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.
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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•Bird species composition in urban communities across 15 European cities were recorded.•Some areas were classified as high environmental quality – HEQ urban areas.•HEQ areas have high ...green cover/diversity, low light pollution and high avian resilience.•Multiple bird species were found as indicators of HEQ urban areas, depending on the city.•The top ranked birds HEQ-indicator were Eurasian blackcap, Blackbird and Great tit.
Urban and suburban areas are among the fastest-growing land-use types globally, reducing and fragmenting natural habitats for many animal species and making human-wildlife interactions more common. However, cities also create habitat for several species considered urban tolerant or urban exploiter species. Additionally, the environmental characteristics of urban areas can strongly affect the life quality of citizens. This study aimed to assess the effectiveness of common bird species as indicators of urban areas with high environmental quality within cities. Our study recorded 128 bird species in 1441 point counts distributed in fifteen different European cities. We classified urban areas as “high environmental quality” – HEQ when they were simultaneously characterized by a high vegetation cover and heterogeneity, low level of light pollution, and avian communities with high potential resilience to face ecological stress. Species indicators of HEQ urban areas were identified using the species-level indicator value (IndVal) analysis. Such species can be used as ecological indicators of HEQ in different European cities. The list of top ten birds indicators of HEQ in European cities is led by the Eurasian blackcap, selected as an indicator in more than half of the survey cities. Other birds indicators of HEQ in multiple cities are Blackbird (47%), Great tit (40%), Blue tit, Tree sparrow and Magpie (all 33%). The mean specificity of the top-ranked bird indicator of HEQ urban areas (Eurasian blackcap) was 0.778. Most of the HEQ-indicators are resident or resident/short migratory species characterized by territorial behaviour. Our findings support using multiple species as bioindicators of urban changes by using specific groups with few common species as surrogates of HEQ urban areas. The approach proposed in this study can be applied in different European cities to monitor biodiversity status periodically, even involving citizen science initiatives.
All animals flee from potential predators, and the distance at which this happens is optimized so the benefits from staying are balanced against the costs of flight. Because predator diversity and ...abundance decreases with increasing latitude, and differs between rural and urban areas, we should expect escape distance when a predator approached the individual to decrease with latitude and depend on urbanization. We measured the distance at which individual birds fled (flight initiation distance, FID, which represents a reliable and previously validated surrogate measure of response to predation risk) following a standardized protocol in nine pairs of rural and urban sites along a ca. 3000 km gradient from Southern Spain to Northern Finland during the breeding seasons 2009-2010. Raptor abundance was estimated by means of standard point counts at the same sites where FID information was recorded. Data on body mass and phylogenetic relationships among bird species sampled were extracted from the literature. An analysis of 12,495 flight distances of 714 populations of 159 species showed that mean FID decreased with increasing latitude after accounting for body size and phylogenetic effects. This decrease was paralleled by a similar cline in an index of the abundance of raptors. Urban populations had consistently shorter FIDs, supporting previous findings. The difference between rural and urban habitats decreased with increasing latitude, also paralleling raptor abundance trends. Overall, the latitudinal gradient in bird fear was explained by raptor abundance gradients, with additional small effects of latitude and intermediate effects of habitat. This study provides the first empirical documentation of a latitudinal trend in anti-predator behavior, which correlated positively with a similar trend in the abundance of predators.
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.
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.
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•Avian taxonomic and functional diversity is higher in land-sharing urban areas.•This effect is found in winter but not in the breeding season.•Not all components of avian biodiversity are affected similarly by urban planning.•Few impervious surfaces and high water or tree cover promote avian urban diversity.•Bird feeders and plants with berries promote more diverse urban bird assemblages.
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.
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•Flight initiation distance (FID) is considered a proxy of antipredator behaviour.•We investigated changes in FID of birds in relation to refuge type and availability.•We found that birds preferred tree refuges over artificial and bush refuges.•Birds escaped earlier if the distance to the nearest available refuge was longer.•Birds fled longer distances to the refuge when were more afraid (with longer FID).
Life-history theory predicts that current behaviour affects future reproduction, implying that animals should optimise their escape strategies to reflect fitness costs and benefits of premature ...escape. Both costs and benefits of escape may change temporally with important consequences for the evolution of escape strategies. Moreover, escape strategies of species may differ according to their positions on slow-fast pace of life gradients. We studied risk-taking in long-distance migratory animals, waders (Charadriiformes), during the annual cycle, i.e., breeding in Europe, stopover in the Middle East and wintering in tropical Africa. Phylogenetically informed comparative analyses revealed that risk-taking (measured as flight initiation distance, FID) changed significantly over the year, being lowest during breeding and peaking at stopover sites. Similarly, relationships between risk-taking and life-history traits changed among stages of the annual cycle. While risk-taking significantly decreased with increasing body mass during breeding, risk-taking-body mass relationship became marginally significant in winter and disappeared during migration. The positive trend of risk-taking along slow-fast pace of life gradient measured as adult survival was only found during breeding. The season-dependent relationships between risk-taking and life history traits suggest that migrating animals respond to fluctuating environments by adopting behavioural plasticity.
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.
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.
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•Four measures of avian diversity were estimated in bird communities of European cities.•Taxonomic and phylogenetic avian diversity were negatively associated with latitude.•Urban greenery increased avian taxonomic diversity, while building decreased it.•Grass, trees, and water positively affected phylogenetic diversity of avian communities.•Phylogenetic relatedness increased with urbanization and was only mitigated by bushes.
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