Breeding performance of an apex predator,the peregrine falcon,across urban and rural landscapes

Urban environments present wildlife with major challenges and yet surprising numbers of species have colonised towns and cities globally. Despite the growing realisation that urban centres can be important habitats for wildlife, why some species do better than others in urban environments remains poorly understood. Here, we compare the breeding performance of an apex predator, the peregrine falcon (Falco peregrinus), in urban and rural environments, and test whether variation in reproductive success between and within environments is driven by prey. Historical breeding data were collected from raptor study groups across Great Britain between 2006 and 2016, from 22 urban and 58 rural nest sites, involving 101 and 326 nesting attempts, respectively. Prey density, biomass and diversity around the individual nests was estimated using modelled estimates from a national bird census. Urban peregrines produced more fledglings and had a higher overall nesting success (i.e. whether a nesting attempt was successful or unsuccessful) than rural peregrines. Prey density and biomass were significantly higher, and diversity significantly lower, in the urban sites, and explained the variation in reproductive success within both the urban and rural environments. Therefore, urban environments in Great Britain appear to provide peregrine falcons with superior habitats in terms of prey availability compared to rural habitats. We conclude that some apex predators can benefit from urban environments and that urban planning has the potential to benefit biodiversity across many trophic levels.

     

Aspects of the ecology and behaviour of a potential urban exploiter,the southern tree agama,Acanthocercus atricollis

Urbanisation has caused significant alterations to ecosystems, generally resulting in decreased biodiversity. However, certain animal species persist and thrive in urban environments by making use of available opportunities, anthropogenic resources, infrastructure and increased ambient and surface temperatures. These species are known as urban exploiters. We investigated the southern tree agama, Acanthocercus atricollis population trends, habitat use and basking and shading behaviour in a high-density urban human-populated housing metropolitan area in Pietermaritzburg, KwaZulu-Natal, South Africa. We marked individual southern tree agamas to determine habitat use and territories (n?=?37). The southern tree agama population density was high, and they had established set territories here. We conducted monthly observations (February 2017–July 2017 and March 2018–February 2019) to determine the degree of basking and shading behaviour with season and time of day and location. Southern tree agamas invested more than half of their time (57%) in basking behaviour during the overall observational study period. Basking and shading patterns changed with season and time of day. The number of basking southern tree agamas decreased during winter and basking commenced later. We found that increased anthropogenic infrastructure and supplementary food availability, decreased predators, and basking opportunities could have had an influence on their population increase and that the southern tree agama is a potential urban exploiter.

     

Urban open spaces from a dispersal perspective: lessons from an individual-based model approach to assess the effects of landscape patterns on the viability of wildlife populations

Green areas drawn on a city plan represent open spaces that have different meanings for humans and wildlife. Diverse kinds of green may influence species viability in urban environments. It is necessary to understand what those areas mean for wildlife populations and how land-use changes affect habitats and movements for making scientifically defensible planning and design decisions. My objective was to demonstrate how open space and urban development patterns affect the viability of wildlife populations in urbanizing landscapes from a movements perspective. Eight scenarios for 2060 for an urbanizing area near Portland, Oregon combined four open space (none, corridors, parks, and network) with two urban development patterns (compact and dispersed). Dispersal model HexSim simulated three target species – Red-legged frog (Rana aurora aurora), Western meadowlark (Sturnella neclecta) and Douglas squirrel (Tamasciurus douglasii) – movements on those scenarios to compare and contrast sustained populations to the ca. 2010 baseline landscape. Network scenarios presented the largest number of frog breeders. Greenway scenarios showed the largest populations of squirrels. Park and network scenarios sustained viable populations of meadowlarks, but park scenarios performed best. Compact development scenarios performed best for most indicators, while dispersed development scenarios performed better for meadowlarks. Network scenarios performed best when considering the collective of species. Networks presented more diverse habitats, sustaining higher diversity of species. For plans to sustain more species, more comprehensive and diverse habitats must be promoted, otherwise trade-offs should be expected – like the extinction of meadowlarks in greenway scenarios.

     

Vertical segregation by breeding ring-necked parakeets <Emphasis Type="Italic">Psittacula krameri</Emphasis> in northern Italy

Cavities represent a limiting resource for breeding birds, thus triggering potential competition, mostly in urban ecosystems. The ring-necked parakeet Psittacula krameri is one of the main alien invasive bird species of the world. Introduced populations are reported for over 35 countries, Italy included. This parakeet mainly depends on trunk cavities for reproduction but, occasionally, it may nest within building holes. A growing population of this species is present in the urban area of Pavia (northern Italy). Differently, from what has been observed in other colonies of the global introduced range, most of this urban population nests within the putlog holes of the Visconti castle and surrounding towers, together with four native species. In this work, we counted the breeding pairs of ring-necked parakeets nesting within putlog holes of castle and tower walls and estimated the breeding population size. Observations were carried out once a week, 30 min before sunset, for an hour, from the start of April to the end of August 2016 and 2017. We assessed whether a vertical segregation occurred between parakeets and native species (i.e. the rock pigeon, the jackdaw, the Italian sparrow and the common swift) through a dissimilarity index. Inter-specific interactions have never been observed, despite two pigeon ticks being detected on rescued parakeets. A strong vertical segregation was observed between ring-necked parakeets and pigeons, and between ring-necked parakeets and common swifts. Ring-necked parakeets and jackdaws were mostly observed in the highest putlog holes. No breeding parakeet pair was observed within plain trunk cavities in the surroundings of the castle walls, which were instead occupied by jackdaws and tawny owls. Most parakeet nests were located on the eastern wall, where they receive the first light at dawn.     

Native and exotic species in the urban landscape of the city of Rio de Janeiro,Brazil: density,richness, and arboreal deficit

Shaped by European influences, the Brazilian urban landscape was marked by the predominant use of exotic species in planted areas. In the 19th century along the city streets of Rio de Janeiro, trees were planted at a standard distance from each other. With time, native species began to be used in the urban landscape. Our purpose was to evaluate the utilization of exotic plant species in the urban landscape of Rio de Janeiro, evaluate the city’s arboreal deficit, and relate its neighborhood arboreal density to its economic index. Arboreal deficit represents the negative difference between the total number of expected trees and the observed number in the streets based in the standard distance used in the past. Twenty native and 40 exotic species were found in the 1701 streets sampled. A high percent of streets did not have any planted trees and the number of trees was greater in wealthier neighborhoods. The strong prevalence of exotic species is indicative of the negative impact of human activity on the biota. Since the municipality of Rio de Janeiro harbors forested areas, the risk for dissemination of exotic species is high.     

Colonization and habitat selection of a declining farmland species in urban areas

Despite the accelerating global urbanization and its associated implications for wildlife and humans, we know little about the biology of urban ecosystems. Here, we investigated colonization and habitat selection of the European hare (Lepus europaeus), a declining farmland species, in urban areas in Denmark, using a combination of citizen science data and transect counts. Further, we estimated the population density of urban hares in Aarhus, Denmark’s second largest city. Our results provide the first evidence that hares have established populations in urban areas, potentially in response to decreasing habitat quality in rural areas due to agricultural intensification. The hare density in Aarhus was ca. 8 hares per km², which is comparable to or slightly higher than hare abundance estimates from various pastural areas in Europe, suggesting that urban areas provide suitable habitat for hares. Hare habitat selection was generally associated with areas consisting of large lawns, such as high buildings and parks, which potentially provide high-quality forage throughout the year. Considering the increasing expansion of urban areas and deteriorating habitat quality of agricultural areas, urban planning that incorporates habitat requirements for wildlife could help to support urban animal populations, especially for species of conservation concern.

     

Nest design in a changing world: Great tit <Emphasis Type="Italic">Parus major</Emphasis> nests from a Mediterranean city environment as a case study

Investigations of urbanization effects on birds have focused mainly on breeding traits expressed after the nest-building stage (e.g. first-egg date, clutch size, breeding success, and offspring characteristics). Urban studies largely ignored how and why the aspects of nest building might be associated with the degree of urbanization. As urban environments are expected to present novel environmental changes relative to rural environments, it is important to evaluate how nest-building behavior is impacted by vegetation modifications associated with urbanization. To examine nest design in a Mediterranean city environment, we allowed urban great tits (Parus major) to breed in nest boxes in areas that differed in local vegetation cover. We found that different measures of nest size or mass were not associated with vegetation cover. In particular, nests located adjacent to streets with lower vegetation cover were not smaller or lighter than nests in parks with higher vegetation cover. Nests adjacent to streets contained more pine needles than nests in parks. In addition, in nests adjacent to streets, nests from boxes attached to pine trees contained more pine needles than nests from boxes attached to other trees. We suggest that urban-related alterations in vegetation cover do not directly impose physical limits on nest size in species that are opportunistic in the selection of nesting material. However, nest composition as reflected in the use of pine needles was clearly affected by habitat type and the planted tree species present, which implies that rapid habitat change impacts nest composition. We do not exclude that urbanization might impact other aspects of nest building behaviour not covered in our study (e.g. costs of searching for nest material), and that the strengths of the associations between urbanization and nest structures might differ among study populations or species.     

Relationship between urbanization and bat community structure in national parks of the southeastern U.S.

Urbanization and development are predicted to increase considerably in the United States over the next several decades, and this is expected to result in large-scale habitat loss, fragmentation and loss of wildlife species. Thus, natural parks and preserves are becomingly increasingly important in the conservation of regional biodiversity. We used mist-nets and AnabatII acoustic detectors to survey bats in 10 national parks in the southeastern U.S. and examined the relationship between bat community structure and development in the surrounding 5 km. We predicted that species richness would increase with park size and that species richness and evenness would decrease with development. Species richness was not related to development or any other landscape characteristics including park size. In contrast, species evenness declined with increasing development. Percent Developed land in the surrounding 5 km area was the only variable that entered into the stepwise regression model. The decrease in species evenness in the urban parks was due to the dominance of big brown bats (Eptesicus fuscus) in these parks. The percentage of big brown bats in our captures was positively related to percent Developed land in the surrounding area. Our data suggest that urban parks may be important for conserving regional bat biodiversity. However, the low species evenness in these parks suggests that some bat species may be susceptible to the effects of urbanization and may be extirpated over time. Thus, management of urban as well as rural parks should strive to conserve as much bat roosting and foraging habitat as possible.     

Contrasting effects of urbanization on arboreal and ground-dwelling land snails: role of trophic interactions and habitat fragmentation

Urbanization generally reduces wildlife populations. Individual species responses, however, are often highly variable, and such variability can be explained by differences in species ecological traits. To examine this hypothesis, we focused on two co-occurring land snails, Ezohelix gainesi and Euhadra brandtii sapporo; the former is ground-dwelling and the latter is arboreal. We first estimated their population densities at nine sites distributed along an urbanization gradient: three were located in continuous natural forests, three at the edge of natural forests, and the rest in small isolated forests in urban areas. As a result, the ground-dwelling E. gainesi occurred at highest density in urban forests, followed by forest edges and continuous forests. By contrast, the arboreal E. b. sapporo occurred at highest density in continuous forests, but declined in forest edges and urban forests. We then conducted manipulative field experiments to quantify changes in predation pressure on these species. Ground-tethered E. gainesi and E. b. sapporo were repeatedly predated upon by forest-living mammals in continuous forests, but their survival rates increased in forest edges and urban forests. By contrast, canopy-tethered E. b. sapporo maintained high survival rates in all three forest types. The results indicate that a lack of mammalian predators enables ground-dwelling species to occur at high densities in urban forests, whereas the arboreal species was not affected by this predator relaxation effect. The combination of species-specific behavioural traits and changes in predator communities across an urbanization gradient has important effects on the biodiversity of urban ecosystems.

     

Effects of urban matrix on reproductive performance of Great Tit (Parus major) in urban woodlands

In urban areas the density of breeding tits (Paridae) is generally higher and reproductive performance lower compared to rural areas. To explain these landscape differences several hypotheses have been proposed, e.g. differences in habitat quality, inter- and intra-specific competition, predation and food abundance. How breeding performance of birds within remnants of natural vegetation in urban areas is affected by adjacent matrix has been less studied. We performed an experimental study in four urban woodlands surrounded by three types of habitat matrix: residential, high-rise building and grassland/golf course. We placed 300 nest boxes for tits (great tit Parus major and blue tit Cyanistes caeruleus) in 15 transects that were 200 m long, extending from the adjacent matrix 150 m into urban woodland. Density of breeding great tit pairs was highest in residential areas and hatch date was earlier in the residential habitat compared to the other two habitats, however, nestling condition was lower in residential areas. Hatching date was earlier but hatching spread (heaviest nestling/lightest nestling) higher in the three types of urban matrix than inside the urban woodlands. In contrast to previous large-scale comparisons of urban and rural matrix, we almost exclusively found differences in qualitative measures (nestling condition and hatchling spread) at the small scale in which this study was conducted. Adjacent matrix affect great tits breeding in remnant urban woodlands, thus we suggest that management of the surrounding matrix should be included in conservation plans for urban woodlands.     

Effects of human-related disturbance on breeding success of urban and non-urban blue tits (<Emphasis Type="Italic">Cyanistes caeruleus</Emphasis>)

There is a need to study the effects of urbanization on wildlife in order to understand the ecological implications of increasing urbanization and find out how to reduce its threats to biodiversity. The blue tit evolved as a forest species and prefers deciduous and mixed forests, whereas its nesting in urban habitats is a more recent phenomenon. Our long-term study of blue tit populations has been conducted in two habitats: an urban parkland (frequently visited by people) and a deciduous forest outside of the city. Using linear mixed modeling, we revealed that a relationship of blue tit breeding success (and the number of fledglings) with thermal conditions in May differed between the urban parkland and the forest. While the relationship was positive in the forest, it was negative in the parkland. In addition, breeding success in the parkland increased with increasing number of rainy days in May. We argue that the main possible reason for such patterns is human activity in the parkland, which interferes with tit parental care, especially the regular feeding of nestlings, whereas it is evidently associated with weather conditions. Human disturbance in the forest is likely to be negligible.     

Variation in breeding parameters of the Australian magpie Gymnorhina tibicen in suburban and rural environments

The breeding ecology of the Australian magpie Gymnorhina tibicen in suburban and rural areas was compared as part of a study into the synanthropy of the species in southeast Queensland, Australia. During the two years of the study suburban magpies were found to have significantly advanced breeding dates compared to rural magpies. Suburban magpies typically re-nested when an initial nest failed, although this did not result in greater productivity than that of the rural magpies. Suburban magpies had similar mean numbers of young per breeding pair; they also showed higher mortality between fledging and a final count in February. This study suggests that introduced predators and deaths due to motor vehicles may account for this mortality in suburban areas. Anthropogenic factors present within suburban areas such as the watering of lawns and the widespread provision of food for wildlife are likely to play an important role in the differences in the timing of breeding. In addition, temperature may also have an inhibitory effect on the onset of breeding, an influence lessened in the suburban areas due to higher temperatures.     

Population viability assessment and sensitivity analysis as a management tool for the peri-urban environment

Anthropogenic disturbance occurring within urban ecosystems is often extreme and highly variable. A quantifiable measure of their effect on the persistence of urban wildlife populations would contribute to conservation efforts. This study suggests that population viability assessment, a commonly utilized modeling tool for creating management strategies for rare and threatened wildlife populations, is also appropriate in an urban context. It can be used to create proactive management strategies that quantify the impacts of anthropogenic disturbances and rank a range of management options within an active adaptive framework. To show this, population viability assessment and sensitivity analyses were run to forecast the population trends of a seemingly robust but isolated swamp wallaby (Wallabia bicolor) population living in peri-urban Sydney, Australia; a population exposed to anthropogenic disturbances from towns, hobby farms and roads. Modeling suggested this population was in a slow decline and that predictions were highly dependent upon stochastic events and the precision of reproduction rates. However, a number of management options are identified that will dramatically reduce the risk of total population decline, with complementary options utilized in tandem the most effective.     

Frugivory and habitat use by thrushes (Turdus spp.) in a suburban area in south Brazil

Thrushes (Turdus spp., Turdidae) are among the most common frugivorous birds in urban areas around the world, where they disperse the seeds of a variety of plant species. We studied the abundance, habitat use, foraging behavior and diet of four thrush species (Turdus rufiventris, T. amaurochalinus, T. leucomelas, and T. albicollis) in a suburban area in south Brazil. Abundance, habitat use and foraging behavior were based on birds surveyed along a 3,240 m transect crossing open (formed by lawns, streets, and buildings) and forested areas. Diet was based on fecal samples collected from mist-netted birds. Turdus rufiventris was the most abundant species, followed by T. amaurochalinus, T. leucomelas, and T. albicollis. All species used forest fragments more frequently than expected by chance. A total of 91.8% (n = 147) of the fecal samples contained fruit remains, while 42.2% contained only animal matter. Most of the foraging records were on the ground, where birds got mainly invertebrates. Fruits and invertebrates were eaten more frequently in open than in forested areas. A total of 25 seed morfospecies were found in the droppings, including five exotic plant species. Thrushes overlapped widely in the fruit composition of their diets. The high abundance and degree of frugivory, coupled with the frequent use of forest patches, indicate that thrushes are among the great bird contributors to the seed dispersal occurring in urban forest patches, potentially influencing the vegetation dynamics of such habitats so important for the maintenance of the biodiversity in urban areas.     

The effects of urbanization on North American amphibian species: Identifying new directions for urban conservation

Urbanization is a pervasive and growing threat to amphibian populations globally. Although the number of studies is increasing, many aspects of basic amphibian biology have not been investigated in urban settings. We reviewed 32 urban studies from North America and quantified the number of species studied and their response to urbanization. We examined existing research on breeding habitats, life-history stages, movement patterns, and habitat use relative to urbanization. We found amphibians as a whole respond negatively to urbanization (69 reported responses were negative, 6 were positive and 35 showed no effect). We caution, however, that many North American species still lack or are associated with conflicting information regarding species-specific responses (e.g., 89 potential responses were unknown). Approximately 40% of all anuran and 14% of caudate species in North America were investigated in the literature; however, the most diverse genera (e.g., Plethodon and Eurycea) were the most understudied likely due to their cryptic terrestrial lifestyles and biases in sampling protocols that assess wetland habitats via call surveys. Research on movement and small scale habitat use was deficient. Adult, juvenile, tadpole, and egg mass life-history stages commonly served as direct measures of species presence and abundance; however, such data do not accurately reflect recruitment into subsequent age classes and population persistence. The lack of data on many North American species may be contributing to poor management of urban amphibian populations and their habitats.     

Animal behavior in urban ecosystems: Modifications due to human-induced stress

Wildlife-human interactions are increasing in prevalence as urban sprawl continues to encroach into rural areas. Once considered to be unsuitable habitat for most wildlife species, urban/suburban areas now host an array of wildlife populations, many of which were previously restricted to rural or pristine habitats. The presence of some wildlife species in close proximity to dense human populations can create conflict, forcing resource managers to address issues relating to urban wildlife. However, evidence suggests that wildlife residing in urban areas may not exhibit the same life history traits as their rural counterparts because of adaptation to human-induced stresses. This creates difficulty for biologists or managers that must address problems associated with urban wildlife. Population control or mitigation efforts aimed at urban wildlife require detailed knowledge of the habits of wildlife populations in urban areas. This paper describes the history of wildlife in urban areas, provides examples of wildlife populations that have modified their behavior as an adaptation to urban stresses, and discusses the challenges that resource managers face when dealing with urban wildlife.     

Factors related to tree growth across urban-rural gradients in the Midwest,USA

Several environmental factors influence tree growth at any site. The objective of this study was to examine the relationship between biotic and abiotic factors and tree growth rate (mean ring width averaged over the last 10 years) in settings ranging from urban to rural. Six clusters, each with five communities and two rural parks, were sampled in Illinois, Iowa, Minnesota, Missouri, and Wisconsin, for a total sample of 320 trees. Within each community, trees in parks, and along residential and commercial streets were sampled. Five species were sampled: silver maple (Acer saccharinum L.), honeylocust, (Gleditisia triacanthos L.), hackberry (Celtis occidentalis L.), black maple (Acer nigrum Michx F.), and basswood (Tilia americana L.). Factors were investigated for three scenarios: (i) all trees sampled in all clusters, (ii) a single species, all clusters, and (iii) all species, a single cluster.Baseline variables (cluster, place population, site, species, and age) accounted for 49–71% of observed variation in growth rate. Combined biotic factors accounted for 5 to 6% of observed variation. For all species in a single cluster, combined abiotic factors accounted for 11% of observed variation. Biotic factors related to growth rate detected using multivariate analyses included number of other trees within 9 m, presence of disease and insects, and human-induced mechanical injury. Abiotic factors that were related to tree growth included presence of pavement and core bulk density. For trees in rural parks, number of other trees within 20 m, and for trees in both rural and community parks, number of other trees within 9 m of sample trees were associated with decreased growth rate.     

Mammal conservation in a changing world: can urban gardens play a role?

Urbanisation threatens biodiversity globally, yet some animal populations persist within urban landscapes. Conservation of urban wildlife has prioritised parks and remnant bushland as critical habitat and neglected the role that residential gardens offer for conservation. We explored the potential for residential gardens to assist the conservation of mammals using an online questionnaire administered to residents of two case study cities in Australia to identify how widespread mammals in cities can be, which garden features promote mammal presence, and if the features varied among species with different habitat requirements. From 649 responses we found that three mammal species with different habitat requirements occurred in residential gardens throughout the city landscape. Garden features promoting mammal presence were consistent with broad ecological and habitat requirements of each species, but differed among both species and regions. Our study demonstrates that residential gardens offer a valuable habitat for mammals, and that garden features could be manipulated to promote use of gardens by these species. By considering gardens in urban planning and management actions aimed at conserving urban wildlife, residential gardens offer additional habitat to parks, roadside vegetation and urban bushland, and can play a significant role in biodiversity conservation.

     

Habitat selection by an avian top predator in the tropical megacity of Delhi: human activities and socio-religious practices as prey-facilitating tools

Research in urban ecology is growing rapidly in response to the exponential growth of the urban environment. However, few studies have focused on tropical megacities, and on the interplay between predators’ habitat selection and human socio-economic aspects, which may mediate their resilience and coexistence with humans. We examined mechanisms of breeding habitat selection by a synanthropic raptor, the Black Kite Milvus migrans, in Delhi (India) where kites mainly subsist on: (1) human refuse and its associated prey-fauna, and (2) ritualised feeding of kites, particularly practised by Muslims. We used mixed effects models to test the effect of urban habitat configuration and human practices on habitat selection, site occupancy and breeding success. Kite habitat decisions, territory occupancy and breeding success were tightly enmeshed with human activities: kites preferred areas with high human density, poor waste management and a road configuration that facilitated better access to resources provided by humans, in particular to Muslim colonies that provided ritual subsidies. Furthermore, kites bred at ‘clean’ sites with less human refuse only when close to Muslim colonies, suggesting that the proximity to ritual-feeding sites modulated the suitability of other habitats. Rather than a nuisance to avoid, as previously portrayed, humans were a keenly-targeted foraging resource, which tied a predator’s distribution to human activities, politics, history, socio-economics and urban planning at multiple spatio-temporal scales. Many synurbic species may exploit humans in more subtle and direct ways than was previously assumed, but uncovering them will require greater integration of human socio-cultural estimates in urban ecological research.

     

Raptor nesting locations along an urban density gradient in the Great Basin,USA

Raptors are the most prevalent group of urban apex predators, and the majority of raptor genera in North America have been recorded using urban areas. Prior research assessments along urban-wildland gradients show that urban habitat preference varies by raptor species and that raptor nesting preferences within urban settings may vary. Attempts to understand the intra- and inter-specific nesting patterns along an urban gradient would advance extant knowledge. Here we present the locations of individual nest sites of nine raptor species along an urban gradient in Reno-Sparks, NV. We developed an urban density model based on the number of residents, number of employees, and building footprints and number of floors for built structures within each land parcel at four spatial scales, representing nest site, macrohabitat, average nearest-nest, and landscape scales. Cooper’s Hawks (Accipiter cooperii), Sharp-shinned Hawks (Accipiter striatus), and Red-tailed Hawks (Buteo jamaicensis) nested across the widest range of the urban spectrum and closest to the urban core, whereas Golden Eagles (Aquila chrysaetos) and Swainson’s Hawks (Buteo swainsonii) nested on the urban fringe. Urban density for all nest locations was lowest at the nest-site scale, and the highest at the average nearest-nest and landscape scales. Raptors tended to occupy a wide range of the building-area density spectrum but not the building-height or employee density spectrums indicative of the attractiveness of suburban habitat.