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Ecology and Conservation of Birds in Urban Environments

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Summarizes the current research on the interplay between urban environments and bird fauna ▶ Provides a conservation-based approach, paying special attention to issues like bird monitoring and managing of bird populations, and the incardination of the design and management of urban green spaces in urban planning policies ▶ Includes examples coming from different parts of the world in an effort to obtain a thorough perspective This book provides syntheses of ecological theories and overarching patterns of urban bird ecology that have only recently become available. The numerous habitats represented in this book ranges from rows of trees in wooded alleys, to wastelands and remnants of natural habitats encapsulated in the urban matrix. Authored by leading scientists in this emergent field, the chapters explore how the characteristics of the habitat in urban environments influence bird communities and populations at multiple levels of ecological organization and at different spatial and temporal scales, and how this information should be incorporated in urban planning to achieve an effective conservation of bird fauna in urban environments. Birds are among the most conspicuous and fascinating residents of urban neighborhoods and provide urban citizens with everyday wildlife contact all over the world. However, present urbanization trends are rapidly depleting their habitats, and thus knowledge of urban bird ecology is urgently needed if birds are to thrive in cities. The book is unique in its inclusion of examples from all continents (except Antarctica) in an effort to arrive at a more holistic perspective. Among other issues, the individual chapters address the censusing of birds in urban green spaces; the relationship between bird communities and the structure of urban green spaces; the role of exotic plant species as food sources for urban bird fauna; the influence of artificial light and pollutants on bird fauna; trends in long-term urban bird research, and transdisciplinary studies on bird sounds and their effects on humans. Several chapters investigate how our current knowledge of the ecology of urban bird fauna should be applied in order to achieve better management of urban habitats so as to achieve conservation of species or even increase species diversity. The book also provides a forward-looking summary on potential research directions. As such, it provides a valuable resource for urban ecologists, urban ecology students, landscape architects, city planners, decision makers and anyone with an interest in urban ornithology and bird conservation. Moreover, it provides a comprehensive overview for researchers in the fields of ecology and conservation of urban bird fauna.
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Chapters (24)

More than half of the world’s human population lives in cities in which birds constitute the major, or only, contact people have with wildlife. The vast amount of predicted urbanization in the coming years will, however, consume habitats and reduce the possibilities for birds to thrive in cities and thus also reduce people’s potential to detect birds. The scientific literature is presently dominated by studies from Europe and North America although the largest occurring urbanization processes occur in South East Asia and Africa. Further, these understudied continents, together with South America, harbor some of the most important areas of urban bird biodiversity and are thus of special importance to study. The last 15 years of urban bird ecology research have been exponential and now enables amalgamations and reviews of research. Here, in this volume, we try to overview these present findings in urban bird research from all continents. We illustrate this by overviewing patterns and processes, spatial and temporal scales and methodological approaches, pollution effects on birds, bird’s effects on human well-being, and how urban habitats are conserved and managed for birds. The patterns of how urban birds are affected by urbanization processes are similar globally, with decreasing habitats and change of habitat qualities and pollution effects. However, increasing number of areas for urban bird conservation are being recognized and habitats managed to provide urban bird populations are increasing. In a global perspective, cities do still provide habitats to allow a diverse bird fauna.
The rapid urbanization of the world has profound effects on global biodiversity, and urbanization has been counted among the processes contributing to the homogenization of the world’s biota. However, there are few generalities of the patterns and drivers of urban birds and even fewer global comparative studies. Comparable methodologies and datasets are needed to understand, preserve, and monitor biodiversity in cities. We explore the current state of the science in terms of basic patterns of urban birds in the world’s cities and lay out a research agenda to improve basic understanding of patterns and processes and to better inform conservation efforts. Urban avifaunas are often portrayed as being species poor and dominated by omnivorous and granivorous species that tend to be nonnative. Common families in cities include Accipitridae, Anatidae, and Scolopacidae, all of which have more species than expected in cities compared to the global distribution of species in these families. Recent research shows that cities support an avifauna dominated by native species and that cities are not homogenized at the global level. However, cities have lost substantial biodiversity compared to predicted peri-urban diversity, and 31 of the world’s most invasive bird species are found in cities. Future research is needed to better characterize the anthropogenic, environmental, and ecological drivers of birds in cities. Such mechanistic understanding is the underpinning of effective conservation strategies in a human dominated world.
Urbanization is an expanding process worldwide, and South America seems to follow the general pattern observed in more urbanized regions of the world. Most conceptual models on the response of biodiversity to urbanization, however, are based on the experience in developed economies. In this chapter, we summarize patterns of bird communities found at different spatial and temporal scales in southern South America. Along a 1,400-km latitudinal gradient we found that urbanization: 1) obscured the latitudinal pattern of bird species richness, 2) had a stronger negative effect on bird richness in tropical than in temperate or arid regions, and 3) resulted in more similar communities than the seminatural or rural areas, suggesting a process of biotic homogenization. The analysis of urban centers of different sizes indicated that bird richness and abundance were negatively affected by urbanization only in cities above 7,000 and 13,000 inhabitants, respectively. In the Pampean region, urbanization affected negatively birds that nest on the ground, with insectivorous and carnivorous diets, feeding on the air and on vegetation and with solitary and migratory behaviors. Urbanization decreased the seasonal and interannual variability of bird species composition. We suggest future directions of research on the influence of latitude on temporal dynamics of bird communities in urban areas, comparison of bird responses to urbanization among biogeographical regions using a mechanistic approach, and including functional and phylogenetic diversity as response variables in the analyses.
China has been experiencing remarkable urban expansion in recent decades. The rapid urbanization progress also drew much attention of researchers on urban birds and the effect of urbanization on birds. We summarized the papers on urban birds in China published from 1962 to 2014. To understand the urban bird diversities in China, we selected 17 cities across different bioregions even biogeographical realms whose bird diversities had been carefully surveyed and chose ten most abundant resident birds representing the urban birds of the cities. We measured the phylogenetic structure and the family diversity of ten species of each city and then examined their variations with the city’s population, latitude, and longitude. The results showed that 49 species dwell in the 17 cities as the top 10 abundant birds which cover three orders and 20 families. Crows, starlings, tits, and bulbuls are the most abundant species in the urban areas in China. The cities, on the one hand, close in geography have close bird lists which implied that local fauna has important impacts on urban bird assemblages. On the other hand, some cities far apart also share close bird lists probably due to the process of homogenization of urbanization. The cities with higher latitudes usually support birds more discretely in phylogenetic structure, but with lower family diversity. We also reviewed the urbanization effects on the birds. Evidences showed significant patterns of birds in response to urbanization in China at community, species, and even individual levels.
Many nonindigenous organisms, including birds, are often restricted to human-altered environments within the region of introduction. The classical explanation is that human-related alterations make the environment easier to invade by reducing biotic resistance and offering new niche opportunities. However, the pattern may also reflect that many more species have been introduced in human-altered environments and/or that traits associated with invasion success and the ability to thrive in these environments are related. In this chapter, we argue that if we want to fully understand why exotic organisms are mainly successful in human-altered environments, we need to see the invasion process as a set of stages with different probabilities of being transited. Applied to birds, this framework suggests that there is a high probability that an exotic species ends up associated with human-altered environments if the species: (1) is more abundant (and hence more available for introduction) in urbanized environments; (2) has a higher chance to be successfully transported, as it is already habituated to humans; and (3) has a higher probability to be introduced in an urbanized environment, where most humans live. If these arguments are true, then the exotic species is likely to successfully establish itself in the new region because the species should already have the traits needed to persist in the novel environment. Although more supporting evidence is needed, the proposed framework provides a general solution for the paradox that many invaders are more successful in the new environment than most native species.
Although cities have existed for some millennia, it has been only in the last few centuries that they have expanded to become a dominant feature of the landscape. Their growth displaces original habitats and creates new ones, facing birds with the challenge of adjusting their behaviour, physiology and life histories to the novel conditions or be displaced into a shrinking and also increasingly altered rural landscape. Here we identify the salient features—habitat structure, seasonality, interspecific interactions and pollution—in which cities differ from natural environments and to which birds must adjust. Then we describe the several ways in which urban birds have been found to differ from their rural counterparts. Finally, we evaluate whether these differences constitute adaptations to urban conditions or whether they are expressions of pre-existing adaptations to natural conditions, such as behavioural plasticity, which also permit the colonisation of urban habitats.
A key question in evolutionary behavioural ecology is how species cope with changes in their environments. In the last centuries, humans have caused dramatic changes in our planet that have affected the way many animals behave. In order to live in cities, most animals are forced to adjust their behaviour and life histories to the new urban habitat. While growing evidence reports behavioural differences between rural and urban conspecifics as common and cross-taxonomical, the mechanisms underlying such differences in behaviour remain largely unknown. Recent research using animals with limited experience of their natural urban or rural environments points to the existence of intrinsic differences in behaviour between rural and urban conspecifics. This suggests that phenotypic plasticity might not be the only mechanism explaining behavioural differences between rural and urban individuals and that differences in individually consistent behavioural traits could also be the result of microevolution in the urban environment. Knowing that urbanization is and will continue to be a major environmental challenge to most living organisms, it is urgent to understand the mechanisms allowing animals to cope with our urbanizing world. In this chapter, I focus on the existence of different behavioural phenotypes between rural and urban animals and on the possible mechanisms leading to such behavioural differences.
The composition of urban bird communities is clearly affected by local habitat factors. These factors often determine whether individuals choose to occupy urban habitats and how they behave and reproduce once they are there. However, landscape-scale factors also play a major role in the shaping of urban bird communities. Most commonly, these are elements of the landscape for which heterogeneity can be meaningfully measured at scales of 500–2500 m. The influence of landscape-scale factors is studied using two approaches—the island biogeography approach and the urbanization gradient approach. Commonly influential factors include the remnant habitat patch size, degree of urbanization, road density, amount of tree or paved area cover and land use (a proxy for human disturbance). While there are no consistent patterns governing the responses of overall species diversity and community composition to landscape-scale factors, when species are grouped by life history guilds, consistent patterns emerge. When considered in conjunction with local habitat factors, research about the effects of landscape-scale factors provides valuable implications for the conservation of avian biodiversity in urban environments, especially when specific species and guilds are the targets of conservation efforts.
The vast majority of urban bird research is conducted over relatively short time frames (1–2 years), thereby limiting our ability to understand how temporal processes influence urban bird populations and communities. To further evaluate the importance of and contributions provided by long-term (≥5 years) ecological studies of urban avifauna, we reviewed the published literature for such studies to (1) explore and characterize the focus of long-term urban bird research, (2) identify gaps in our knowledge base, and (3) make suggestions for future research. We identified 85 papers published between 1952 and 2014 for this review. While long-term studies ranged from 5 to 175 years, most were ≤30 years in length. Community-level studies predominately quantified how urbanization affects species richness and composition through time, while population-level studies were primarily on single species of larger body size (≥80 g). Almost every study we reviewed was conducted in North America and Europe, a result that is generally unsurprising as temperate zones and wealthier countries are overrepresented in the literature. Overall, long-term studies provide unique insights into how slow and subtle processes, land-use legacies, time-lagged responses, and complex phenomena influence urban birds. To better encourage the inclusion of long-term studies in urban avian ecology, we suggest that ecologists should (1) keep long-term phenomena in mind when constructing short-term studies, (2) make published datasets accessible, and (3) provide adequate metadata regarding how data was collected.
Counts of birds can inform studies with different goals, such as estimating population size, monitoring populations over time and in response to environmental change, and estimating vital rates to model population dynamics. Because estimates need to be reasonably accurate and precise, considerable thought has gone into developing counting techniques that enable robust estimation of abundance, taking into account probability of detection, which can vary between species, land cover types and over time. In recent years these have been applied to over 60 % of studies estimating bird abundance conducted in non-urban landscapes. However, robust estimation techniques are not being similarly applied to studies in urban areas. We reviewed 162 articles in which birds had been counted and abundance and/or occupancy reported in urban areas, spanning the years 1991 to 2015, and found that only 11 % attempted to account for variable detectability; few of these had modelled detectability satisfactorily. There was no indication of increasing methodological rigour over time. Counting birds in urban areas poses significant challenges; robust techniques are constrained by limitations imposed by built structures, social factors and a mosaic of many small private parcels of land. We present a framework for estimating bird abundance and discuss the strengths and weaknesses of the different approaches, relating each to the urban context. Citizen science initiatives are considered as a good fit in urban areas and are increasing in number: sampling designed for all landscapes might be inappropriate in urban areas, but counting protocols should allow the modelling of detection probability.
For half a century regarded as the most appropriate methodological approach for censusing wild animals and plants, the atlases are also used for presenting the distribution of avifauna in European towns and cities. This chapter looks at ornithological atlases concerning solely an urban area and not in a much more extensive region of which that area is just a small part. To date (2014) at least 77 avifauna atlases have been published for 66 towns and cities in Europe. In Italy (44 atlases), Poland (12) and Germany (8), this is currently the usual way of describing the distribution of bird species within an entire urban area. The cartographic basis for presenting the material is usually a grid of cells based on Universal Transverse Mercator (UTM) or some other system like the Gauss-Krüger. Less commonly, the grid is defined by geographic coordinates, and, exceptionally, a mosaic of irregularly shaped plots may be used, as in the Turin and Warsaw atlases. The majority of atlases relate exclusively to breeding birds, the maps showing the probability of breeding and/or the number of breeding in the grid cells. Only a few urban atlases supply cartographic information on wintering birds or their year-round status. Repeat editions of atlases include maps comparing present and past distributions. For most cases each atlas cell was surveyed ca four times per season. The fieldwork usually lasted 1–2 years in small towns but from 3 to 10 years in larger ones. The number of observers was often independent of the size of the area to be surveyed: in some cases up to a dozen or so experienced ornithologists were involved, but usually a large number (50–60 to over 100) volunteers took part. Compared with traditional verbal descriptions, an atlas mapping the distribution of birds in an urban area is of greater use as a scientific document, as a source of data for urban planning and for popularising wildlife among its inhabitants. It ensures better coverage of the area, comparability and transparency of the data and is more useful for municipal administration purposes.
Industrialization, traffic, intensification of agriculture, and development of human lifestyle in general during the last century have resulted in elevated levels of various chemical compounds in our environment. Especially in urbanized areas, harmful substances are produced in such quantities that they can have a deleterious effect on the development, survival, and reproduction of organisms. Many bird species have adapted to living alongside with humans and even discovered new resources within the urban lifestyle. However, these birds are in greatest risk of being harmfully effected by various chemicals. This chapter reviews the effects of heavy metals and organic pollutants on avian populations in urban areas. Case studies are brought together in order to gain comprehension on how well we understand the role of these pollutants as factor influencing the well-being of urban bird populations. The examples highlight the fact that pollutants do not have only direct physiological effects but also indirect effects through, e.g., decreased food availability. As populations of many urban bird species are declining, new research developments for pollution studies are also proposed.
Light pollution has become an important theme of both scientific research and policy-making. Although in recent years we have seen a boost of research on this topic, there is still surprisingly little knowledge on the levels of artificial light at night that wild animals really experience. I made use of miniature light loggers attached to individual free-living European blackbirds (Turdus merula) to measure the light intensity to which these birds are exposed to in forest and urban areas. I have first shown that male blackbirds living in a city are indeed exposed to higher levels of light at night compared to forest conspecifics, but these levels are substantially lower to what can be measured underneath typical street lamps. Recently I have offered new perspectives by estimating the subjective day length to which urban and rural blackbirds are exposed to and by analysing the overall light intensity to which blackbirds are exposed daily. In a series of studies, I have interpreted these data in the context of daily patterns of activity as well as seasonal biology. European blackbirds which were exposed to a longer photoperiod than their rural counterparts extended their activity into the night and showed reduced levels of melatonin production in the early morning, suggesting that this could be the biophysical process underlying the early onset of daily activity, but also the advanced breeding season observed in many avian species that successfully colonize urban areas. Indeed, I found a remarkable similarity between the difference in the photoperiod experienced by rural and urban blackbirds and the difference in timing of reproduction and onset of daily activity between my two study populations. I will discuss these findings and underlie several outstanding questions that still remain unresolved.
A common generalization is that wild birds somehow manage to colonize urban areas without human support, which is often true. This paper focuses on a different and probable, though not rare, course of events, when some urban bird populations emerge with immediate human support, by intentional introductions or escape from captivity. This alternate mechanism may be responsible for settling the very first colonizers directly into a strongly urbanized habitat. Such “pioneers” might later be followed by “surplus individuals” moving into cities from the neighbouring natural populations. Eventually, birds of local origin may constitute a prevailing part of the locally developed synurbic population, thus, overshadowing the early genetic contribution of the very first pioneers. Yet the latter individuals might be important as initiators of the colonization and geographical expansion of this process.
Humans are increasingly becoming urbanized. Because a number of bird species readily live in urban areas and birds are relatively easily observed, birds are becoming the largest everyday encounter with wild fauna people will have, globally. Despite, few studies have been made on how visual (or acoustic) bird encounter affects humans. The few existing studies show that birds provide humans with increased self-evaluated well-being when seeing and hearing them. These values provided by birds can be recognized as a cultural ecosystems service. Here we review extant literature to consider why certain species fascinate humans more than others, and some can increase well-being and provide ecosystem services, while others offer disservices through unappealing characteristics. We particularly highlight indications of links between species diversity and well-being. Finally, we discuss possible reasons for variations in our responses to birds and birdsong associated with age, gender, childhood, contact with nature, and the biophilia theory. If interaction with birds truly increases quality of life, then this value should be considered in the planning of sustainable cities. Both conservation and proper management of existing urban green areas are needed to increase possibilities to encounter many bird species.
Avian communities in urban environments of continental Africa are generally poorly understood. Gauteng, one of South Africa’s nine provinces and the second largest mega-urban region in sub-Saharan Africa, includes the conurbation of Johannesburg and Pretoria. Rapid urbanisation in the province began in the 1880s after the discovery of gold and is, by northern hemisphere standards, a recent urbanisation event; extrapolating patterns of urban ecology from Europe and North America may therefore not be entirely appropriate. The urban transformation and establishment of an anthropogenically modified to natural vegetation gradient, the extension of woodiness (through bush encroachment and fire exclusion) from the savanna biome into grassland, and the ‘greening’ of suburbia with an increase in exotic trees and open water, have resulted in a transformed bird community. This tolerant subset of the local avifauna (both native and alien species), derived from species losses (e.g. grassland-specific species) and gains (species responding to more wooded habitats, e.g. dominated by cavity nesters, frugivores, obligate water-associated species, and cliff nesters), is remarkably diverse and is probably driven and supported by an increase in habitat heterogeneity. An assessment of the bird community at fine- to broad-scale highlights (1) the modifying effect of anthropogenic transformation and the establishment of an urban-resilient bird community brought about by this change, (2) the value of landscape heterogeneity (species composition and structural diversity) in supporting a species-rich bird community, and (3) the value of urban and suburban green spaces as refugia for avian species impacted by urban transformation.
We review the literature on the ecology and conservation of Australian urban birds and report the results of the first Australian study on the relationship between avifauna and habitat variation in exurbia, which is the low-density zone of development on the outer margins of a city. The Australian urban avifauna has synanthropes found widely elsewhere. It also has a large number of native species, some of which are globally threatened. The distribution of species in Australian urban areas relates better to their niche characteristics than their nativity or exoticness and better to very local variations in habitat type than to environmental variation at the landscape scale, which is often masked by the vegetation thickening associated with suburbanisation. In two exurban regions of Hobart, Tasmania, we sampled birds in unmodified wildland forest (native forests away from development), unmodified exurban forest (native forest on exurban properties), modified exurban forest (native forest on exurban properties and with the understorey removed), exurban gardens and exurban paddocks (cleared land). We tested the hypotheses that exurban habitats were different in bird species compositions from wildlands, that similarity in avifaunal assemblages within habitats increased with the degree of human interference and that, within dry open forests, the perforation (small clearances) and fragmentation associated with exurbanisation would be associated with populations of an aggressive small-bird-excluding edge species, the noisy miner Manorina melanocephala. The noisy miner occurred on old land clearance boundaries and not at all in recent forest perforations. In the absence of noisy miners, exurban bird species assemblages were organised by habitat, with the greatest internal consistency being within gardens. In both regions, paddocks had more heterogeneous bird assemblages than expected, and wildlands had identical species assemblages to unmodified exurban forests, but not to other habitat types. The mixture of habitats characteristic of exurbia may not necessarily be detrimental for avifaunal conservation as long as it includes substantial areas of undisturbed native vegetation, even though exurban development may be undesirable for other reasons. We conclude that it is the distinctiveness and high beta diversity of urban and exurban habitats that create opportunities for a wide variety of native and exotic bird species, that local manipulations and creations of urban and exurban habitat can substantially affect avifaunal conservation outcomes and that urban bird management should be a major component of many species recovery plans.
Residential landscapes with private yards and gardens are a major land cover in many cities, represent a considerable opportunity for bird conservation and enhance human experiences with wildlife. The number of studies of birds in residential landscapes is increasing worldwide, but a global-scale perspective on this research is lacking. Here we review the research conducted on birds in residential settings to explore how birds respond to this novel habitat and how private gardens can be designed and managed to enhance their value for bird populations and for human well-being. We examine the key ecological and social drivers that influence birds and draw particular attention to the importance of scale, the role of bird feeding, the predation risk from cats and the relationship between native vegetation and bird diversity. The success of bird conservation initiatives in residential landscapes hinges on collaboration between a range of stakeholders, and we conclude the chapter by making recommendations for urban planners and evaluating policy tools for incentivising householders and communities to conserve birds in their neighbourhoods.
Responses of birds to urbanisation are manifold. Urbanisation directly influences birds by changing ecosystem processes, habitat and food supply; urbanisation indirectly influences birds by affecting their predators, competitors or disease organisms. A special urban habitat is wasteland since it occurs only for short periods in urban agglomerations. Their habitat characteristics could rarely be found in other urban land-use types. In earlier times, large herbivores, fire, floods, windfall, shifting dunes or dynamics of natural river courses removed vegetation and created open landscapes. In human-dominated landscapes, these processes are mostly prevented. In urban settings, building work, demolition and removal of industrial or railroad areas simulate ecological processes that became rare in human-dominated industrial landscapes. Whereas the population dynamics of open-land species in agricultural areas were intensively studied, urban wastelands were rarely examined. These ‘unintentional’ habitats are populated by a number of rare species. Thereby, species differ considerably from each other with regard to their requirements. Some bird species are sensible to human intrusion, some avoid densely built areas, and some are sensitive to the surroundings of habitat patches that are irrelevant for others. Most bird species that prosper in urban habitats are generalists, but also some habitat specialists are under certain conditions able to exploit the resources of an urban environment. The aim of this chapter is to show the state of knowledge on birds on urban wastelands, their value as habitat for endangered bird species and the influence of the urban space that surrounds wastelands on their avifauna.
The implications of invasive plant species on urban avian conservation are complicated and often species or context specific. In the past 20 years, research into the effects of invasive plant species on bird ecology and conservation has increased immensely, thus allowing conservationists to create management practices for the benefit of bird populations. However, until recently, the potential of invasive species to create positive relationships with bird species has been absent from the literature. Recent findings have created a complex puzzle for management of invasive species in order to conserve avian populations in any environment, especially urban areas. Bird communities utilize invasive plants for various aspects of their life histories. In this chapter, I provide evidence for the positive, negative, indirect, and direct effects of invasive plant species on avian communities with a strong focus on the relationship of fruiting invasive plants with native birds. In order to create a relevant discussion, I will use current case studies that are consistent with research from many different areas across the globe. I will then synthesize this discussion into a theory on how invasive plants should be viewed in the paradigm of urban avian conservation. This theory can then be used to discuss possible habitat design and management plans for urban environments and how those may influence other aspects of the environment through their conservation of bird communities.
The richness of all bird species and conservation concern species were investigated in 40 parks and their surrounding built-up areas of 27 Italian towns. Data were obtained from published urban atlases of breeding birds (25 parks) and additional personal communication of Italian ornithologists (15 parks). We define species of conservation concern as those included in the Annex I of EC Directive 09/147/CE and/or in the categories 1–3 of the Species of European Conservation Concern (SPEC). Total species richness and species of conservation concern were compared between the parks and the surrounding built-up areas (500 m around the parks). The role of park features such as size and distance from the centre was investigated for these two parameters. The analysis was repeated for single bird species of conservation concern and for a selection of functional groups of these species. According to homogenising theories of urban areas, no significant differences were observed between parks and surrounding built-up areas for the investigated parameters of breeding bird community and for the frequency of single species. Woodland bird species and woodpeckers of conservation concern were the only groups more diffuse in parks. Conversely, the frequency of building-nesting and aerial feeders was higher in built areas. Variables related to town size and distance from the centre appeared to produce higher effects than park size on species frequencies in parks.
Building and maintaining an urban green infrastructure, which can be understood as a network of urban parks, private gardens or forest areas, can potentially contribute to reverse the trend of biodiversity loss. In this context, developing indicators of the changes produced by green infrastructures on urban biodiversity represents a task of particular interest for planning and governance approaches. The results of long-term bird monitoring schemes in many cities, mainly based on volunteer programmes, may provide a good opportunity to obtain robust data on the spatial patterns and temporal trends of species populations. In addition, recent development of multispecies indicators can now be implemented to make use of common bird monitoring datasets with the aim to generate robust policy relevant evaluation tools. In this chapter we show a procedure to track the effects of urban greening on birds using common bird monitoring data from the city of Barcelona (north-east Iberian Peninsula). Essentially, the proposed approach requires to quantify the species’ response to the green infrastructure at a population level and to integrate all this information in combined indicators of the effect of urban greening. Using this approach we developed a first indicator to track temporal changes on bird populations linked to the greening and a second indicator to determine the areas of the city in which the level of development of the green infrastructure is already having a positive effect on biodiversity.
Managing urban nature to produce public benefit and environmental quality through ecosystem services is a significant objective of urban nature managers. Ecosystem services provided by birds are highly valued and appreciated as birds provide pest control, seed dispersal, nutrient cycling as well as cultural ecosystem services. The aims of this chapter are to (1) provide a review of published experimental studies relating to the management of green areas and bird ecosystem services, (2) describe the findings of our own field experiments in suburban woodlands in southern Sweden, (3) investigate the status of management plans in Swedish cities and (4) discuss how our findings could be implemented in sustainable management planning of urban nature. The main results are:(1) Forest management interventions gave responses that were highly species dependent. Interventions with the object to create or improve bird habitat gave almost entirely positive effects on bird communities. (2) Clearance of bushes and small trees may have a negative impact on the biological control of forest arthropods. The study of bird abundance and understory management showed that clearance of understory can also have negative effects on bird densities if carried out as “complete” clearance (90 % removal of understory). A landscape characterised by high openness in the understory is often favoured by people but may not be an optimal habitat for birds. (3) The management of urban forests and parks can be improved by including informal green space in management plans, putting emphasis on availability of favourable habitats and resources and initiating monitoring programmes for city birds. (4) Urban woodlands would benefit from being managed with an adaptive approach, where management practices are constantly tested and evaluated.
In the last three decades urban bird ecology has experienced a remarkable advance as demonstrated by the rich variety of chapters included in this volume. Nevertheless, there are some research gaps which we try to identify in this chapter, including some issues in current research that to us seem especially pressing. We conclude that a critical examination of bird census techniques in urban areas, an integration of patterns and processes across different spatial scales, the incorporation of temporal dynamics, a more widespread use of experimental or pseudo-experimental design and a deeper insight on sociological and cultural issues are key issues to refine our understanding of the causal connection between urbanisation and bird fauna parameters. Such improvement could help us to shape urban design and management strategies for bird fauna conservation in cities and in the surrounding landscape.
... In particular, there is urgent need for more studies that can inform management decisions by exploring the specific mechanisms that may foster increased community biodiversity and/or presence of individual species of management interest [11]. While an impressive amount of urban ecology research has been carried out in some taxonomic groups, and birds in particular [14][15][16][17], far less is known about reptiles, and how local environmental variables contribute to their persistence in suburban/urban areas. ...
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Urbanization has dramatically altered habitats for local species worldwide. While some species are unable to meet the challenges that these alterations bring, others are able to persist as long as a threshold for suitable habitat is met. For reptiles, a key feature for persistence in urban areas can be access to suitable refuges from predation, high temperatures, and/or other environmental challenges. We tested for effects of local and landscape variables affecting urban occupancy in the Western Fence Lizard, Sceloporus occidentalis, in transects across an urban–rural gradient, with a specific focus on the presence of rock, tree, and shrub refuges. We found that fence lizards were much more likely to be present in areas with more rock cover, and in parks or low-density residential areas. Occupancy was also positively related to canopy cover in the general vicinity, though negatively related to number of trees along the transects. Our results highlight the importance of assessing local habitat features to successfully predict the occupancy of reptile species in urban habitats, and present directions for future research with concrete conservation and management applications.
... Such attributes of habitat disturbance can undeniably impinge dispersal processes. Surprisingly, however, recent research shows that many avian frugivores seem to have developed adaptations in these environments irrespective of the various ecological disturbances they are subjected to (Murgui and Hedblom 2017). Whether these adaptations by avian frugivores translate into stable and thus robust seed dispersal networks in these ecosystems remains unclear. ...
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Animal seed dispersal processes are an important aspect of ecosystem services, as they shape the survival of seed dispersers and the balanced distribution of propagules for many plant communities. Several studies within tropical wild ecosystems have generally shown that seed dispersal processes are highly generalised and robust to extinction. Studies examining seed dispersal networks in highly built-up urban ecosystems and their robustness to species loss or extinction are rare. We examined avian seed dispersal networks across an urban ecosystem characterised by a high human settlement and infrastructure of the built environment in Zambia to determine their network specialisation, interaction evenness and interaction diversity, as these three parameters are critical in driving the resilience of these mutualisms’ interactions against extinction. A total of 405 individuals representing 11 species of birds were observed and recorded feeding on a total of 11 focal fleshy-fruiting plant species. Network specialisation was generally low and remained similar across study areas. Interaction evenness and interaction diversity were not only high but also remained similar across study areas. Low specialisation and high interaction evenness and diversity show that mutualistic interactions in these networks are equally highly generalised, suggesting a stable and robust coexistence of species in plant–frugivore communities within urban ecosystems. Generally, our results seem to broadly suggest that opportunities for conservation still exist in these ecosystems provided urbanisation is accompanied by promoting either the management of remnant fruiting plants or the cultivation of new ones to support the avian communities existing in these areas.
... Considering that urban areas and other human-modified environments hold a high proportion of non-native plants, and that parrots can travel long distances (Tella et al., 2015a(Tella et al., , 2015b, these birds could transport the seeds in their gut from modified environments to natural environments . Thus, these novel interactions could favor both the introduction of plant species into natural environments and the expansion of non-native plant species into the modified environments that are often more susceptible to invasion (Murgui and Hedblom, 2017), both by native and non-native parrot species. Our review indicates that the interaction of non-native parrots with native and non-native plants, and the impact at community level of these novel interactions, have been poorly studied. ...
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Parrots, and their fundamental role in the ecosystems played by the gradient of antagonistic-mutualistic interactions with plant communities, are currently under threat by anthropic activities. We reviewed scientific knowledge of antagonistic-mutualistic interaction between parrot and plant species, focusing on two key global change drivers: urbanization and species introduction. For this, we analyzed the state of knowledge on plant-parrot interactions considering their origin (native or non-native), and the environment type (natural, anthropic/non-urban and anthropic/urban) where interactions were studied. We analyzed 149 articles studying interactions between 126 parrot species and 1758 plant species. Most of these articles focused on the role of parrots as predators, as dispersers and/or pollinators, though very few studies focused on the net result of more than one interaction simultaneously. Articles focused mostly on native parrots interacting with native plants; although this changed with the environment type, single studies did not compare such differences. In natural and non-urban anthropic environments native parrots interacted mostly with native species. In urban areas both native and non-native parrots interacted with plants of both origins. We, here, provide recommendations based on our results and highlight important knowledge gaps to be filled related to interactions between parrot-plant along the antagonistic-mutualistic gradient, focusing on non-native species, and anthropic environments. Understanding the full range of the ecological interactions of parrots, and how they are affected by anthropic activities, will provide us with crucial information about the functioning of the environments they live in, which is also essential for the design of effective conservation strategies.
... Beyond the vast number of species observed in urban areas, birds are the most easily studied and survey group of vertebrates and are often used as surrogates for the status of other wildlife species or natural communities (Murgui and Hedblom, 2017). ...
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In cities, species have to endure severe biotic and abiotic changes in their surroundings, along with various anthropogenic pressures. In recent years, urban dwellers have declined throughout the world, including the most successful urban adapters‒ House Sparrow and Tree Sparrow. We studied how the population and habitat use of sparrows varied at different urban habitats (city outskirts, followed by residential and highly crowded commercial zones) of Guwahati, India. We carried out point counts using distance sampling to estimate the density of sparrows. We found that sparrows were largely associated with complex urban structures, and the density of sparrows significantly differed between species amongst the habitat. House Sparrow density was three-fold of Tree Sparrow, and the occurrence of both the species was highest at mid-level of urbanization. Tree sparrow had low density compared to House Sparrow in areas where urbanization peaked. Unlike Tree Sparrow, the habitat-specific detection for House Sparrow did not vary significantly. The detectability of Tree Sparrow was higher in residential buildings. The Manly Selectivity ratio for the preference and avoidance of different habitats showed that House Sparrows occupied commercial areas and a combination of commercial-residential sectors more than available and avoided areas with a low level of urbanization (city outskirts). Tree sparrows significantly preferred human habitation dominated by residential houses. We estimated around four hundred thousand sparrows (House Sparrow: 253,615‒357,454; Tree Sparrow: 32,882‒163,533) in Guwahati. The present study creates a baseline information for the sparrow population and habitat use in Guwahati City, and provides emphasis for maintaining (mid-level urbanized) areas where both the species are abundant.
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Riparian zone possesses ecological position with biota differing from aquatic body and terrestrial lands, and plant-animal coevolution may be the main factor for the framework of riparian vegetation. In the current study, the riparian plant community patterns along the subtropical mountainous riparian belts of Chongqing, China, was proposed to be regulated by co-evolving with the avifauna through propagule-dispersal process. The results show that: 1) the forests’ species composition and vertical layers are dominated by native catkins of Moraceae species with adapting traits of small and numerous propagules to frugivorous bird species, revealing an evolutionary trend different from the one in the terrestrial plant climax communities in the subtropics, and which forms a biological base for the plant-bird co-evolution; 2) there are significant associations of plant-bird species clusters, i.e., four plant-bird co-evolution groups (PBs) were divided out according to the plant species’ dominance and growth form relating to the fruit-dispersing birds’ abundance; 3) the correlation intensity within PB ranks as PBⅠ>Ⅱ>Ⅳ>Ⅲ, indicating the PBⅠis the leading type of co-evolution mainly shaped by the dominant plant species; 4) the PB correlation may be a key node between patterns vs. process of a riparian ecosystem responsible for the native vegetation, or even the ecosystem health. The results theoretically contribute new evidence to plant-animal co-evolution interpreting the forests’ characters in riparian environments, and urban planner and managers may simulate the native forests for restoring a more stable riparian biota, a better functioning ecosystem in subtropical zone.
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