Urban Ecosystems最新文献

Urbanization and fragmentation of habitat are major drivers of population declines in wildlife in cities. This study evaluated fragmentation of aquatic systems in the context of urbanization, using the Eastern long-necked turtle Chelodina longicollis as a model as it is a generalist species, highly vagile and engages in regular overland migration. During two seasons (2020-22), we compared C. longicollis demography in stormwater ponds in two distinct urban drainages, one with greater habitat connectivity (lower road network and an unmodified creek) and one with lower habitat connectivity (higher road network and stormwater drains) in Canberra, south-eastern Australia. Most of the parameters related to habitat (pond age and size) and food requirements (phosphate and prey biomass) for C. longicollis were similar between the two drainages, in addition to proportion of females, overall size-frequency distributions and population size (corrected for variation in capture probability). However, there was a significant effect of the interaction between pond habitat connectivity and pond size with population sizes increasing more steeply in higher than in lower connectivity sites (F_{1, 4} = 14.3, p = 0.02). We also recaptured a marked turtle from a previous study in the drainage with more habitat connectivity, 14 years later and 15 km from its initial point of capture. This demonstrates the ability of the species to move within an urbanized context. Despite evidence of C. longicollis being resilient to urbanization, dispersal constraints seem to affect population dynamics and long term population viability in areas with low habitat connectivity.

Urbanization has increased wealth disparity within the United States, impacting the urban landscape and species interactions. In particular, the interactions between street trees and the arthropod communities that live among them may be modified by both human population densities across urban to suburban locations, as well as income levels within these areas. We examined the effect of land use type (urban vs. suburban) and median household income on variation in leaf damage and arthropod abundance of red maples (Acer rubrum) in the District of Columbia metropolitan region. We compared these levels of leaf damage to rates observed in a nearby temperate deciduous forest. We predicted leaf damage would be positively correlated with urbanization (forested < suburban < urban) and negatively correlated with neighborhood income level (low > medium > high). Instead, we observed higher levels of leaf damage on trees in the forest environment compared to the urban and suburban areas. Leaves from urban medium and high-income areas were less likely to exhibit herbivore damage than those from suburban areas. Of the leaves with damage, those in urban high-income and suburban low-income areas exhibited the most leaf area missing. These trends may be related to specific factors associated with urbanization and income level, such as impervious surface coverage and tree coverage. This study highlights differences in biotic interactions across individual neighborhoods and the importance of including socio-economic variables when examining species interactions in urban environments.

Urban areas are growing rapidly across the globe. Such environments present specific challenges to wildlife. Resources can be highly fragmented in space and time, accompanied by specific risks and opportunities that can emerge from proximity with humans. Overall, these have been shown to lead to specific activity patterns in wildlife, which tend to restrict their space use accordingly to avoid encounters with humans. Yet, some foraging opportunities supplied by humans can also attract wildlife. Urban-dwelling species would therefore benefit from learning when and where to exploit human derived food. Here, we investigate how birds exploit areas of different degrees of urbanization and if they do so with specific time patterns. We used the example of feeding sulphur-crested cockatoos (Cacatua galerita) in Sydney, Australia. We combined tracking birds to identify key resources, and a citizen science approach to investigate human-wildlife interactions in the urban landscape. Our data suggest that SCC do not use all parts of their home range equally, but use green spaces as roosting and foraging areas, while facultatively using more urbanized areas at specific times when they are the most rewarding. This implies a role for sophisticated time and place learning, with birds matching activity to human patterns. This study builds on the literature investigating human-animal interactions, expanding our understanding of animals’ exploitation of human behavior. Our results highlight the unique opportunity that studies on urban wildlife have for understanding urban biodiversity establishment, maintenance, and cognitive ecology.

Urban ecosystems are suitable for the introduction and spread of alien bird species, and early detection of their establishment and expansion is crucial to reduce potential negative impacts. In this context, the use of opportunistic citizen science data can have considerable advantages in relation to conventional scientific approaches. We gathered records of parakeets and parrots (Psittaciformes) and mynas and starlings (Sturnidae) for the urban area of Lisbon (Portugal) from the eBird database. We used this opportunistic citizen science data to document the establishment and expansion and to estimate distribution trends of alien bird species in urban ecosystems. In the last decade there has been a considerable increase in the amount of opportunistic citizen science data available in eBird for our study area. The probability of presence of the Senegal parrot, rose-ringed parakeet, blue-crowned parakeet, and crested myna was positively influenced by the number of lists. For the rose-ringed parakeet, blue-crowned parakeet, and crested myna, the year positively influenced the probability of presence, suggesting an increase in distribution range. We observed that spatio-temporal variations in effort associated to opportunistic citizen science data sources may generate bias in trend estimates, and therefore we recommend the effort should always be accounted for. Our approach agreed with the documented expansion of alien bird species in the study area, supporting the potential usefulness of opportunistic citizen science in providing early detection on biological invasions in urban ecosystems, particularly where this is the best or the only source of information available.

Around the globe, ecological restoration projects are being undertaken to mitigate anthropogenic impacts and recover lost biodiversity; however, evaluations of efficacy can lack robustness or, more often, are not completed at all. In this perspective piece, to demonstrate the utility of acoustic telemetry to assess ecological restoration in aquatic systems, we synthesize two case studies in coastal freshwater and marine urban ecosystems: Toronto, Canada, and Bergen, Norway. In Toronto Harbour, a Before-After-Control-Impact experimental design was instrumental in detecting differences attributed to ecological restoration across multiple species of fish. Additionally, acoustic telemetry data were paired with catch and community traits derived from electrofishing, which provided a more complete understanding of fish responses to restoration. In Bergen Harbour, the acoustic telemetry array was deployed before restoration, providing a Before-After comparison of habitat use by several fish species and European lobster (Homarus gammarus). In addition to acoustic telemetry, blood samples were taken from multiple fishes, to examine the levels of contaminants before and after restoration, adding an ecotoxicological dimension to the assessment. Incorporating these complementary methods contributed to a more holistic understanding of animal response to ecological restoration. Finally, we also identified indicators that could be calculated using acoustic telemetry data, including those derived from addition sensors (e.g., pressure). As we look to the future within the Anthropocene, it will be imperative that ecological restoration achieves intended goals and we contend that acoustic telemetry has a bigger role to play in the evaluation of efficacy as it provides continuous monitoring compared to more traditional, discrete sampling.

Urbanization has important effects on the distribution and persistence of wildlife communities. Urbanization may alter not just the distributions of individual species, but also co-occurrence patterns and thus the potential for interspecific interactions (e.g., competition, predation) that structure wildlife communities. Little is currently known about how urbanization alters species co-occurrence or how these changes shape urban species assemblages. Using tree squirrels as a model functional group, we quantified how urbanization alters species occurrence and co-occurrence patterns to shape species assemblages, and how these effects vary within and among cities. We constructed a multi-species, multi-season occupancy model to identify relationships between tree squirrel occupancy and co-occurrence and local land and tree canopy cover and examined variation in these relationships within and among nine US cities. Species’ responses to canopy cover were highly variable among, but less variable within cities, suggesting that even common urban wildlife species may respond differently to urban intensity in different landscape contexts. Species co-occurrence was also highly variable among cities and weakly related to canopy cover within a city. These findings provide important evidence that both environmental attributes and species interactions shape urban wildlife communities. Important for management and conservation, they suggest that tree-canopy cover can particularly support forest species co-occurrence and that managing urban forests to provide high canopy cover could contribute to the diversity of urban wildlife communities in forested ecoregions.

In urban and suburban areas, wildlife and people are often in close quarters, leading to human-wildlife interactions (HWI). Understanding how wildlife interacts with humans and the built environment is critical as urbanization contributes to habitat change and fragmentation globally. The environmental drivers that influence HWIs are largely unknown in some systems, however, especially across multiple spatial scales. Using location and species data from a business that relocates snakes across the Phoenix metropolitan area (Arizona, USA), we found the most frequently removed were venomous (family Viperidae, e.g., rattlesnakes). Nonvenomous snakes were also removed (family Colubridae, e.g., gophersnakes). Using these records, we investigated taxa-specific habitat relationships at two spatial scales. The neighborhood scale focused on front yard measures of cover and vegetation classes, and the landscape scale focused on remote-sensed variables related to vegetation indices and degree of urbanization. Both analyses compared areas where snakes were removed to random locations in the city to evaluate used and available locations of snakes. At the neighborhood scale, snake removals (n = 59) occurred in yards with abundant vegetation and debris cover opportunities compared to random locations. At the landscape scale, snake removal locations (n = 764) had taxa-specific differences, with nonvenomous snakes removed from areas of higher urbanization than venomous snakes, a pattern was likely related to differences in life history and behavior. Environmental variables associated with HWI can vary across different spatial scales. Understanding these environmental characteristics associated with snake removals from residential can focus management activities to reduce potential human-snake conflict.

In an increasingly urbanized world, some raptors successfully colonize and thrive in urban environments, leading to more frequent interactions with humans. These interactions can be either positive, such as providing ecosystem services, or negative, resulting in human-wildlife conflicts. Despite growing literature on these interactions, a comprehensive review focusing on urban environments has been lacking. This study aimed to address this gap by conducting a systematic review using Google Scholar and the Scopus bibliographic database. A total of 45 studies met the search criteria, with a predominant prevalence of the northern hemisphere. Accipitriformes was the most studied order of raptors (50%), followed by Strigiformes (37%), Falconiformes (8%), and Cathartiformes (2%). Positive interactions studied included cultural services, pest control, positive perception, carrion removal, while negative interactions involved safety damage, property damage, negative perception, disease transmission, livestock damage, nuisance and superstitions. Pest control and cultural services were supported by the evidence, although only for specific orders. Carrion removal and aggressiveness appear to decrease with urbanization, although more studies are needed to verify this premise. Both positive and negative perceptions were evident, influenced in part by the knowledge or closeness that people had towards urban raptors. We discuss how the interactions studied influence the daily lives of citizens and, in turn, how human activities shape and influence these interactions. Finally, given that cities are socio-ecological systems, we advocate for methodologies that integrate the social aspects of human-predator interactions along with ecological ones to promote coexistence.

The rapid decline in avifauna populations across North America underscores the urgency of implementing effective conservation strategies. While waterfowl species have generally increased in abundance due to investments in habitat restoration and species management, most other waterbird species have declined. In contrast to the widespread decline of natural habitat for waterbirds, urban greenspaces have proliferated. However, the extent to which urban greenspaces provide habitat for waterbirds is largely unknown. We measured waterbird abundance in Forest Park, Saint Louis, which contains a large expanse of restored waterways. Between 2020 and 2022, we used point counts to quantify alpha and beta diversity of waterbirds across five waterbodies. We also quantified several environmental factors hypothesized to influence waterbird presence including weather, bathymetry, water quality, and prey abundance. We assessed environmental drivers of alpha and gamma diversity using generalized linear mixed models, and beta diversity with Jaccard’s similarity indices and Mantel tests. Water depth and depth heterogeneity were the strongest determinants of alpha diversity. Measured environmental variables did not predict beta diversity but improved model fit when testing gamma diversity. Forest Park is a regionally important urban habitat for waterbirds, hosting 62% (38 species) of the total regional species pool, including nine species of conservation concern and two state endangered species. Urban parks can contribute to waterbird conservation despite habitat loss elsewhere if park managers prioritize habitat restoration. In addition to the total area of waterways, water depth and water depth homogeneity are important considerations to maximize waterbird species diversity in urban greenspaces.