42 research outputs found

    Urbanisation and nest building in birds: a review of threats and opportunities

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    SJR would like to thank his undergraduate (Connor Barnes, Clare Davies, Emily Elwell, Corrie Grafton, Jacob Haddon, Claire Herlihy, Derek Law, Eleanor Leanne, Holly Mynott, Penny-Serena Pratt, Anna Smith, Peter Tasker, Alison Wildgoose, Amy Williams and Daniel Woodward) and postgraduate (Richard Bufton, Dan Hunt, Victoria Pattison-Willits and Jen Smith) ‘nest’ students, and Charles Deeming, who have all provided new insights about urban nests over the last few years. MCM thanks Charles Deeming, Tom Martin, Bret Tobalske and Blair Wolf for useful discussions on the topic of urban nesting birds. PS would like to thank the participants of the ‘Human-Raptor Interactions—From Conservation Priorities to Conflict Mitigation’ symposium, Arjun Amar, Daniel Berkowic, Shane McPherson and Steve Redpath for the useful discussions on the topic of urban conservation regarding human–wildlife conflicts. JDI-Á would like to thank Olivia Sanllorente for providing interesting discussions on the topic and her constant support. Finally, we all thank Dan Chamberlain and an anonymous reviewer for helpful comments that improved the manuscript significantly.The world is urbanising rapidly, and it is predicted that by 2050, 66% of the global human population will be living in urban areas. Urbanisation is characterised by land-use changes such as increased residential housing, business development and transport infrastructure, resulting in habitat loss and fragmentation. Over the past two decades, interest has grown in how urbanisation influences fundamental aspects of avian biology such as life-history strategies, survival, breeding performance, behaviour and individual health. Here, we review current knowledge on how urbanisation influences the nesting biology of birds, which determines important fitness-associated processes such as nest predation and community assembly. We identify three major research areas: (i) nest sites of birds in urban areas, (ii) the composition of their nests, and (iii) how these aspects of their nesting biology influence their persistence (and therefore conservation efforts) in urban areas. We show that birds inhabiting urban areas nest in a wide variety of locations, some beneficial through exploitation of otherwise relatively empty avian ecological niches, but others detrimental when birds breed in ecological traps. We describe urban-associated changes in nesting materials such as plastic and cigarette butts, and discuss several functional hypotheses that propose the adaptive value and potential costs of this new nesting strategy. Urban areas provide a relatively new habitat in which to conserve birds, and we show that nestboxes and other artificial nest sites can be used successfully to conserve some, but not all, bird species. Finally, we identify those subject areas that warrant further research attention in the hope of advancing our understanding of the nesting biology of birds in urban areas

    Raptor research during the COVID-19 pandemic provides invaluable opportunities for conservation biology

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    Authors acknowledge financial support from: the Dean Amadon Grant of the Raptor Research Foundation (to PS); the Raptor Research and Conservation Foundation, Mumbai, and the University of Oxford's Global Challenges Research Fund through the Ind-Ox initiative (KCD00141-AT13.01) (both to NK), and the Gordon and Betty Moore Foundation (GBMF9881) and the National Geographic Society (NGS-82515R-20) (both to CR).Research is underway around the world to examine how a wide range of animal species have responded to reduced levels of human activity during the COVID-19 pandemic. In this perspective article, we argue that raptors are particularly well-suited for investigating potential ‘anthropause’ effects, and that the resulting insights will provide much-needed impetus for global conservation efforts. Lockdowns likely alter many of the extrinsic factors that normally limit raptor populations. These environmental changes are in turn expected to influence – mediated by behavioral and physiological responses – the intrinsic (demographic) factors that ultimately determine raptor population levels and distributions. Using this framework, we identify a range of research opportunities and conservation challenges that have arisen during the pandemic. The COVID-19 anthropause allows raptor researchers to address fundamental and applied research objectives in a large-scale, quasi-experimental, well-replicated manner. Importantly, it will be possible to separate the effects of human disturbance and anthropogenic landscape modifications. We explain how high-quality datasets, accumulated for a diverse range of raptor species before, during, and after COVID-19 lockdowns, can be leveraged for powerful comparative analyses that attempt to identify drivers of particular response types. To facilitate and coordinate global collaboration, we are hereby launching the ‘Global Anthropause Raptor Research Network’ (GARRN). We invite the international raptor research community to join this inclusive and diverse group, to tackle ambitious analyses across geographic regions, ecosystems, species, and gradients of lockdown perturbation. Under the most tragic of circumstances, the COVID-19 anthropause has afforded an invaluable opportunity to significantly boost global raptor conservation.Publisher PDFPeer reviewe

    Reduced ectoparasite load, body mass and blood haemolysis in Eurasian kestrels (Falco tinnunculus) along an urban-rural gradient

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    Urbanisation is proceeding at an alarming rate which forces wildlife to either retreat from urban areas or cope with novel stressors linked to human presence and activities. For example, urban stressors like anthropogenic noise, artificial light at night and chemical pollution can have severe impacts on the physiology of wildlife (and humans), in particular the immune system and antioxidant defences. These physiological systems are important to combat and reduce the severity of parasitic infections, which are common among wild animals. One question that then arises is whether urban-dwelling animals, whose immune and antioxidant system are already challenged by the urban stressors, are more susceptible to parasitic infections. To assess this, we studied nestlings of Eurasian kestrels (Falco tinnunculus) in Vienna, Austria, during 2015 and 2017. We measured biomarkers of innate immune function, oxidative stress and body mass index and ectoparasite infection intensity in 143 nestlings (from 56 nests) along an urban gradient. Nestlings in more urbanised areas had overall fewer ectoparasites, lower haemolysis (complement activity) and lower body mass index compared to nestlings in less urbanised areas. None of the other immune or oxidative stress markers were associated with the urban gradient. Despite some non-significant results, our data still suggest that kestrel nestlings experience some level of reduced physiological health, perhaps as a consequence of exposure to more urban stressors or altered prey availability in inner-city districts even though they had an overall lower ectoparasite burden in these heavily urbanised areas.</p

    Innate immune function and antioxidant capacity of nestlings of an African raptor covary with the level of urbanisation around breeding territories

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    Urban areas provide breeding habitats for many species. However, animals raised in urban environments face challenges such as altered food availability and quality, pollution and pathogen assemblages. These challenges can affect physiological processes such as immune function and antioxidant defences which are important for fitness. Here, we explore how levels of urbanisation influence innate immune function, immune response to a mimicked bacterial infection and antioxidant capacity of nestling Black Sparrowhawks Accipiter melanoleucus in South Africa. We also explore the effect of timing of breeding and rainfall on physiology since both can influence the environmental condition under which nestlings are raised. Finally, because urbanisation can influence immune function indirectly, we use path analyses to explore direct and indirect associations between urbanisation, immune function and oxidative stress. We obtained measures of innate immunity (haptoglobin, lysis, agglutination, bactericidal capacity), indices of antioxidant capacity (total non-enzymatic antioxidant capacity (tAOX) and total glutathione from nestlings from 2015 to 2019. In addition, in 2018 and 2019, we mimicked a bacterial infection by injecting nestlings with lipopolysaccharide and quantified their immune response. Increased urban cover was associated with an increase in lysis and a decrease in tAOX, but not with any of the other physiological parameters. Furthermore, except for agglutination, no physiological parameters were associated with the timing of breeding. Lysis and bactericidal capacity, however, varied consistently with the annual rainfall pattern. Immune response to a mimicked a bacterial infection decreased with urban cover but not with the timing of breeding nor rainfall. Our path analyses suggested indirect associations between urban cover and some immune indices via tAOX but not via the timing of breeding. Our results show that early-life development in an urban environment is associated with variation in immune and antioxidant functions. The direct association between urbanisation and antioxidant capacity and their impact on immune function is likely an important factor mediating the impact of urbanisation on urban-dwelling animals. Future studies should explore how these results are linked to fitness and whether the responses are adaptive for urban-dwelling species

    Landscape homogenization due to agricultural intensification disrupts the relationship between reproductive success and main prey abundance in an avian predator

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    Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. However, few studies have investigated the interplay between land cover heterogeneity, limitation in food resources, individual quality and spatial variation in fitness parameters. Here, we explore how individuals of different quality respond to possible mismatches between a cue for prey availability (land cover heterogeneity) and the actual fluctuating prey abundance.Peer reviewe

    Hazards in the Urban Jungle: Managing Human-wildlife Conflicts of Crowned Eagles

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    Time-lapse camera studies at urban nest sites demonstrated low rates of predation on livestock (6%) and pets (1%). Reported pet attacks were primarily by juveniles and sub-adults, and most occurred during winter months. Collaboration of wildlife authorities with NGO’s and public stakeholders input creates an environment for successful crowned eagle conservation and management of human-wildlife conflicts. Active management and falconry-based rehabilitation processes can achieve a high standard of public support and conservation outcomes for human wildlife conflict concerning crowned eagles
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