Urban Wildlife Research Articles

No city for wetland species: habitat associations affect mammal persistence in urban areas.

The fast rate of replacement of natural areas by expanding cities is a key threat to wildlife worldwide. Many wild species occur in cities, yet little is known on the dynamics of urban wildlife assemblages due to species' extinction and colonization that may occur in response to the rapidly evolving conditions within urban areas. Namely, species' ability to spread within urban areas, besides habitat preferences, is likely to shape the fate of species once they occur in a city. Here we use a long-term dataset on mammals occurring in one of the largest and most ancient cities in Europe to assess whether and how spatial spread and association with specific habitats drive the probability of local extinction within cities. Our analysis included mammalian records dating between years 1832 and 2023, and revealed that local extinctions in urban areas are biased towards species associated with wetlands and that were naturally rare within the city. Besides highlighting the role of wetlands within urban areas for conserving wildlife, our work also highlights the importance of long-term biodiversity monitoring in highly dynamic habitats such as cities, as a key asset to better understand wildlife trends and thus foster more sustainable and biodiversity-friendly cities.

Pesticide Contamination Levels in the Stomach Contents of Wild Raccoons (Procyon lotor) and Masked Palm Civets (Paguma larvata) in Japan.

Pesticides, which are vital for agriculture, pose a significant threat to wildlife in transformed Japanese landscapes. Despite global reports of pesticide poisoning in animals, limited studies have examined current wildlife exposure in croplands or metropolitan areas in the region. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), our study aimed to assess the contamination status of 368 commonly used pesticides. The stomach contents of raccoons living in croplands contained 13 pesticides, including six herbicides and 11 fungicides. Neonicotinoid insecticides, some fungicides, and previously banned insecticides (benzene hexachloride and dichlofenthion) were most frequently detected and found at the highest concentrations, suggesting direct soil-plant transfer and direct consumption by crop-eating species. In masked palm civets living in metropolitan areas, four insecticides and six fungicides were detected, indicating urban wildlife exposure from raided dustbins, urban gardens, and lumber from houses. Although the maximum measured concentrations of all pesticides were lower than the acceptable daily intake for humans, it remains unclear whether these concentrations may have toxic or adverse health effects on the species evaluated in these transformed landscapes. Our study is the first to examine recent pesticide exposures in wild mammals in Japan. Application of the method we developed will lay the foundation for the examination of pesticides in other wildlife species to assist conservation management efforts in the region. Environ Toxicol Chem 2024;43:943-951. © 2024 SETAC.

Lion City Zoopolis: Urban Crittizenship in Biophilic Singapore

ABSTRACT A central theme of Singapore’s “City in Nature” vision is framed through biophilic urbanism, or efforts to harmonize biodiversity and urban development through built, social, and political design. The central discourses of Singapore’s biophilic urbanism have revolved around flora-centric paradigms, including habitat conservation, greening spaces, and access to natural capital. This paper detours from conventions of Singapore’s urban ecological futures and instead explores the governance of fauna co-existence in the city–state through the concept of “urban crittizenship.” Defined as a more-than-human denization framework that interrogates urban wildlife governance, urban crittizenship interrogates the politics of urban wildlife’s rights to the city. Drawing on interviews, publicly accessible data, and ethnographic findings with local governing actors and activists, I show that Singapore’s experience of urban fauna governance is framed through three categories (“resident,” “wildlife,” and “pest”) and that they inform how state and society mediate and manage coexistence with urban wildlife. These experiences are examined through the examples of otters, boars, and pigeons, respectively. In doing so, I present urban crittizenship as an inductive model of analyzing urban wildlife coexistence as primarily secured through infrastructural and political regime configurations that inform their crittizenship statuses. Any real shifts toward new forms of coexistence must therefore begin with actual transformations in these areas. I further iterate that using an urban crittizenship framework refines our understanding and application of biophilic urbanism as socio-political processes that influence already-existing urban wildlife coexistence, complementing existing analyses in urban ecology. In other words, there is a politics of biophilia that warrants a conversation, because biophilia is political.

Ecological traits predict population trends of urban birds in Europe

The population dynamics of urban animals has been so far remarkably understudied. At the same time, urban species’ population trends can provide important information on the consequences of environmental changes in cities. We modelled long-term population trends of 93 bird species breeding in urban areas in 16 European countries as a function of species’ traits, characterising variability in their urbanization and ecology. We found that: (i) earlier colonisers have more negative population trends than recent colonisers; (ii) more urbanized open habitat species had more positive population trends than less urbanized open habitat species; (iii) highly urbanized birds breeding above the ground had more negative trends than highly urbanized ground breeders. These patterns can be explained by several processes occurring in cities as well as outside city borders. Namely, (i) pre-industrial colonisers might struggle to persist in rapidly changing urban areas, limiting their foraging and breeding opportunities of the birds. (ii) Open habitats are under pressure of intensive agricultural exploitation in rural areas, which may negatively affect populations of less urbanized birds. In contrast, urban areas do not experience such pressure keeping the trends of urbanized open habitat species more positive. (iii) Differences in population trends between highly urbanized ground and above-ground breeders suggest that the latter may lose their breeding opportunities in modern buildings that do not provide suitable breeding sites. Our results indicate that even once successful, city dwellers may not keep pace with changes in urban areas, but these areas may also provide suitable habitats for biodiversity.

There is a place for every animal, but not in my back yard: a survey on attitudes towards urban animals and where people want them to live

Abstract Animals are a constant presence in urban environments. While there is a handful of studies that have addressed which urban animals people like, there is little knowledge on where in the city people want them to be. There is the risk of a misalignment between human urban inhabitants’ specific desires for more nature in cities and the results of urban renaturing initiatives. We conducted an online survey on inhabitants of Munich (Germany) to investigate their attitudes towards 32 different urban animals and where they want them to occur. These places ranged from their own home or garden, to different places within the city, and to outside of the city. In total, 10 000 flyers were distributed in houses surrounding 40 city squares, and 305 people participated. We found that people rather placed animals further away than close to home. There were clear differences between different animal species in where they were placed by people, from species being placed close to home, to species wanted only outside the city. There were also clear differences in attitude towards the different animals, and participants on averaged placed animals closer to home if they liked them more. People have clear preferences for the placing of different animals in an urban context. Knowledge on these preferences can help to design targeted conservation actions and environmental education programs.

ANALYSIS OF THE DEGREE OF STUDY AND GLOBAL EXPERIENCE IN OPTIMIZING URBAN NOISE POLLUTION

А collection and analysis of domestic and international publications on the impact of noise pollution on the physical and emotional well-being of mega-city residents were conducted. It was found that noise pollution directly affects the quality of life and the physical and mental health of people, leading to significant economic losses through medical expenses, deaths, and a decrease in the market value of real estate located near noise sources. Moreover, it was discovered that noise negatively influences not only the physical well-being of humans but also the behavior of urban animals and birds, compelling them to adapt their mating rituals and communication methods. While these behavioral changes help animals be more audible in noisy environments, they impact the reproductive success of certain species, potentially leading to their extinction and causing an ecological catastrophe. The study identified a global trend of lagging efforts to combat urban noise and solve problems only after their existence is acknowledged. The research explored the primary internationally recognized and widely used tools for reducing noise levels in urban environments, including methods within the field of landscape architecture: functional zoning of urban areas, construction of noise reduction screens (NRS), installation of noise-absorbing road surfaces, traffic restrictions, or speed limits, and the creation of green barriers, among others. Furthermore, the article outlined the main trends in the future development of improving sound comfort in cities, such as the establishment of "quiet zones" and the creation of unique soundscapes in contemporary mega-cities. Examples include the iconic sounds of Big Ben in London or the call to prayer from the Masjid al-Haram in Mecca, which provide emotionally rich experiences. In a broader sense, acoustic comfort should not be considered solely as the absence of noise but rather as a situation where acoustic environments offer significant opportunities for human development and careful consideration of their physical and mental well-being.

Dynamic connectivity assessment for a terrestrial predator in a metropolitan region

Protecting wildlife movement corridors is critical for species conservation. Urban planning often aims to create corridors for animal movement through conservation initiatives. However, research on connectivity for urban wildlife is limited. Here, we assessed connectivity for coyotes (Canis latrans) dynamically across temporal scales and demographic traits, parametrized using the habitat selection of 27 global positioning system (GPS)‐collared coyotes in the city of Toronto, Canada. The habitat selection models accounted for human population density, impervious area, vegetation density, and distance to different linear features. Results indicated that (1) vegetation‐dense areas were key for connectivity in urban areas; (2) riverbanks, railways, and areas below power lines were predicted as movement corridors; and (3) commercial and industrial clusters strongly disrupted connectivity. Spatiotemporal differences in connectivity were associated with time of day and coyote social status but not with climate and biological seasonality or coyote age and sex. Residential roads were pivotal in the temporal dynamism of connectivity. The maintenance and enhancement of plant structural complexity along key infrastructure (for example, highways, waterways, and parking lots) should be considered when managing connectivity corridors in cities.

The functional microclimate of an urban arthropod pest: Urban heat island temperatures in webs of the western black widow spider

Urbanization alters natural landscapes and creates unique challenges for urban wildlife. Similarly, the Urban Heat Island (UHI) effect can produce significantly elevated temperatures in urban areas, and we have a relatively poor understanding of how this will impact urban biodiversity. In particular, most studies quantify the UHI using broad-scale climate data rather than assessing microclimate temperatures actually experienced by organisms. In addition, studies often fail to address spatial and temporal complexities of the UHI. Here we examine the thermal microclimate and UHI experienced in the web of Western black widow spiders (Latrodectus hesperus), a medically-important, superabundant urban pest species found in cities across the Western region of North America. We do this using replicate urban and desert populations across an entire year to account for seasonal variation in the UHI, both within and between habitats. Our findings reveal a strong nighttime, but no daytime, UHI effect, with urban spider webs being 2–5 °C warmer than desert webs at night. This UHI effect is most prominent during the spring and least prominent in winter, suggesting that the UHI need not be most pronounced when temperatures are most elevated. Urban web temperatures varied among urban sites in the daytime, whereas desert web temperatures varied among desert sites in the nighttime. Finally, web temperature was significantly positively correlated with a spider's boldness, but showed no relationship with voracity towards prey, web size, or body condition. Understanding the complexities of each organism's thermal challenges, the “functional microclimate”, is crucial for predicting the impacts of urbanization and climate change on urban biodiversity and ecosystem functioning.

Urban-use pesticides in stormwater ponds and their accumulation in biofilms

Stormwater ponds frequently receive urban runoff, increasing the likelihood of pesticide contamination. Biofilms growing in surface waters of these ponds are known to accumulate a range of aquatic contaminants, paradoxically providing both water purification services and potentially posing a threat to urban wildlife. Thus, sampling biofilms in stormwater ponds may be a critical and biologically relevant tool for characterizing pesticide contamination and toxicity in urban environments. Here, we aimed to investigate pesticide occurrences at 21 stormwater ponds in Brampton, ON, one of Canada's fastest growing municipalities, and quantify their accumulation in biofilm. Over nine weeks, we collected time-integrated composite water and biofilm samples for analysis of ∼500 current-use and legacy pesticides. Thirty-two pesticide compounds were detected across both matrices, with 2,4-D, MCPA, MCPP, azoxystrobin, bentazon, triclopyr, and diuron having near-ubiquitous occurrences. Several compounds not typically monitored in pesticide suites (e.g., melamine and nicotine) were also detected, but only in biofilms. Overall, 56 % of analytes detected in biofilms were not found in water samples, indicating traditional pesticide monitoring practices fail to capture all exposure routes, as even when pesticides are below detection levels in water, organisms may still be exposed via dietary pathways. Calculated bioconcentration factors ranged from 4.2 to 1275 and were not predicted by standard pesticide physicochemical properties. Monitoring biofilms provides a sensitive and comprehensive supplement to water sampling for pesticide quantification in urban areas, and identifying pesticide occurrences in stormwater could improve source-tracking efforts in the future. Further research is needed to understand the mechanisms driving pesticide accumulation, to investigate toxicity risks associated with pesticide-contaminated biofilm, and to evaluate whether pesticide accumulation in stormwater pond biofilms represents a route through which contaminants are mobilized into the surrounding terrestrial and downstream aquatic environments.

Managing Landscape Urbanization and Assessing Biodiversity of Wildlife Habitats: A Study of Bobcats in San Jose, California

In the rapid process of urbanization, crucial habitats for mid-sized felids such as bobcats are increasingly compromised. This study employs Geographic Information System (GIS) tools and Machine Learning to investigate the subtle impacts of urbanization on bobcat habitats. Focused on the San Jose area, our extensive geospatial analysis has developed a complex ecological model for bobcat habitats. Our findings emphasize the significant influence of factors like vegetation cover, water body distribution, road traffic volume, and intersection density on the suitability of habitats for bobcats. Specifically, we discovered that while vegetation cover typically supports habitat suitability, its proximity to busy roads significantly undermines this advantage, indicating a need for strategic urban planning that incorporates wildlife mobility. By synthesizing natural and urban elements, we offer fresh insights into urban ecosystem management and propose specific conservation tactics: identifying optimal wildlife crossings, integrating corridors with urban infrastructure, and placing fencing and signage strategically to facilitate wildlife movement safely. These measures aim to reduce road-related threats and enhance the integrity of natural habitats, strengthening bobcat conservation efforts. More than its direct implications for bobcat conservation, this study offers actionable insights for urban wildlife conservation and introduces innovative methods for assessing and mitigating the broader ecological impacts of urbanization.

A Canadian children's hospital's experience with cystic echinococcosis over 30 years: A case series.

Cystic echinococcosis (CE) or hydatid disease caused by the cestode Echinococcus granulosus sensu lato is an uncommon infection in Canada especially among children. There are limited reports describing the clinical presentation and management in Canadian children. The medical records of all children diagnosed with CE at a quaternary paediatric centre in Ontario between January 1988 and August 2021 were retrospectively reviewed. The clinical course, management, and outcomes of each case were summarized. We report two paediatric cases of cystic echinococcosis (CE) in detail and review four additional cases seen at our institution over 33.5 years. The first case was a previously healthy 12-year-old boy with pulmonary CE resulting in unilateral lung collapse and mediastinal shift, who was presumedly infected while living in the Middle East. The second case was a previously healthy 3-year-old girl with pulmonary CE acquired locally in southern Ontario. Four other cases of CE with hepatic involvement (median age 12.5 years) were identified during the study period. Five out of six patients received both surgical and medical therapy. CE is a rare but serious disease seen in southern Canada that has historically been associated with travel or migration. Due to changes in urban wildlife landscapes and increased global migration, CE may become more prevalent in Canadian children. We describe the first locally acquired case in rural southern Ontario diagnosed at our centre. Prompt recognition of this infection in children by health care providers is important to prevent morbidity and mortality.

Engaging urban residents in the appropriate actions to mitigate human–wildlife conflicts

AbstractMitigating human–wildlife conflicts by altering human behaviors is critical to urban wildlife conservation. We investigated what actions urban residents are willing to take to mitigate human–wildlife conflicts in metropolitan Atlanta, one of the fastest growing metropolises in the United States (~6.1 million people, 21,690 km2). In 2022, we administered online surveys to 1006 residents of metropolitan Atlanta to determine which measures they had adopted to mitigate conflicts with urban wildlife, elicit their stated willingness to adopt additional conflict mitigation measures, and identify determinants of current or potential implementation of mitigation measures. Respondents most frequently reported watching urban wildlife (63.0% of respondents). The most frequently reported conflicts were wildlife raiding trash cans (14.8%) and damaging landscaping (20.8%). In total, 342 respondents (34.0%) had not taken any action to mitigate conflicts with wildlife. Respondents who had taken action to prevent conflicts most often secured their trash by keeping cans indoors or locking the lid of the can (28.7%), kept pets (20.5%) and pet food (20.3%) indoors, and took trash out on the morning of collection (19.6%). Respondents who had not adopted conflict mitigation measures stated that they were likely to secure their trash or keep pets and pet food indoors if they considered these measures to be necessary. Prior conflicts with wildlife influenced both respondents' current efforts to mitigate conflicts with wildlife, and their stated willingness to adopt additional measures to mitigate human–wildlife conflicts. Risk sensitivity to zoonotic pathogen transmission increased both actual and intended adoption of conflict mitigation measures. Respondents' self‐efficacy, beliefs about wildlife, and age also influenced their willingness to adopt conflict mitigation measures. Our results suggest that education and outreach about the need for conflict mitigation measures should highlight the importance and effectiveness of these measures in conserving wildlife, while also securing the well‐being of humans and pets.

Coyote scat in cities increases risk of human exposure to an emerging zoonotic disease in North America

IntroductionZoonoses associated with urban wildlife are increasingly concerning for human health and include the recent emergence of alveolar echinococcosis (AE) in North America. AE develops following infection with the tapeworm Echinococcus multilocularis. In Alberta, up to 65% of urban coyotes (Canis latrans) are infected with E. multilocularis, and infected scats contain eggs that can be accidentally ingested by people. Our goal was to determine the predictors of infection prevalence and intensity in coyote scats in Edmonton, Canada, and to identify the predictors of coyote scat deposition and content, especially as related to anthropogenic food sources and infrastructure.MethodsTo study infection prevalence and intensity, volunteers collected 269 scats, which were tested for E. multilocularis using polymerase chain reaction. We compared infection prevalence and shedding intensity by habitat and scat content. To determine predictors of scat presence and content, we used snow tracking to identify 1263 scats. We compared landscape characteristics at scats and available points, and among scats with different contents. We used negative binomial regression to predict scat abundance in city-delineated green spaces.Results26.0% of tested scats were positive for E. multilocularis (n = 70), and infection was twice as common as expected near compost and 1.3x more common than expected when scats contained anthropogenic food. Scats were more common than expected near other scats (80% within 1 m of scats, 27% at 11.5 m), buildings (19% at buildings, 16% at 80 m), and the camps of people experiencing homelessness (24% at camps, 20% at 60 m). Scats frequently contained fruit (52.9%), anthropogenic material (36.7%), and birdseed (16.0%), and scats containing anthropogenic material often occurred near human infrastructure, supporting a relationship between anthropogenic attractants and scat accumulation.DiscussionThese results suggest that abundant food sources and anthropogenic food increase coyote aggregation, increasing both scat abundance and infection rates, which in turn increases risk of exposure to zoonotic parasites for humans. Risk to humans might be reduced by preventing coyote access to anthropogenic and aggregated food sources and educating people who are likely to encounter infected soil or vegetation, including gardeners, park users, and people experiencing homelessness.

Analysis of the Decisive Factors of Government Attracting Tourists in Public Management from the Perspective of Environmental Protection

Tourism is a critical sustainable social and economic activity that can empower local communities. The current study strived to explore decisive factors that might be used it promotes environmental protection. Governments worldwide might employ to improve conservation and the tourism sector. There is a need to sponsor more publications on tourism and the environment that provide rigor, insight, and significance. There is also a need to address critical impacts, including greenhouse gases for airlines, liquid wastes for cruise ships, water and energy conservation for urban hotels, vegetation clearance, and wildlife displacement for rural resorts, and a range of direct and indirect local impacts on plants and animals for nature-based and adventure tourism in parks and wilderness areas. Governments need to work on economic models that address; currency exchange rates; airfares and taxes; land tenure and wildlife ownership laws; transport infrastructure; police, quarantine, and border security; investment law; public protected-area systems; and a variety of social pressures and fashions. The most effective means to improve environmental management in tourism is through laws and regulations for development planning, pollution control, and protected areas. In developed nations, tourism threatens conservation as property developers push to build private facilities inside public protected areas. In developing nations, tourism is a tool to fund conservation in public parks and private or communal lands. Visitors to the public, and protected areas contribute political and financial capital to park agencies. A few private tourism operators have converted areas of private and communal land to conservation.

What informs human–nature connection? An exploration of factors in the context of urban park visitors and wildlife

Abstract Human–nature connection (HNC) is a concept derived from investigating the formulation and extent of an individual's identification with the natural world. This relationship is often characterized as an emotional bond to nature that develops from the contextualized, physical interactions of an individual, beginning in childhood. This outcome presents complexity in evaluating the development of HNC but suggests optimism in the pathways for enhancing lifelong HNC. As urban populations increase, there is a growing recognition worldwide of the potential for urban green space to cultivate HNC and thus shape the environmental identity of urban residents. The results of an online survey of 560 visitors to three community parks (managed primarily to provide a variety of physical, social and cultural opportunities) and three conservation parks (managed primarily to protect native plants and wildlife) in Madison, Wisconsin, USA, were used to investigate HNC. Linear mixed effects models evaluated visitors' HNC as a function of their (1) literacy and sentiment about wildlife species, (2) park experience, (3) number and frequency of nine childhood and adult recreation experiences, and (4) demographics. Across the park response groups, the number and frequency of childhood and adult recreation experiences was significantly associated with HNC, and this positive association persisted in multiple recreation activities. Furthermore, species literacy and sentiment, visiting a park for ‘Nature’, and frequent and extended visitation also was significantly associated with HNC by park type. Our research demonstrates the importance of lifelong recreation experiences in the development and enhancement of HNC and provides evidence for differences in the expression of HNC associated with particular attributes of urban park visitors and their views of wildlife. Read the free Plain Language Summary for this article on the Journal blog.

The use of seismically isolated buildings by urban wildlife in Japan.

Some wildlife species that have expanded their range into urban areas use various anthropogenic structures for breeding and resting. We investigated the use of seismically isolated buildings, with gaps between the structures and ground surface, by urban wildlife in Japan. Camera traps set in a building revealed that masked palm civets (Paguma larvata) continued to use the building for approximately 3 years. Civet feces and footprints were found in two buildings during field sign surveys. To ensure public health, civets should be prevented from invading seismically isolated buildings by covering gaps with elastic materials and avoiding placing pipes that could be used by the animals near these gaps.

Bio-Inclusive Urban Ecosystems and their Conservation - A Review

This article dives into the usage of nature in cities to solve today's problems. This research focuses on the systematic conservation of urban wildlife. How the cities can be interlinked with the wildlife and the current scenarios which happen in the present condition of the cities. We deal with classification of the urban ecosystem and also the new habitats for the wildlife population and the factors that affect the same. The six main areas in which urban wildlife management challenges now exist are also covered. We get the chance to study more about the new term of synurbization and the factors and conditions for the same and some examples also. Further, the research focuses on the habitat management techniques and the examples happening in different areas in the world.Another major topic which is dealt in this study is the wetlands of India. Wetlands of kerala are also studied along with their respective policies and strategies for the protection of wetlands. National strategy for wetland protection and the methods used for the monitoring and protection of wetlands are also included.Human activities and human interventions are the major factors that contribute to the depletion of wildlife and the wetlands therefore habitat conservation is also dealt with in this study. This study helps us to understand the importance of protection and prevention of wildlife in urban areas and the conservation of wildlife in different zones of our cities and urges us to understand the factors responsible for the urban development without affecting the ecosystem.

Morphology and reproduction of the common opossum (Didelphis marsupialis) dwelling in urban vs rural environments in Antioquia, Colombia

Background: Urban wildlife has been increasing during the last years, however the effect of urbanization on it is poorly understood. The common opossum (Didelphis marsupialis) is very frequent in the Metropolitan Area of Valle del Aburrá (AMVA), in Antioquia, Colombia, where there is also a strong opossum-human conflict that results in a large number of injured/dead opossums. Objective: We evaluated the effects of urban and rural habitats on the morphometry and the reproductive output (litter size in marsupium) of opossums. Methods: A total of 131 opossums were captured, 94 from the AMVA, and 37 from rural areas of Antioquia. Opossums were weighed, measured, sexed, clinically inspected, and photographed. Results: Urban opossums were heavier and larger than rural individuals, regardless of sex, and there were no differences in the reproductive output between the two habitats. Also, urban opossums were more abundant than rural opossums. A potential explanation of these results is that cities favor survival mediated by higher food consumption, but not reproduction. Alternatively, bigger animals could also be explained by an inadequate food consumption rich on carbohydrates which may have potential negative health consequences. We confirmed the sexual size dimorphism of the common opossum in the head and tail lengths but not on the body length. Conclusion: We confirm a significant effect of urban environments on body mass and size of opossums; however, it is unknown whether it is beneficial or detrimental. Litter size is the lowest reported for the species, and there was no difference between rural and urban habitats.

The effects of urban thermal heterogeneity and feather coloration on oxidative stress and metabolism of pigeons (Columba livia)

Urbanization stands out as a significant anthropogenic factor, exerting selective pressures on ecosystems and biotic components. A notable outcome of urbanization is thermal heterogeneity where the emergence of Urban Heat Islands is characterized by elevated air and surface temperatures compared to adjacent rural areas. Investigating the influence of thermal heterogeneity on urban animals could offer insights into how temperature variations can lead to phenotypic shifts. Urban pigeons (Columba livia) serve as an excellent model for studying urban thermal effects, given the melanism variations, which are associated with the pleiotropy of the melanocortin system. To examine the development of physiological plasticity in response to urban thermal variations, we conducted a study on pigeons in Santiago, Chile, during the rainy season. We assessed the influence of habitat on physiological traits related to metabolism and antioxidant capacities, which are theoretically affected by feather coloration. Our findings reveal that variations in melanism significantly impact pigeon physiology, affecting both antioxidant capacities and the mitochondrial activity of red blood cells. It was found that higher urban temperatures, from both the current sampling month and the prior sampling month (from CRU TS dataset), were negatively and strongly associated with lower antioxidant and metabolic activities. This suggests that elevated urban temperatures likely benefit the energetic budgets of pigeon populations and mitigate the negative effects of oxidative metabolism, with differential effects depending on feather colorations.

Mechanisms of trunk cavity formation of large old trees in urban landscapes: A case study on four tree species in Beijing

Cavity trees play a crucial role in enhancing urban biodiversity, despite limited habitat space. Understanding these aspects is of paramount importance for promoting biodiversity in urban environments. Nevertheless, there is a paucity of extensive research on the characteristics and formation mechanisms of cavity trees across diverse tree species in urban landscapes. In this study, Arbotom sonic tree tomography was used to identify cavity cores within four representative large old tree species in Beijing, encompassing two broadleaved species [Styphnolobium japonicum (L.) Schott, n = 301; and Ginkgo biloba L., n = 100] and two conifer species [Platycladus orientalis (L.) Franco, n = 515; and Pinus tabuliformis Carr., n = 404]. We introduce a cavity index to quantify tree decay and explore cavity characteristics and formation mechanisms across different tree species. Our results reveal that the cavity index is primarily linked to diameter at breast height (DBH), tree age, and trunk health in the four large old tree species studied. The formation of cavities in trees is primarily attributed to external disturbances that lead to tree damage. Subsequent fungal infections occur when a tree's defense mechanisms fail to prevent them, resulting in trunk decay and the formation of cavities. It is worth noting that different tree species exhibit varying defense mechanisms, with coniferous species generally displaying stronger defenses than broad-leaved species. In summary, the formation of cavity trees in urban landscapes is influenced by a combination of internal and external factors, with the tree species' defense mechanisms and the extent of external disturbances determining cavity characteristics. The findings indicate a higher likelihood of cavities in the outer parts of large old trees in southern regions compared with those in northern regions. Coniferous species also exhibited fewer cavities than broad-leaved species. Further, urban trees are more susceptible to external damage that can lead to cavity development, thereby necessitating attention to their growth environment and morphological conditions. However, understanding these factors can aid managers in crafting conservation policies that enhance urban biodiversity and provide habitats for urban wildlife, thereby maximizing the societal benefits.