The new corona virus infection SARS-CoV2 which was later renamed COVID-19 is a pandemic affecting public health. The fear and the constraints imposed to control the pandemic may correspondingly ...influence leisure activities, such as birding, which is the practice of observing birds based on visual and acoustic cues. Birders are people who carry out birding observations around the globe and contribute to the massive data collection in citizen science projects. Contrasting to earlier COVID-19 studies, which have concentrated on clinical, pathological, and virological topics, this study focused on the behavioral changes of birders. A total of 4484 questionnaire survey responses from 97 countries were received. The questionnaire had an open-ended style. About 85% of respondents reported that COVID-19 has changed their birding behavior. The most significant change in birdwatchers' behavior was related to the geographic coverage of birding activities, which became more local. People focused mostly on yard birding. In total, 12% of respondents (
= 542 cases) reported having more time for birding, whereas 8% (
= 356 cases) reported having less time for birding. Social interactions decreased since respondents, especially older people, changed their birding behavior toward birding alone or with their spouse. Women reported more often than men that they changed to birding alone or with their spouse, and women also reported more often about canceled fieldtrips or society meetings. Respondents from higher developed countries reported that they spend currently more time for birding, especially for birding alone or with their spouse, and birding at local hotspots. Our study suggests that long lockdowns with strict regulations may severely impact on leisure activities. In addition, a temporal and spatial shift in birding due to the pandemic may influence data quality in citizen science projects. As nature-based recreation will be directed more toward nearby sites, environmental management resources and actions need to be directed to sites that are located near the users, e.g., in urban and suburban areas. The results can be applied with caution to other nature-based recreational activities.
Aim
Urbanization buffers the seasonality of climate conditions and food availability and, therefore, may cause a seasonal homogenization of animal communities. However, the global effect of ...urbanization on the seasonal dynamics of animal communities remains unexplored. Our aim was to study the multi‐continental relationship between urbanization and the seasonal change in bird composition and explore the influence of climatic factors on the urban‐induced reduction of seasonality of bird composition.
Location
Multi‐continental.
Taxon
Birds.
Methods
We performed a literature review and a meta‐analysis. The risk ratio effect size (here referred to as urban seasonality index, USI) was used, considering the number of species seen either in the breeding (spring and/or summer) or the non‐breeding (autumn and/or winter) season, and the number of species seen during both seasons between urban and less urbanized sites. Low USI values indicated a decrease in the seasonal change in bird composition in urban areas. A total of 38 USIs were obtained from 34 cities of six continents.
Results
Multi‐continentally, there are fewer differences in bird composition between seasons in urban than in less urbanized areas, indicating seasonal homogenization due to urbanization. The USI decreased in areas with the lowest maximum temperature and the highest latitude, suggesting the highest decrease in the seasonality of bird composition in urban areas located in regions near the poles and with high seasonal change in temperature. Moreover, studies in the Northern Hemisphere and those that compared suburban versus natural and urban versus rural habitats had a significant decrease in seasonality of bird community in urban areas.
Main conclusions
Urbanization induces a seasonal homogenization of bird composition, and this impact seems more pronounced in temperate areas with broad annual temperature range, and located in the Northern Hemisphere. Results indicate that efforts to restore seasonal dynamics in habitats and resources should be made in urban areas of temperate regions.
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.
•A total of 26 threatened bird species are breeding in European town centers.•Most threatened species are found in only one or a few towns.•Species-rich areas also have many threatened species.•Most ...threatened species nest in cavities or buildings.•Erecting nest boxes, saving old trees and designing buildings suitable for nesting may help these species.
Natural habitats and species richness have decreased due to the urbanization. The main aim of this study was to determine whether heavily urbanized town centers can also harbor threatened bird species. Twenty-six threatened species nested in the most urbanized areas of European towns. Species-rich areas had a high number of threatened species, indicating that overall species richness could be used as a surrogate for the large number of threatened bird species. Threatened species were more likely to be found in town centers as their distribution range increased. Neither landscape nor plot-level variables explained the species richness of threatened species, which was likely due to the homogeneous habitat structure of urban core zone areas in Europe. The occurrence of Falco tinnunculus increased with increases in human density within a built-up area. The occurrence of Hirundo rustica and Muscicapa striata decreased with increases in the proportion of built-up areas in the surrounding landscape. The occurrence of Delichon urbica and Muscicapa striata decreased with increases in habitat diversity and the proportion of buildings in the study plot. The most common threatened bird species nested in cavities or buildings. The availability of suitable nesting sites or protection from predators can support the occurrence of cavity nesters in towns. We suggest that modern architecture should account for the breeding habitat needs of cavity-nesting species in building design and that urban green management must consider the occurrence of old trees with cavities or alternatively use nest boxes to support the occurrence of threatened, cavity-nesting bird species.
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.
Flight initiation distance (FID) is considered a proxy of antipredator behavior. We investigated intraspecific patterns of FID in relation to flock size in gregarious birds. A strong positive relationship between FID and flock size was found.
Current knowledge about the impacts of urbanisation on bird assemblages is based on evidence from studies partly or wholly undertaken in the breeding season. In comparison, the non‐breeding season ...remains little studied, despite the fact that winter conditions at higher latitudes are changing more rapidly than other seasons. During the non‐breeding season, cities may attract or retain bird species because they offer milder conditions or better feeding opportunities than surrounding habitats. However, the range of climatic, ecological and anthropogenic mechanisms shaping different facets of urban bird diversity in the non‐breeding season are poorly understood. We explored these mechanisms using structural equation modelling to assess how urbanisation affects the taxonomic, phylogenetic and functional diversity of avian assemblages sampled worldwide in the non‐breeding season. We found that minimum temperature, elevation, urban area and city age played a critical role in determining taxonomic diversity while a range of factors—including productivity, precipitation, elevation, distance to coasts and rivers, socio‐economic (as a proxy of human facilitation) and road density—each contributed to patterns of phylogenetic and functional diversity. The structure and function of urban bird assemblages appear to be predominantly shaped by temperature, productivity and city age, with effects of these factors differing across seasons. Our results underline the importance of considering multiple hypotheses, including seasonal effects, when evaluating the impacts of urbanisation on biodiversity.
The impact of urbanisation on bird assemblages has mainly been studied in the breeding season, whereas recent climatic conditions have been changing faster in winter, driving a reorganisation of non‐breeding avifauna. We used worldwide surveys conducted in the non‐breeding season to investigate the environmental factors shaping multiple dimensions (taxonomic, phylogenetic, and functional) of urban bird diversity. We found that bird diversity in urban environments is predominantly determined by temperature, productivity and city age, with different effects in the non‐breeding season. Our results suggest that the impacts of urbanisation on biodiversity should be re‐evaluated in the context of seasonality.
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 highdensity 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 landsharing 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.
Patch, matrix and human-induced disturbance variables are important in determining the structure of urban bird communities. Although green spaces in urban core areas are usually small and disturbed, ...they can be important for local bird diversity. Because such areas are often overlooked, their study is critical for successfully incorporating biodiversity conservation in urban planning. Furthermore, comparing bird communities from different biogeographical areas would help identify generalizable patterns and propose common management actions. We compared the structure of breeding season bird assemblages of managed small public green spaces in the urban core areas of two similar-sized European cities, Kavala (Greece) and Rovaniemi (Finland), and studied the influence of environmental variables on community structure. Species composition differed between the cities. Abundance and evenness were higher in Kavala, while richness and diversity did not differ between the cities. Abundance did not respond in a general way to the same variables in the two cities. It increased with decreasing shrub cover and distance from the city center and with increasing midday noise and ground cover in Kavala, but increased with increasing distance from the city center and decreased with increasing car traffic and midday noise in Rovaniemi. This might be explained by the lower abundance of bird dwellers in Rovaniemi. Primarily gray cover, but also other variables, at both the patch and matrix levels (e.g., noise, car traffic, distance from the city center), negatively affected richness, evenness and diversity in both cities. Green space size was positively correlated with richness and diversity in Kavala, but not in Rovaniemi, possibly due to the smaller size variation in Rovaniemi. Results emphasized that increasing gray cover is harmful for birds in small-sized green spaces in urban core areas. However, urban managers should note that not all bird community metrics responded in similar ways to same environmental variables.
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•Small green spaces in urban core areas hold diverse bird communities.•Kavala and Rovaniemi bird communities differed in species composition.•Bird communities differed in abundance and evenness but not richness and diversity.•Urbanization and disturbance factors primarily affected community structure.•Gray cover was the most important negative predictor of structure in both cities.
We studied the homogenisation effects of urbanisation on avifauna in towns of three countries selected along a latitudinal gradient: Italy, France and Finland. In each town (
n
=
19), numbers of ...species were analysed along an urbanisation gradient using two urban sectors (centre and suburban) and one non-urban sector (periurban), representing the regional species pool. Firstly, we compared the avifauna by using species richness and similarity indexes along the urban gradient (S) and latitudinal gradient (L). In Europe, the number of exotic bird species in towns was low. The number of species decreased from the periurban and suburban sectors to the centre sector. Thus, the generally low number of species and few dominant birds indicate that urban bird communities are structurally simple. In addition, many habitat specialists were lacking from urban centres. The centre species represented about 43% of periurban species (similarity S). There was no correlation between town size and species trend in sectors. However, bird community similarity L was lower between town centres than between periurban areas. Latitude explained 89% of the species difference in periurban sector but only 52% in the centre, supporting the homogenisation effect of urbanisation. Secondly, we examined the homogenisation effect through the variability of some specific life-history traits (diets, nest heights, feeding habitats) by using data on Passeriformes. Our results suggested that urbanisation might cause homogenisation by decreasing the abundance of ground nesting bird species and bird species preferring bush-shrub habitats. Urbanisation appeared a cause of taxonomic homogenisation of the avifauna but the effects of latitude and urban habitat diversity may make generalisation difficult.
Urbanization is affecting avian biodiversity across the planet and potentially increasing species vulnerability to climate change. Identifying the resilience of urban bird communities to climate ...change is critical for making conservation decisions. This study explores the pattern in bird communities across nine European cities and examines the projected impact of climate change in order to detect communities facing a higher risk of functional change in the future. First, generalized linear mixed models were used to explore the potential resilience of urban bird communities in nine European cities and the effects of land cover, latitude, abundance of potential predators (dogs and cats), and bird species richness in each trophic guild. Bird community resilience was represented by an index of functional evenness, because it indicates relatively uniform functional space within the species assemblages. Second, bird community resilience in each city was compared with projected changes in temperature and precipitation for the year 2070 to explore potential future threats to conservation. The results showed that community resilience was not significantly associated with land use or abundance of predator. The number of granivorous and granivorous-insectivorous species increases the potential resilience of the community, while the numbers of insectivores, carnivores, and omnivores was negatively correlated with resilience. Of the nine cities, Madrid and Toledo (Spain) are projected to experience the largest change in temperature and precipitation, although their bird communities are characterized by relative high resilience. In contrast, Rovaniemi, at the Arctic Circle (Finland) is projected to experience the second highest increase in temperature among the focused cities, and their bird communities are characterized by low resilience. These findings indicate the importance of future research on the combined effect of functional diversity of species assemblages and climate change on urban biodiversity.
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