsing observations across a species' range) when assessing species-environment relationships. Further studies, across different taxa, traits and species-environment relationships are needed to test the role of intraspecific variability, but nevertheless, we recommend that when possible, ecologists should avoid using discrete categories to classify species in how they respond to the environment.

Are birds more afraid in urban parks or cemeteries? A Latin American study contrasts with results from Europe.

The escape behaviour, measured as flight initiation distance (FID; the distance at which individuals take flight when approached by a potential predator, usually a human in the study systems), is a measure widely used to study fearfulness and risk-taking in animals. Previous studies have shown significant differences in the escape behaviour of birds inhabiting cemeteries and urban parks in European cities, where birds seem to be shyer in the latter. We collected a regional dataset of the FID of birds inhabiting cemeteries and parks across Latin America in peri-urban, suburban and urban parks and cemeteries. FIDs were recorded for eighty-one bird species. Mean species-specific FIDs ranged from 1.9 to 19.7 m for species with at least two observations (fifty-seven species). Using Bayesian regression modelling and controlling for the phylogenetic relatedness of the FID among bird species and city and country, we found that, in contrast to a recent publication from Europe, birds escape earlier in cemeteries than parks in the studied Latin American cities. FIDs were also significantly shorter in urban areas than in peri-urban areas and in areas with higher human density. Our results indicate that some idiosyncratic patterns in animal fearfulness towards humans may emerge among different geographic regions, highlighting difficulties with scaling up and application of regional findings to other ecosystems and world regions. Such differences could be associated with intrinsic differences between the pool of bird species from temperate European and mostly tropical Latin American cities, characterized by different evolutionary histories, but also with differences in the historical process of urbanization.

Flight initiation distance and refuge in urban birds.

Risk-taking in birds is often measured as the flight initiation distance (FID), the distance at which individuals take flight when approached by a potential predator (typically a human). The ecological factors that affect avian FID have received great attention over the past decades and meta-analyses and comparative analyses have shown that FID is correlated with body mass, flock size, starting distance of the approaching human, density of potential predators, as well as varying along rural to urban gradients. However, surprisingly, only few studies (mainly on reptiles and mammals) have explored effects of different types of refugia and their availability on animal escape decisions. We used Bayesian regression models (controlling for the phylogenetic relatedness of bird species) to explore changes in escape behaviour recorded in European cities in relationship to the birds' distance to the nearest refuge and distance fled to the refuge. In our analyses, we also included information on the type of refuge, built-up and vegetation cover, starting distance, flock size, urbanization level, and type of urban habitat. We found that birds preferred tree refuges over artificial and bush refuges. Birds escaped earlier if the distance to the nearest refuge of any type was longer and if birds fled longer distances to the refuge. FID was shorter when birds used bushes as refugia or landed on the ground after flushing compared to using artificial refugia. Similarly, the distance fled to a refuge was shortest when using bushes, and increased when escaping to artificial substrates and trees. Birds were more timid in suburban than core areas of cities, cemeteries than parks, and in areas with higher bush cover but lower cover of built-up areas and trees. Our findings provide novel information regarding the importance of refuge proximity and type as factors affecting the escape behaviour of urban birds.

Resident birds are more behaviourally plastic than migrants.

Species subjected to more variable environments should have greater phenotypic plasticity than those that are more restricted to specific habitat types leading to the expectation that migratory birds should be relatively more plastic than resident birds. We tested this comparatively by studying variation in flight initiation distance (FID), a well-studied antipredator behaviour. We predicted that variation in FID would be greater for migratory species because they encountered a variety of locations during their lives and therefore had less predictable assessments of risk compared to more sedentary species. Contrary to our prediction, we found that non-migratory species (sedentary) had greater variation in FID than migratory ones. Migratory and partially migratory birds had greater average FIDs than sedentary birds, suggesting that they were generally more wary. These results suggest that the predictability associated with not migrating permits more nuanced risk assessment which was seen in the greater variation in FID of sedentary bird species.

Spatial Distribution and Habitat Overlap of Five Columbidae Species in the Czech Republic.

Habitat overlap occurs when two species co-exist in the same habitat and utilise the same resources. Using common bird monitoring data in Czech Republic from 2015 and 2016, we compared the affinities of five Columbidae species regarding land use types. Moreover, we analysed the effects of land use types and land use heterogeneity on five species distributions. The aim of the study was to quantify the habitat overlap of five Columbidae species regarding types of land use and land use heterogeneity. We predicted a high level of habitat overlap between most of the species and its occurrence in farmlands and urban areas. Our results confirmed the high habitat overlap of all five Columbidae species in farmlands. An almost complete overlap was recorded between Columba livia domestica and Streptopelia decaocto, as well as between Columba palumbus and Streptopelia turtur. Considering land use utilisation, C. livia and S. decaocto mainly utilised farmlands and urban areas. Furthermore, deciduous forests were utilised by Columba oenas and coniferous and mixed forests by C. palumbus. Finally, S. turtur mainly utilised grasslands and avoided urban areas. We conclude that Columbidae species overlap in spatial distributions, mostly in urban areas, forests, and farmlands. Our study provides a summary of these common species habitat affinities.

Effects of urbanization on taxonomic, functional and phylogenetic avian diversity in Europe.

Europe is an urbanized continent characterized by a long history of human-wildlife interactions. This study aimed to assess the effects of specific elements of urbanization and urban pollution on complementary avian diversity metrics, to provide new insights on the conservation of urban birds. Our study recorded 133 bird species at 1624 point counts uniformly distributed in seventeen different European cities. Our results thus covered a large spatial scale, confirming both effects of geographical and local attributes of the cities on avian diversity. However, we found contrasting effects for the different diversity components analyzed. Overall, taxonomic diversity (bird species richness), phylogenetic diversity and relatedness were significantly and negatively associated with latitude, while functional dispersion of communities showed no association whatsoever. At the local level (within the city), we found that urban greenery (grass, bush, and trees) is positively correlated with the number of breeding bird species, while the building cover showed a detrimental effect. Functional dispersion was the less affected diversity metric, while grass and trees and water (rivers or urban streams) positively affected the phylogenetic diversity of avian communities. Finally, the phylogenetic relatedness of species increased with all the main indicators of urbanization (building surface, floors, pedestrian's density and level of light pollution) and was only mitigated by the presence of bushes. We argue that maintaining adequate levels of avian diversity within the urban settlements can help to increase the potential resilience of urban ecosystems exposed to the stress provoked by rapid and continuous changes. We listed some characteristics of the cities providing positive and negative effects on each facet of urban avian diversity.

Sacred oak woods increase bird diversity and specialization: Links with the European Biodiversity Strategy for 2030.

Sacred groves in Greece are usually forest remnants with large trees around chapels, protected through centuries by Orthodox religion. We examined the comparative ecological value of 20 oak-dominated sacred groves vs managed oakwoods, in terms of their habitat characteristics and avian communities (passerines and woodpeckers). Sacred groves have maintained a more pronounced old-growth character than managed oakwoods in terms of average Diameter at Breast Height (DBH) and tree height. Besides holding significantly greater bird species richness and abundance, they supported greater functional richness, phylogenetic diversity, and phylogenetic bird species variability. Bird communities in sacred groves were more heterogeneous and showed greater avian specialization levels than in managed woods. Generalized Linear Models showed that the main factor positively affecting all aspects of bird diversity was DBH, while the abundance of dead trees increased bird abundance. Our results underline the importance of maintaining large-sized trees in forest management practices to support bird diversity and decrease biotic homogenization. Since the new European Biodiversity Strategy explicitly requires all remaining European primary and old-growth forests to be strictly protected by 2030, we argue that sacred groves, despite their small size, meet the criteria to be considered in the strict protection and restoration targets of the strategy, as primary old growth woods of high biodiversity value.

Eiders, nutrients and eagles: Bottom-up and top-down population dynamics in a marine bird.

The main objective of this long-term study (1978-2016) was to find the underlying factors behind the declining trends of eider Somateria mollissima in the Baltic/Wadden Sea. Specifically, we aimed at quantifying the bottom-up effect of nutrients, through mussel stocks, on reproduction and abundance of eider, and the top-down effects caused by white-tailed eagle Haliaeetus albicilla predation. Bottom-up effects increase marine primary productivity with subsequent effects on food availability for a major mussel predator. Top-down effects may also regulate eider populations because during incubation female eiders are vulnerable to predation by eagles. Our structural equation modelling explained a large percentage of the variance in eider abundance. We conclude that the Baltic/Wadden Sea eider population was regulated directly by white-tailed sea eagle predation on incubating females and indirectly by the amount of nutrients in seawater affecting both mussel stocks and the breeding success of eiders, reflecting density dependence. These findings may explain the decreasing trend in the Baltic/Wadden Sea eider population during the last decades as an additive effect of top-down and bottom-up factors, and likely as an interaction between them.

Diet specialization and brood parasitism in cuckoo species.

Brood parasitism is a breeding strategy adopted by many species of cuckoos across the world. This breeding strategy influences the evolution of life histories of brood parasite species.In this study, we tested whether the degree on diet specialization is related to the breeding strategy in cuckoo species, by comparing brood parasite and nonparasite species. We measured the gradient of diet specialization of cuckoos, by calculating the Gini coefficient, an index of inequality, on the multiple traits describing the diet of species. The Gini coefficient is a measure of statistical dispersion on a scale between 0 and 1, reflecting a gradient from low to high specialization, respectively. First, we tested the strength of the phylogenetic signal of diet specialization index among cuckoo species worldwide. Then, we ran phylogenetic generalized least square (PGLS) models to compare diet specialization, distribution range, and body mass of parasitic and nonparasitic cuckoo species, considering the phylogenetic signal of data.After adjusting for the phylogenetic signal of the data and considering both, species distribution range and species body mass, brood parasitic cuckoos were characterized by higher diet specialization than nonbrood parasitic species. Brood parasitic species were also characterized by a larger breeding distribution range than nonparasitic species.The findings of this study provide an additional understanding of the cuckoos' ecology, relating diet and breeding strategies, information that could be important in conservation ecology.

Biodiversity within the city: Effects of land sharing and land sparing urban development on avian diversity.

Urbanization, one of the most extreme human-induced environmental changes, is negatively affecting biodiversity worldwide, strongly suggesting that we should reconcile urban development with conservation. Urbanization can follow two extreme types of development within a continuum: land sharing (buildings mixed with dispersed green space) or land sparing (buildings interspersed with green patches that concentrate biodiversity-supporting vegetation). Recent local-scale studies indicate that biodiversity is typically favored by land sparing. We investigated which of these two types of urbanization is associated with a higher taxonomic (i.e. species richness), functional, and phylogenetic diversity of birds. To do so, we collected information on breeding and wintering bird assemblages in 45 land-sharing and 45 land-sparing areas in nine European cities, which provide the first attempt to explore this question using a large geographical scale and temporal replication. We found that land-sharing urban areas were significantly associated with a higher taxonomic and functional diversity of birds during winter, but not during the breeding season (with only a marginally significant effect for functional diversity). We found no association between the type of urban development and phylogenetic diversity. Our findings indicate that not all components of avian diversity are similarly affected by these two means of urban planning and highlight the importance of integrating the temporal perspective into this kind of studies. Our results also offer useful information to the current debate about the trade-off between biodiversity conservation and human well-being in the context of land sharing and sparing urban practices. In addition, we found that certain small-scale urban landscape characteristics (i.e. few impervious surfaces, high water or tree cover) and human practices (i.e. bird feeders or plants with berries) can help maintaining more diverse urban bird assemblages. We provide specific suggestions for both policymakers and citizens that hopefully will help to create more biodiversity-friendly cities in the future.

Land-sharing vs. land-sparing urban development modulate predator-prey interactions in Europe.

Urban areas are expanding globally as a consequence of human population increases, with overall negative effects on biodiversity. To prevent the further loss of biodiversity, it is urgent to understand the mechanisms behind this loss to develop evidence-based sustainable solutions to preserve biodiversity in urban landscapes. The two extreme urban development types along a continuum, land-sparing (large, continuous green areas and high-density housing) and land-sharing (small, fragmented green areas and low-density housing) have been the recent focus of debates regarding the pattern of urban development. However, in this context, there is no information on the mechanisms behind the observed biodiversity changes. One of the main mechanisms proposed to explain urban biodiversity loss is the alteration of predator-prey interactions. Using ground-nesting birds as a model system and data from nine European cities, we experimentally tested the effects of these two extreme urban development types on artificial ground nest survival and whether nest survival correlates with the local abundance of ground-nesting birds and their nest predators. Nest survival (n = 554) was lower in land-sharing than in land-sparing urban areas. Nest survival decreased with increasing numbers of local predators (cats and corvids) and with nest visibility. Correspondingly, relative abundance of ground-nesting birds was greater in land-sparing than in land-sharing urban areas, though overall bird species richness was unaffected by the pattern of urban development. We provide the first evidence that predator-prey interactions differ between the two extreme urban development types. Changing interactions may explain the higher proportion of ground-nesting birds in land-sparing areas, and suggest a limitation of the land-sharing model. Nest predator control and the provision of more green-covered urban habitats may also improve conservation of sensitive birds in cities. Our findings provide information on how to further expand our cities without severe loss of urban-sensitive species and give support for land-sparing over land-sharing urban development.

Measuring avian specialization.

Measuring the extent to which a species is specialized is a major challenge in ecology, with important repercussions for fundamental research as well as for applied ecology and conservation. Here, we develop a multidimensional index of specialization based on five sets of ecological characteristics of breeding bird species. We used two recent databases of species traits of European birds based on foraging ecology, habitat, and breeding characteristics. The indices of specialization were calculated by applying the Gini coefficient, an index of inequality. The Gini coefficient is a measure of statistical dispersion on a scale between 0 and 1, reflecting a gradient from low to high specialization, respectively. Finally, we tested the strength of the phylogenetic signal of each specialization index to understand how the variance of such indices is shared throughout the phylogeny. The methods for constructing and evaluating a multidimensional index of bird specialization could also be applied to other taxa and regions, offering a simple but useful tool, particularly suited for global or biogeographic studies, as a contribution to comparative estimates of the degree of specialization of species.

Contagious fear: Escape behavior increases with flock size in European gregarious birds.

Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator-prey interactions. Among the factors affecting FID, tests of effects of group size (i.e., number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e., the dilution effect caused by the presence of many individuals) or positively (i.e., increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than nongregarious species. Sociality may explain why earlier findings on group size versus FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude, and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer FID) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of antipredator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species.

Number of syllables in cuckoo Cuculus canorus calls: A test using a citizen science project.

Recent studies revealed that the call of the common cuckoo Cuculus canorus has more inter-individual than intra-individual variation and that the number of syllables depends on environmental conditions, but also the presence of male and female conspecifics. However, still very little is known about how song varies at a global scale, especially considering the wide distribution of this species across most of Europe and Asia. Xeno-canto.org is a vocalization repository for birdsong. We used xeno-canto.org as a data source for investigating the variables that affect the number of syllables in cuckoo calls at a large spatial scale. At a very broad geographical scale, the number of syllables in cuckoo calls predicted bird species richness. Additionally, female calls were associated with shorter males calls, and there was a positive correlation between the interaction between female calls and the number of host races parasitized by the cuckoo. These findings confirm that intraspecific and interspecific interactions significantly affect the number of syllables in cuckoo calls, and both environmental variables and biotic interactions should be considered in future studies of vocalizations in cuckoos. Last but not least, we demonstrated that a citizen science project is a useful source for ecological studies at large spatial scales.