Butterfly diversity,habitat and vegetation usage in Hong Kong urban parks

The conservation value of urban parks for butterfly communities remains poorly understood, particularly for tropical butterflies in Asia. We conducted point count and route transect butterfly surveys, and used them to sample four habitats located within 13 urban parks across Hong Kong. We found 1054 individuals and 58 species of butterflies recorded in 60 survey hours over 6 months. This represents approximately one quarter of the entire known Hong Kong butterfly species list. Over 30 % of the individuals counted were Catospilia sp. but six of the species identified are classified locally as rare or very rare. Tree-covered habitats and grasslands showed higher butterfly diversity than open areas. The most common butterfly behavior was “directed flight,” which we also found to be habitat-dependent and most common in ponds and open areas. We additionally observed the use of vegetation in urban parks, which included 40 species of nectar plant and four records of butterfly oviposition. The high butterfly diversity, presence of rare species and usage of vegetation (especially as a nectar resource) we documented in this study suggests that urban parks have some conservation value for Hong Kong. However, the use of pesticides and heavy vegetation clearing may limit significant butterfly reproduction and population growth. Altogether these results emphasize the diversity of uses of urban parks for butterflies in Hong Kong while also providing possible directions for improvement in habitat and vegetation management that could increase urban park value for biodiversity.     

Determining the effect of urbanization on generalist butterfly species diversity in butterfly gardens

This study investigates the effects of urbanization on local butterfly populations and the role of butterfly gardens in preserving regional butterfly diversity. Data are from 135 butterfly gardens of varying size, location, and number of blooming plants in the Washington DC metropolitan area observed during 2001 and 2002. We investigated the species diversity for comparable gardens in rural, suburban, and urban locations to determine whether the landscape matrix surrounding otherwise suitable habitat affects the diversity found in the habitat. We hypothesized that, once factors such as garden size and number of blooming plant species were taken into account, butterfly diversity for 12 generalist species would decrease as urbanization increased. We found that there were systematic decreases (with one exception) in diversity from rural to suburban to urban gardens only for medium-sized gardens (0.10 to 0.20 ha) with one to ten types of blooming plants, and large gardens (>0.20 ha) with over 20 types of blooming plants. Gardens of other sizes or plant communities showed some decreases in diversity from rural to suburban to urban sites, but these differences were not consistent across the urban/rural gradient. Results of this study indicate that local butterfly diversity is negatively affected by increasing levels of human population, but that the matrix is just one factor determining generalist species diversity.     

The effects of landscape scale on greenery and traffic relationships with urban birds and butterflies

Actions and policies to enhance biodiversity in the urban landscape must match the spatial scale at which biodiversity responds to the management and target variables. To this end, we compare the importance and effect of different kinds of greenery cover and road-lane density on bird and butterfly species richness between two landscape scales: 50-m versus 126-m radii around point counts (equivalent to areas of 0.8 h and 5 ha, respectively). We also compared the results against those of an earlier study using 500-m walking transects with widths of 100 m (i.e., 5 ha). Road lane density was more important at the 126-m than 50-m radius for both birds and butterflies. For birds, natural vegetation or forest cover and cultivated shrub cover were also more important at 126-m radius whereas the cultivated tree canopy cover was more important at 50-m radius. Cultivated tree cover and natural vegetation or forest cover were positively associated with species richness while road lane density and cultivated shrub cover were negatively associated with species richness. The results from point counts generally corroborate the results from the transects-based study, except that the short-duration point counts performed poorly in sampling butterflies. Our results indicate that in designing urban greenery policy, the plot sizes of individual developments is an appropriate spatial scale for the stipulation of tree cover targets, while urban planners have more flexibility to allocate natural greenery at broader spatial scales.

     

Urban gradients alter the diversity,specific composition and guild distribution in tropical butterfly communities

The increasing expansion of the urban environment has been considered one of the causes of biodiversity loss. Due to the decrease of the quantity and quality of habitats, this process causes the restriction of organisms to sometimes-specific microhabitats. The patterns of variation of the biodiversity along the environmental gradients, however, are still poorly understood. This study evaluated how urban gradients affect the diversity, specific composition and frequency of guild of the community of butterflies. Butterflies were collected in three transects continuously traversing the urban, rural and preserved habitats using baited traps and by active sampling. We found that the urban gradient acts as an environmental filter in the butterfly communities, reducing the richness and frequency of guilds of frugivorous butterflies, structuring the community through turnover, but without effects in the abundance. This study shows the importance of the urban gradients approach in the butterfly community and its applicability in the management of urban areas in order to include native vegetation along the gradients, aiming at increasing environmental heterogeneity, to preserve butterflies and maintain the ecosystem services and network interactions in altered landscapes.

     

The impact of urbanisation on avian species: The inextricable link between people and birds

This study investigates the impact of urbanisation on birdlife in a major city. Line transects and point counts were used to survey birds in three habitat types: parkland, residential areas and business/industrial areas. Abundance, richness and diversity of assemblages were determined for all bird species and for those birds native to the area. Behaviours of birds, and of human residents in relation to birds, in these urban areas were documented, including all instances of avian aggression. Bird species, including a subset of native bird species, have greater abundance and richness in parklands. Overall species diversity is greatest in residential habitat types, but native diversity is greatest in parklands. Introduced species are most abundant in business/industrial habitat types. The most frequent aggressive encounters were initiated by noisy miners Manorina melanocephalas, one of the four most common species throughout all habitat types (other common species include the rainbow lorikeet Trichoglossus haematodus, rock dove Columba livia and common myna Sturnus tristis). Other behaviours involved birds utilising food and roost resources and were classified as being caused by active and passive human behaviours. These outcomes indicate that local changes to the environment can impact the bird species by providing different food and roost resources. Human residents and local governments have a range of tools to modify the diversity of urban areas. Further research is needed to determine alternative definitions of modification, such as defining it as open space, and investigating the health of the avian populations in urban areas.     

Managing urban wetlands for multiple use: research,restoration, and recreation

Conservation of urban wetland habitat is challenging, because multiple uses must coexist. We use examples from California and Wisconsin to describe potential synergies among recreation, restoration and research activities (the 3 R's). Allowing passive recreation is often essential to garner public support for habitat protection, restoration, and research. In turn, restoration activities can improve the appearance of degraded sites, and designing the work as a research experiment can serve the scientific community. Two projects at Tijuana Estuary support the 3 R's. (1) Oneonta Tidal Linkage is a 0.7-ha tidal channel and salt marsh that was excavated from disturbed upland to bring wetland habitat closer to the Visitor Center (thereby reducing visitor intrusion into natural marsh habitat, where endangered species would be disturbed). It supports an ambitious field experiment that is testing the importance of species diversity in restoration; it also includes a bridge that serves the interpretive program, and it adds 0.7 ha of wetland habitat that helps restore regional biodiversity. (2) A larger excavation (8 ha) of former tidal wetland will soon add wetland habitat, while testing the importance of tidal creek networks in ecosystem functioning and offering views and interpretive opportunities. A third situation, at the 485-ha University of Wisconsin–Madison Arboretum, concerns restored wet prairies, which provide habitat for native species and serve many hikers. Urban stormwater flows into and degrades the Henry Greene Prairie, allowing aggressive plants to invade. Research and restoration efforts are planned to sustain the habitat and recreation functions. These three models suggest that recreation, restoration, and research are compatible uses of urban wetland habitats.     

Urban parks: refuges for tropical butterflies in Southeast Asia?

Rapid economic development has accelerated urbanisation and biodiversity loss in Southeast Asia. Studies of urban ecology have suggested urban parks can be effective refuges for wildlife in temperate regions, but their effectiveness as refuges in rapidly urbanising tropical regions is understudied. We examined the species diversity of butterflies in urban parks in the Federal Territory of Kuala Lumpur and investigated the relationships between butterfly species richness and three park variables: i) park size, ii) distance from the central business district and iii) park age. Standardised butterfly sampling was conducted across different microhabitat types at each park: i) groves, ii) hedges, iii) flowerbeds and iv) unmanaged areas. We recorded 572 butterflies belonging to 60 species (97 % considered common) from five families. Although species richness was positively correlated with park size and age and negatively correlated with distance from the central business district; the correlations were weak and not statistically significant. However, species richness of host-specialist species was significantly positively correlated with park size and age. The highest species richness (65 % of observed species) was recorded in the unmanaged microhabitat. It is likely that both park planting scheme and the presence of early successional plants in unmanaged microhabitat led to highest butterfly species richness in parks that contained all four microhabitat types. Whether a diverse planting scheme and increased size and number of unmanaged areas in urban parks can improve the ability of parks to sustain populations of rare butterflies in the face of future urbanisation remains to be seen.     

Butterflies in the city: a review of urban diurnal Lepidoptera

Human migration to urban centers has resulted in diverse environmental disturbances that affect biodiversity. Although urbanization has been highlighted as one of the main drivers of biodiversity endangerment, this topic is still poorly studied in many countries. In order to establish the status quo of the ecology of butterflies in urban centers, we gathered publications focused on urban butterflies (Lepidoptera). We compiled a total of 173 studies from 37 countries and more than 110 urban areas, including published papers and theses (1956–2015). Most papers (69 %) addressed ecological topics, 14 % were focused on biological conservation, and 17 % corresponded to species lists. In summary, most studies revealed a negative impact of urbanization intensity on butterfly diversity (richness and abundance). In fact, we found studies reporting local extinctions due to urbanization, highlighting the causes related to them. The study of charismatic urban wildlife groups, such as butterflies, is a promising field, as there are still important gaps in our comprehension of the ecological patterns and processes that occur in urban areas. Undoubtedly, understanding the response of butterflies to urbanization will aid in the development of urban biodiversity management, planning, and conservation strategies worldwide, which together with knowledge of other wildlife groups and socioeconomic variables, will lead us to more sustainable, livable, and biodiverse cities.     

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.

     

Bird and butterfly communities associated with two types of urban riparian areas

We examined the distribution of birds and butterflies at two types of urban riparian areas in the metropolitan area of Denver, Colorado, USA. The sites consisted of relatively natural areas containing native woody vegetation, and those that had been highly modified with trees and shrubs removed and planted with lawn grass. Species richness of both butterflies and birds differed significantly between the two types of sites. Species richness, however, was not significantly correlated between birds and butterflies. Bird abundance was similar between site types but consisted of two assemblages. Brewer's blackbirds, common grackles, bank swallows, and mourning doves were abundant at wooded sites while American robins, European starlings, house sparrows, house finches, and mallards were more abundant at lawned riparian sites. Butterfly abundance was less at lawned sites. This contrast in bird and butterfly response to habitats suggests they respond to different habitats in distinct ways. Both taxon groups, however, were important discriminators between habitat types. Overall, butterfly and bird species richness was 44% less at highly modified riparian sites.     

Nested patterns in urban butterfly species assemblages: respective roles of plot management,park layout and landscape features

Increasing numbers of cities are currently developing sustainable policies aimed at promoting urban biodiversity and ecological dynamics through the planning of green networks and the implementation of more sustainable management practices. These human activities can strongly influence environmental factors on which the organization of ecological communities at different scales depends. Thus, it is of fundamental importance to understand the relative impact of local management, green space design and landscape features on the distribution and the abundance of species in urban areas. On the basis of 2 years of butterfly surveys in urban public parks within an extensive Mediterranean metropolitan area, Marseille (South-East France), the aim of this paper is to provide a better understanding of the effect of these three environmental scales (plot, park, landscape) on the composition and organization of species assemblages. Using variation partitioning and nestedness analysis on ecological data aggregated at plot-level and park-level respectively, we demonstrate the preponderant effect of landscape scale features on urban butterfly assemblages. Our results also highlight an important co-variation of plot management, park layout and urban landscape features, in their interaction with the community structure of urban butterflies. Although there is no significant species-area relationship, significantly nested patterns arise in species composition. Selective colonization appears as a driving force constraining the constitution of species assemblages within the city. However, a prospective study on adjacent more natural areas suggests that biotic limitations, interspecific competition and habitat filtering may play an important role if a larger portion of the urbanization gradient is explored, which remains to be investigated.     

Diversity,abundance, and species composition of ants in urban green spaces

Urbanization threatens biodiversity, yet the number and scope of studies on urban arthropod biodiversity are relatively limited. We sampled ant communities in three urban habitats (forest remnants, community gardens, vacant lots) in Detroit and Toledo, USA, to compare species richness, abundance, and species composition. We measured 24 site characteristics to examine relationships between richness and composition and habitat patch size, vegetation, and urban features. Ant richness was higher in forests (26) than in gardens (14) and intermediate in vacant lots (20). Ant richness in gardens and vacant lots negatively correlated with abundance of an exotic ant species (Tetramorium caespitum); thus this ant may affect native ant richness in urban habitats. Ant composition differed with habitat type, and abundance was lowest in forests. Site characteristics varied with habitat type: forests were larger, had more woody plants, higher woody plant richness, more branches, and leaf litter whereas lots and gardens had more concrete and buildings. Vacant lots had taller herbaceous vegetation, and gardens had higher forb richness, density, and more bare ground. Differences in vegetation did not correlate with ant richness, but several vegetation factors (e.g. patch size, number and size of trees, leaf litter, and amount of concrete and buildings) correlated with differences in ant species composition. Additional factors relating to soil, nests, or microclimatic factors may also be important for urban ant communities. Implications for biodiversity conservation in urban ecosystems are discussed.     

Determinates of inner city butterfly and bee species richness

Although urbanization is increasing worldwide, relatively few studies have investigated patterns of urban biodiversity outside of city parks and reserves, in urban neighborhoods where people live and work. We evaluated models including local and landscape factors that might influence the bee and butterfly richness of community gardens located within densely populated neighborhoods of the Bronx and East Harlem in New York City (>10,000 people/km²). The gardens were surrounded by buildings and limited amounts of green space (3,600–17,400 building units and 10–32% green space within a 500 m radius). Contrary to our initial prediction that landscape green space might be especially influential in this heavily urbanized setting, the most highly supported models for both bee and butterfly richness (based on Akaike Information Criterion) included just the local, within-garden variables of garden floral area and sunlight availability. There was marginal support for models of bee richness including the number of building units surrounding gardens within a 500 m radius (which exhibited a negative association with bee richness). In addition, perhaps because bees are central place foragers that may nest within or near gardens, supported models of bee species richness also included total garden area, canopy cover, and the presence of wild/unmanaged area in the garden. Generally, our findings indicate that sunlight and floral abundance are the major factors limiting local pollinator diversity in this setting. This suggests that rooftop and other “open” urban habitats might be managed to increase local pollinator diversity, even if seemingly “isolated” within heavily developed neighborhoods.     

Urban areas as hot-spots for introduced and shelters for native isopod species

Isopod assemblages were studied in Budapest, capital of Hungary. The analyses of literary and field data revealed a high species richness (28 species), compared to the total species number (57) in Hungary. Habitats characteristics for the city were categorized as native forests, urban forests, gardens of Buda, gardens of Pest, public parks, densely built-up areas and botanical gardens. We hypothesized that isolated and diverse habitat patches in the city matrix of Budapest support the introduction and establishment of exotic species and the survival of native ones. The composition of assemblages varied among sampling sites, but were characteristic for the biotope categories. We concluded that forests, parks and gardens play an important role in the survival of native isopod populations. Species numbers were highest in the gardens of Buda and in the botanical gardens (both 17 species). The overall presence of cosmopolitan and disturbance-tolerant species indicates an ongoing homogenization process.     

Plant species distribution and spatial habitat heterogeneity in the landscape of urbanizing desert ecosystems in Egypt

Information on the urban flora and vegetation in the industrial new cities in Egypt are insufficient and far from complete. For this reason, this study was undertaken as the first attempt to fill this gap of knowledge. For two successive years (2004 and 2005), a reconnaissance survey was conducted in four new industrial cities: 6th October, El-Sadat, Burg El-Arab and 10th Ramadan; aiming at: (1) recognizing the floristic composition and vegetation structure of each of the studied cities; (2) identifying the main urban habitats dominating the studied cities; (3) comparing the vegetation of the urban habitats at the boundaries of each city, where desert soil merges gradually with the agricultural land, with that at its centre (purely agricultural land); and (4) analyzing, quantitatively, the vegetation groups (plant communities) that characterize the urban habitats. A total of 189 permanent stands in the four cities were selected to represent the apparent variation in the different habitats. These stands were distributed as follows: 49 in 6th October, 37 in El-Sadat, 45 in Burg El-Arab, and 58 in 10th Ramadan. Altogether, 305 species of the vascular plants constituted the main synanthropic flora and the total number of species varied from 171 in Burg El-Arab, 157 in 10th Ramadan, 144 in Sadat and 132 to 6th October. The largest families that formed the main bulk of the recorded flora were Gramineae, Compositae, Leguminosae, followed by Euphorbiaceae, Chenopodiaceae, Cruciferae, Cyperaceae, Umbelliferae and Solanaceae. Five main urban habitats (from inner city toward outskirts) were distinguished: lawns, home gardens, public gardens, waste lands and desert outskirts. The most species-rich habitat was the waste lands (172 species), while the total number of species varied from 104 in the lawns and 113 home gardens, to 123 in the desert and 133 in the public gardens. Generally, the recorded synanthropic flora within the five main urban habitats can be classified into: (1) cultivated plant species that included ornamentals, hedges, shade plants, fodder plants, vegetables and fruits; (2) canal banks, salinized areas and wetland plants; (3) xerophytic plants of the outskirting desert; and (4) weeds of arable lands. Application of multivariate analyses techniques to 4 floristic data matrices yielded 22 TWINSPAN vegetation groups in the cities, and 26 in the five habitats, clearly separated along the first two axes of DCA.     

How to improve urban greenspace for woodland birds: site and local-scale determinants of bird species richness

Wooded habitats represent hotspots of urban biodiversity, however, urban development imposes pressure on biota in these refuges. Identification of the most influential habitat attributes and the role of local urban characteristics is crucial for proper decisions on management practices supporting biodiversity. We aimed to identify well manageable fine-scale habitat attributes to suggest specific, feasible and affordable management recommendations for green space in cities. We analysed species richness of woodland-associated bird communities and incidence of individual species at 290 sites in a wide variety of green areas scattered across the city of Prague, Czech Republic. Generalized linear mixed models (GLMM) and regression tree analyses were used to identify site-scale (100 m radius sampling sites) and local-scale (200 m and 500 m radius plots) habitat attributes shaping the bird communities at individual sites. Logistic regression was used to assess the responses of individual species to habitat characteristics. Our results imply that at the site scale, management practices should focus on maintenance and promoting species-diverse and older tree stands, with a mixture of coniferous and deciduous trees. Water-bodies and accompanying riparian habitats should be maintained and carefully managed to preserve high-quality remnants of natural vegetation. Presence of a few old trees (about 12 % of tree cover with DBH?>?50 cm) or small urban standing water and watercourses enrich the bird community by at least two species. Species richness of woodland avifauna at particular sites is further supported by the total amount of tree cover in the surroundings, including scattered greenery of public spaces and private gardens. We conclude that proper management at site scale has the potential to increase biodiversity of the urban environment.     

Local and landscape drivers of arthropod abundance,richness, and trophic composition in urban habitats

Urban green spaces, such as forest fragments, vacant lots, and community gardens, are increasingly highlighted as biodiversity refuges and are of growing interest to conservation. At the same time, the burgeoning urban garden movement partially seeks to ameliorate problems of food security. Arthropods link these two issues (conservation and food security) given their abundance, diversity, and role as providers of ecosystem services like pollination and pest control. Many previous studies of urban arthropods focused on a single taxon (e.g. order or family), and examined either local habitat drivers or effects of landscape characteristics. In contrast, we examined both local and landscape drivers of community patterns, and examined differences in abundance, richness, and trophic structure of arthropod communities in urban forest fragments, vacant lots, and community gardens. We sampled ground-foraging arthropods, collected data on 24 local habitat features (e.g., vegetation, ground cover, concrete), and examined land-cover types within 2 km of 12 study sites in Toledo, Ohio. We found that abundance and richness of urban arthropods differed by habitat type and that richness of ants and spiders, in particular, varied among lots, gardens, and forests. Several local and landscape factors correlated with changes in abundance, richness, and trophic composition of arthropods, and different factors were important for specific arthropod groups. Overwhelmingly, local factors were the predominant (80 % of interactions) driver of arthropods in this urban environment. These results indicate that park managers and gardeners alike may be able to manage forests and gardens to promote biodiversity of desired organisms and potentially improve ecosystem services within the urban landscape.     

Tales of urban conservation: <Emphasis Type="Italic">Eumaeus</Emphasis> butterflies and their threatened cycad hostplants

Urbanization has caused the local extinction of several butterfly species around the world, while others have managed to thrive in urban areas. Butterflies of the genus Eumaeus are among the most striking and colorful lycaenid butterflies in the Americas, but their neurotoxic hostplants, cycads, are a highly threatened plant group. The main threats for cycads are the loss and modification of their habitats and their removal for ornamental purposes, which in addition to their slow growth rate, make them highly vulnerable. Ornamental cycads are taken from natural habitats to urban areas, where they are playing an important role for Eumaeus reproduction. We here report two cases in which two Eumaeus species (E. childrenae, E. atala) are following and utilizing ornamental cycads to reproduce in urban areas, showing how significant urban areas can be, ecologically speaking. Aside from having enormous potential as flagship species for conservation in urban areas, these butterfly and plant species, and their interactions, shed encouraging light on the idea of putting reconciliation ecology ideas into action.     

Patterns of pollinator turnover and increasing diversity associated with urban habitats

The role of urban expansion on bee diversity is poorly understood, but it may play an important role in restructuring pollinator diversity observed in rural regions at the urban perimeter. We studied bee communities in two habitats essential for pollinators (residential gardens and semi-natural areas) at 42 sites situated at the edge of greater Montreal, Canada. Bee species richness, abundance and functional diversity all increased with urbanization in both habitat types, but gardens and semi-natural areas supported distinct bee communities with unique responses to urbanization in terms of species turnover. Compared to semi-natural sites, residential gardens supported bees that foraged from a greater number but a lower proportion of available plant species. Bees did not discriminate between exotic and indigenous plant species in either gardens or semi-natural sites and were attracted to flowers in either habitat irrespective of their origins. Protecting semi-natural ruderal areas and providing residential garden habitats for pollinators are both effective means of promoting regional bee diversity in urbanizing regions.     

Vegetation on and around large-scale buildings positively influences native tropical bird abundance and bird species richness

High population growth in the tropics is driving urbanisation, removing diverse natural ecosystems. This is causing native species to suffer while introduced synanthropes flourish. City planners are developing urban greenspace networks, in part trying to address this issue. Architects contribute to these greenspace networks by designing elevated and ground level green spaces on large-scale buildings. However, little evidence is available on whether building green spaces support native fauna. This is true for birds in tropical Singapore that support important ecosystem services and have existence value. Therefore, in this study, we conducted bird surveys and statistical analyses to determine, if and how vegetation on three building green space types (ground gardens, roof gardens and green walls) have a positive impact on native or introduced bird species. We found that elevated greenery (roof gardens and green walls) on large-scale buildings supported a higher richness of birds and abundance of urban native birds than control roofs and walls without vegetation. Ground gardens supported similar levels of native species as roof gardens but also a larger proportion of generalist synanthropes. However, we found no tropical forest habitat specialists across any space type. Therefore, we recommend roof gardens and ground gardens as a potential space for urban natives outside of a less competitive ground-level urban environment. Our study also found certain building design elements (height of elevated space, presence of specific plants) supported different species groups. Therefore, we suggest that these ecological requirements for different species groups are considered when designing a building’s green space.