Assessing the effect of developed habitat on waterbird behaviour in an urban riparian system in Ottawa,Canada

Waterbird species were used to assess the consequences of developed habitat on wildlife behaviour in an urban riparian system along the Rideau River in Ottawa, Canada. Fourteen developed sites and 14 undeveloped sites were surveyed from October 2004 to February 2005. Each site was approached on foot and the first observed behaviour (i.e., fleeing, foraging, resting or swimming) of each individual was recorded. A total of 10,604 behavioural observations were made across 12 taxa. Overall, the fleeing behaviour was observed more often at undeveloped sites. Foraging, resting and swimming behaviours were observed more often at developed sites. We found that seven species fled more often at undeveloped sites, including hooded merganser. This species was also more abundant at undeveloped sites, suggesting that hooded merganser may be more sensitive to anthropogenic disturbance in urban environments than other species that are habituated toward humans. For sensitive species, undeveloped shoreline may serve as a refuge from human disturbance in urban ecosystems.     

The influence of anthropogenic resources on multi-scale habitat selection by raccoons

With the continuing spread of urban areas, gaining a greater understanding of the effect of human presence on wildlife species is essential for wildlife managers. We determined the influence of anthropogenic resources on home range size and habitat selection of raccoons (Procyon lotor) during summer (June–August) 1996–2000 for 120 raccoons at three sites exposed to varying levels of urbanization and anthropogenic resources, specifically food. Home range estimates were larger (P < 0.05) at the rural site than the suburban and urban sites for both genders. We used compositional analysis to examine raccoon habitat selection at the second-order home range, second-order core area, and third-order home range scales. Woodland was consistently a highly-selected habitat type for both sexes at every spatial scale. Relative to other habitat types, habitat associated with human-related food (human use areas) was selected most often at the urban site, intermediately at the suburban site, and not selected at the rural site. Spatial scale also affected habitat selection. Human use areas were preferentially selected at the second- and third-order level at the urban site, third-order level only at the suburban site, and at neither level at the rural site. Additionally, intersexual differences in habitat selection were reduced at the urban site, with both sexes preferentially selecting for human use areas as well as woodland habitat. Smaller home ranges in urbanized environments are often attributed to the abundant and concentrated anthropogenic resources associated with human activity, but with little empirical support. Our habitat selection analyses followed our predictions that raccoon foraging is strongly influenced by the artificial distribution and abundance of human-related food. Male and female raccoons in urban areas reduce their foraging patterns and focus their foraging activity on anthropogenic foods.     

Juggling a “junk-food” diet: responses of an urban bird to fluctuating anthropogenic-food availability

Within highly urban systems, anthropogenic activity often fluctuates cyclically, e.g. between weekdays and weekends. Thus, urban species may regularly experience significant changes in human activity and anthropogenic food abundance over very short time scales. Knowledge of how urban birds cope with such fluctuations may improve our understanding of how some species exploit and thrive in urbanised habitats. In this study, we explore the consequences of highly fluctuating anthropogenic food for Red-winged Starlings Onychognathus morio at the University of Cape Town campus, South Africa. Here, high numbers of students (and therefore anthropogenic food resources) are present during weekdays in term time (high human presence “HHP” days). However, students are largely absent and food outlets closed during weekends and vacation periods (“LHP” days). Using focal observations and morning and evening weights of habituated colour-ringed starlings during the non-breeding season, we investigated how diet, behaviour and daily mass gain differed between HHP and LHP days. We hypothesised that anthropogenic food supply is beneficial to this city-dwelling species. We predicted that on HHP days starlings would consume overall more food and a greater proportion of anthropogenic food items, resulting in less time spent foraging and greater daily mass gain compared to LHP days. We found that on HHP days, starlings consumed more anthropogenic food, however overall food intake, and time budgets were similar to LHP days. Additionally, there was an indication that mass gain was greater on HHP days. Thus, starlings appear to cope with potential food shortage on LHP days by including more natural items in their diet.

     

Impact of urban structure on avian diversity along the Truckee River, USA

Urban riparian habitats are potentially important resources for native birds in arid ecosystems. Most studies have assessed the value of urban riparian habitat in terms of vegetation and natural resources; however, the surrounding land use and infrastructure may determine the viability of urban habitat. We studied the impact of urban structure, the combination of land use, infrastructure and vegetation variables that work together to shape the urban environment, on avian riparian habitat in the Truckee Meadows, Nevada, USA. Land use and infrastructure explained avian species richness and abundance better than local vegetation alone, but community resemblance was more strongly correlated to vegetation. Avian species guilds responded differentially to surrounding land use, suggesting there may be a functional difference between land use types. The best models for bird diversity used urban structure (both land use and vegetation) to describe potential habitat. Urban structure describes urban habitat in ways that vegetation variables alone cannot. Studies that ignore land use and infrastructure and other socioeconomic variables are likely missing key functional differences within urban ecosystems, and may miss the potential for compatible development that encourages both biodiversity and urban growth.     

Forest structure and anthropogenic disturbances regulate plant invasion in urban forests

Urban forest ecosystems, the structure, and functions therein are subjected to anthropogenic disturbances. Native and sensitive species from those forests might be lost due to such disturbances. At the same time, supplemented anthropogenic resources might create opportunities for exotic and invasive species. Although invasive species are considered one of the major threats to the urban biodiversity and ecosystems, the research on invasion dynamics in the Himalayas has primarily focused on the impacts of invasion on forest structure and productivity. This study aims to understand the influence of forest structure and anthropogenic factors in invasion success that are poorly covered in the existing literature. We selected 11 urban forest patches for the study considering the presence-absence of selected invasive species and structural attributes. We used Principal Component Analysis (PCA) to reduce co-linearity in the covariates and generalized linear mixed effects model (GLMM) to identify the factors affecting invasion success. We found that forest structural attributes, namely, tree diameter, height and canopy cover, and anthropogenic disturbances regulate invasion success in urban forests. This implies that maintaining urban forest structural attributes, especially the stands with large-sized trees, is essential to control invasion in the context of urbanization.

     

Ranging characteristics of the domestic cat (Felis catus) in an urban environment

In many countries, high densities of domestic cats (Felis catus) are found in urban habitats where they have the potential to exert considerable predation pressure on their prey. However, little is known of the ranging behaviour of cats in the UK. Twenty cats in suburban Reading, UK, were fitted with GPS trackers to quantify movement patterns. Cats were monitored during the summer and winter for an average of 6.8 24 h periods per season. Mean daily area ranged (95 % MCP) was 1.94 ha. Including all fixes, mean maximum area ranged was 6.88 ha. These are broadly comparable to those observed in urban areas in other countries. Daily area ranged was not affected by the cat’s sex or the season, but was significantly larger at night than during the day. There was no relationship between area ranged and habitat availability. Taking available habitat into account, cat ranging area contained significantly more garden and other green space than urban habitats. If cats were shown to be negatively affecting prey populations, one mitigation option for consideration in housing developments proposed near important wildlife sites would be to incorporate a ‘buffer zone’ in which cat ownership was not permitted. Absolute maximum daily area ranged by a cat in this study was 33.78 ha. This would correspond to an exclusory limit of approximately 300–400 m to minimise the negative effects of cat predation, but this may need to be larger if cat ranging behaviour is negatively affected by population density.     

Bird diversity in a subtropical South-American City: effects of noise levels,arborisation and human population density

Cities are highly modified environments in which the only areas that resemble natural landscapes are urban parks with low human population density. Attempts are frequently made to maintain high bird diversity in cities for aesthetic or educational reasons. However, it remains unclear whether local site characteristics are important in determining bird assemblage composition or whether simplification of the assemblage is an inevitable consequence of the changes associated with human population density. From May 1998 to December 1999, we undertook bird counts at 521 points in Porto Alegre, Rio Grande do Sul, southern Brazil. Our main goal was to understand the pattern of distribution of the bird species richness and density within the city and determine which variables most affect species assemblages. We recorded 132 species belonging to 43 families that are common in Rio Grande do Sul and obtained quantitative data on 121 species in survey sites. The two most abundant species (House Sparrow, Passer domesticus and Rock dove, Columba livia) were exotics. Analysis based on a reduced subset of 134 points surveyed in spring/early summer suggested that there was a North–south gradient in assemblage structure. Variation in assemblage structure was also affected by the number of trees, urban noise and human population density. However, human population density had a much smaller effect on richness and assemblage structure than variables subject to management, such as tree density and noise levels. These results suggest that complex communities may be maintained in densely populated urban areas of sub-tropical South-America given adequate urban planning.     

The abundance of yellow-legged gulls Larus michahellis breeding in the historic centre of Venice,Italy and the initial effects of the new waste collection policy on the population

The yellow-legged gull Larus michahellis has undergone widespread colonization of the urban environment in the recent past. The first urban breeding gulls were recorded in the historical centre of Venice, Italy, in 2000, and by 2005 there were already 24 roof-nesting pairs, with this number increasing significantly over the last decade. In 2016, a new door-to-door garbage collection system was introduced in Venice to prevent the accumulation of rubbish in the streets and limit the trophic resources available for the species. This study provides an up-to-date estimate of the Venice yellow-legged gull urban population using distance sampling method. We also studied the effect of the new waste collection system on the species by comparing the population estimate before (2017) and after (2018) the full implementation of this change and by analysing the trend of individuals collected in the old town by the wildlife recovery service during 2010–2018. Results estimated ca. 430 breeding pairs in June 2018 showing a 36% decrease with respect to 2017. We also found a decrease in the number of 1-year-old birds and pulli collected by the wildlife recovery service starting from 2016, when the policy implementation began. Our data did not show a significant decrease in the overall number of individuals, suggesting that the new policy has a stronger effect on the breeding success of the species than on adult survival. This study emphasizes the importance of preventing rubbish accumulation in the streets as factor for reducing the abundance of urban yellow-legged gulls.

     

Basking habitat use and response of freshwater turtles to human presence in an urban canal of Central New Jersey

Pressures of rapid development continue to increase, and recreational activities are becoming a prominent driving force in many urban wildlife communities. Freshwater turtles live in many urban environments, yet little attention has been given to the impact of human recreation upon these communities. We examined the response of basking turtles to observer presence along the towpath of a recreational canal in central New Jersey. All species, except for turtles of the family Kinosternidae, were more frequently observed basking on substrate with less than 50 % canopy cover, log substrate was most preferred, and turtles on the towpath side basked an average of 3 m from the towpath. Turtles were vigilant and over 75 % of C. picta, T.S. elegans, and P. rubriventris responded to observer presence by retreating (swimming away). The distance from the towpath turtles were first seen basking by the observer (approach distance) was significantly correlated with the flight-initiation distance (distance of first respond to observer). Nearly 80 % of the variability in flight initiation distance for Kinosternidae was accounted for by the percent canopy cover, percent cloud cover, and height basking above the water. Researchers aiming to quantify and manage human recreational impact on turtles should examine flight-initiation distances. We encourage wildlife managers of urban parks to construct towpaths or recreational areas at a minimum of 7 m from the water’s edge, maintain moderate vegetation in basking areas, and construct additional basking platforms opposite from towpaths or at great distances from human recreational areas.     

Risk of bird predation and defoliating insect abundance are greater in urban forest fragments than street trees

Predation by natural enemies is important for regulating herbivore abundance and herbivory. Theory predicts that complex habitats support more natural enemies, which exert top-down control over arthropods and therefore can reduce herbivory. However, it is unclear if theory developed in other more natural systems similarly apply to predation by vertebrate and invertebrate natural enemies across urban habitats of varying complexity. We used plasticine caterpillar models to assess risk of predation by birds and insects, collected leaf-feeding arthropods, and measured herbivory in willow oak trees (Quercus phellos) in two seasons to determine how predation influenced herbivory across urban forest fragments, street trees planted near forest fragments, and downtown street trees. Predation attempts by birds and abundance of chewing folivores were greater on trees growing in urban forest fragments than downtown street trees. Bird predation attempts and herbivory levels were inconsistent for near-forest trees. Predation attempts by arthropods did not statistically vary among the three urban tree habitats. Contrary to expectations based on theory, chewing folivore abundance and herbivory were generally highest on trees growing in urban forests, the most complex habitat we studied, and the habitat where risk of bird predation was greatest. We suggest that urban forest fragments provide better habitat than other urban landscapes for both urban birds and chewing folivores by having greater habitat complexity. Therefore, basal resources, such as availability of suitable habitat, mediate top-down effects on herbivores in cities.

     

Vegetation of the urban habitats in the Nile Delta region,Egypt

The present study aims at identifying the plant communities of the urban habitats in the Nile Delta region, Egypt. Four hundred and five stands were selected to represent the variation in eight major types of habitat recognized in the study area. Twenty-five vegetation groups were recognized after application of TWINSPAN. Their ordination using DECORANA indicates moisture, pH, fertility and texture gradients; the hygronitrophilous communities (the moist and fertile stands) inhabit the wet refuse areas (Echinochloa stagnina-Eichhornia crassipes group), mesonitrophilous communities inhabit the dry refuse areas, motor roads and railways (Pluchea dioscoridis, Cynodon dactylon, Panicum repens and Phragmites australis groups), mesic-dry subnitrophilous communities occur on sandy soils (Hordeum murinum, Alhagi graecorum and Desmostachia bipinnata groups) and the dry thermophilous communities of new anthropogenic habitats with coarser texture of sandy and infertile soil along the railways and motor roads at the borders of the Nile Delta (Zygophyllum album and Cornulaca monacantha groups). These results suggest that urban vegetation in the Nile Delta region is favored where disturbance, nutrient and water resources are more abundant.     

Everyday territories: homelessness,outreach work and city space

This article develops a situational approach to understanding urban public life and, in particular, the production of urban territories. Our aim is to examine the ways in which city space might be understood as comprising multiple, shifting, mobile and rhythmed territories. We argue that such territories are best understood through attending to their everyday production and negotiation, rather than handling territory as an a priori construct. We develop this argument from the particular case of the street‐level politics of homelessness and street care. The experience of street homelessness and the provision of care in the public spaces of the city is characterised by precarious territorial claims made and lost. We describe some of the ways in which care work with rough sleepers is itself precarious; ‘homeless’, in lacking a distinct setting in which it might get done. Indeed, outreach work takes place within and affirms homeless territories. The affirmation of territory is shown to be central to the relationship developed between the workers and their rough sleeping clients. We also show, however, the ways in which outreach workers operate on territory not their own, twice over. Outreach work is precarious in that it is practised within, and can run counter to, other territorial productions in which the experience of urban need and the work and politics of care are entangled. In sum, this article aims to move beyond static and binary understandings by developing a mobile and situational approach to city space which recognises the intensive yet overlooked work of territorial production.     

Legacy effect of trees in the heritage landscape of a peri-urban golf course

Negative environmental impacts of golf courses have received more attention than positive ecological contributions. We studied the mature tree communities and their legacy effect in a historical urban-fringe golf-course site in Hong Kong covering 170-ha with well-managed natural-cum-cultural landscape. Some 44.3 % of the site is covered mainly by large trees forming a mature peri-urban forest. The 94 species in 35 families offer a high species diversity exceeding local secondary and climax fengshui woodlands with notable rare and protected species. Tree species composition, richness and legacy effects brought by anthropogenic and natural factors were investigated by three habitats with varying naturalness and three golf courses with different age. Landscape zone is remarkably heterogeneous versus other microhabitats (fairway and woodland) and the heterogeneity of tree communities amongst the three courses is relatively weak. Synergistic operation of natural regeneration (natural legacy effect) and anthropogenic management (anthropogenic legacy effect) has fostered diversity accumulation. On the one hand, temporal changes in landscape fashion through a century and variations in site management have driven and maintained species diversity. On the other hand, the founder effect of inherited and cultivated species, as well as successful invasion and establishment of native species, have imposed floristic imprint and inertia on woodland habitat. The findings suggested that urban golf courses can serve as potential hotspots for biodiversity conservation within urban ecosystems.     

Home range and habitat use of feral cats in an urban mosaic in Pietermaritzburg,KwaZulu-Natal,South Africa

Feral cats (Felis catus) are one of the world’s worst invasive species with continuing expanding populations, particularly in urban areas. Effects of anthropogenic changing land-use, especially urbanisation, can alter distribution and behaviour of feral cats. Additionally, resource availability can influence home range and habitat use. Therefore, we investigated home range and habitat use of feral cats (n?=?11) in an urban mosaic with varying degrees of urbanisation and green spaces in Pietermaritzburg, KwaZulu-Natal, South Africa. Using global positioning cellular trackers, individual feral cats were followed for a minimum of six months. Minimum convex polygons (MCP) and kernel density estimates (KDE) were used to determine their home range, core area size, and habitat use. Mean home range (± SE) for feral cats was relatively small (95% MCP 6.2?±?4.52 ha) with no significant difference between male and female home ranges, nor core areas. There was individual variation in home ranges despite supplemental feeding in the urban mosaic. Generally supplemental resources were the primary driver of feral cat home ranges where these feeding sites were within the core areas of individuals. However, the ecological consequences of feeding feral cats can increase their survival, and reduce their home ranges and movement as found in other studies.     

Black widow spiders in an urban desert: Population variation in an arthropod pest across metropolitan Phoenix, AZ

The effects of urban disturbance are critical to understand, as the majority of the world??s population now resides in urban centers. For example, urbanization often leads to reduced species diversity at the expense of a few urban-adapted taxa. However, it remains unclear why some taxa thrive following human disturbance whereas others do poorly. The western black widow spider, Latrodectus hesperus, thrives in disturbed, urban habitat??often forming dense aggregations (i.e., infestations) relative to typical low-density, desert populations. We examined the population dynamics of ten black widow aggregations spread across metropolitan Phoenix, AZ, during the peak of the breeding season (June?CAugust). Here we show that prey abundance, female mass, web volume and population density exhibit minimal temporal variation across the breeding season, but that prey abundance, female mass and population density show significant spatial variation across the ten urban aggregations. Our measure of prey abundance and foraging success, the number of prey carcasses found in black widow webs, shared a strong positive relationship with female mass and population density, but not with web volume. Surprisingly, female mass, web volume and population density were not correlated with each other. The abiotic variables we measured at each site did a poor job of explaining black widow population parameters, although we did find a marginal trend for more recent developments to harbor denser black widow aggregations. Our findings support the generalization that urbanization heightens spatial variation, and we suggest that local urban prey abundance is influential in promoting urban infestations full of heavy, fecund female black widows. Studies of the population ecology of urban pests are necessary to identify the mechanisms allowing some species to thrive following human disturbance while much native biodiversity is lost following urbanization.     

Habitat use in basking Northern water (Nerodia sipedon) and Eastern garter (Thamnophis sirtalis) snakes in urban New Jersey

The habitat use of basking northern water (Nerodia sipedon) and Eastern garter (Thamnophis sirtalis) snakes was examined along the Raritan Canal, an urbanized area of central New Jersey. There were significant differences between the two species with respect to cloud cover, canopy cover, and the distance to the path and the water, but not with respect to percent of the body exposed to the sun, and percent of the snake that was visible. Water snakes were more likely to bask on bushes, branches and logs than were garter snakes. Garter snakes basked when both the air and water temperature were lower than did water snakes. The lack of basking sites in the water suggests that those along shore are important, including the low hanging branches used by the watersnakes.     

Seasonal activity patterns of sympatric eastern gray squirrels (Sciurus carolinensis) and fox squirrels (Sciurus niger) in a Midwestern metropolitan region

Niche partitioning reduces interspecific competition, facilitating coexistence. In urban ecosystems, however, habitat loss reduces species’ ability to spatially partition activity. Temporal partitioning may thus increase in urban areas as species, unable to avoid each other spatially, partition time to avoid competition. In Midwestern US cities, eastern gray squirrels (Sciurus carolinensis) and fox squirrels (S. niger) co-occur and compete for resources. We identified urban gray and fox squirrel activity patterns and how they vary with season, land cover, and among sites where they do and do not co-occur using camera-trap data. Both species’ activity patterns varied with season and canopy and impervious surface cover. Gray squirrel activity patterns varied in the presence of fox squirrels only in the fall, providing limited support for our temporal partitioning hypothesis. Temporal niche partitioning may thus play a role in supporting these species co-existence when competition is seasonally-elevated (e.g., fall hording), but appears less important in other seasons.

     

Hadeda Ibis (<Emphasis Type="Italic">Bostrychia hagedash</Emphasis>) urban nesting and roosting sites

Hadeda Ibis (Bostrychia hagedash) have increased in population size and expanded in range in South Africa possibly as a result of increased use of exotic trees for nesting and roosting in urban areas. We investigated the urban nesting and roosting sites of the Hadeda Ibis by measuring tree height and species used by Hadeda Ibis for nesting and roosting in Pietermaritzburg, KwaZulu-Natal, South Africa. We expected Hadeda Ibis nests and roosts to have habitats, like wetlands, to be within 10 km of the roost or nest tree. Hadeda Ibis nest and roost locations were mapped using ArcGIS and available resources (grasslands, wetlands, plantations, other natural water sources) 10 km around each roost and nest tree were determined. Results showed that Hadeda Ibis use exotic trees for nesting and roosting in urban areas more than indigenous trees. This may be because exotic trees are more available in urban environments, particularly those trees that have ornamental value. Hadeda Ibis did not nest and roost closer to expected resources. Although previously associated with wetlands, Hadeda Ibis in urban environments were not close to natural water sources. This can be explained by swimming pools providing accessible drinking water and well watered lawns providing suitable foraging habitat therefore allowing them to roost and nest in this urban habitat.