Are invasive House Sparrows a nuisance for native avifauna when scarce?

Biological invasions are the second most important cause of species extinction. Aided by processes such as transportation and urbanization, exotic species can establish and spread to new locations, causing changes in the function and structure of ecosystems. The House Sparrow is a widespread and highly abundant landbird associated to human presence. Previous studies performed in urban landscapes have suggested that this species could be acting, in synergy with urbanization, as a potential threat to native urban avian assemblages. In this study we assessed the relationship between House Sparrow density and native bird species richness in a region where the sparrows are scarce and sparsely distributed. We surveyed bird assemblages in and around four small-sized human settlements, considering three conditions in relation to House Sparrow presence: urban invaded, urban non-invaded, and non-urban non-invaded. To assess the potential detrimental role of House Sparrows on native bird species richness, we measured, additionally to sparrow densities, 20 predictor variables that describe vegetation structure and complexity, as well as urban infrastructure and human activities across four seasons of 1 year. Our results show that maximum shrub height was positively related to bird species richness, built cover was negatively associated with it, and House Sparrow invaded sites were related to a significant decrease of bird species richness, with increasing richness loss when more sparrows were present. Thus, we here provide evidence that urban areas can act in synergy with the presence of House Sparrows (even in low densities) in the urban-related species richness decline pattern.

     

Sparrows in urban complexity: macro and micro-scale habitat use of sympatric sparrows in Guwahati City,India

In recent decades the House Sparrow and Tree Sparrow have suffered considerable declines. To date, little is known about the fine scale habitat selection of sparrows where they occur together. We investigated how sympatric sparrows used macro and microhabitats in the urban environment of Guwahati city. Survey of sparrows was carried out in 572 locations of different urban settings to find out the city scale distribution. We classified urban habitats and collected micro-habitat variables at 45 point count stations during 2013–2015. Urbanization gradient was found to be influential in limiting the abundance of sparrows. House Sparrow was more common within the urbanized areas compared to low settlement densities located far from the urban core. In contrast, Tree Sparrows were more scattered and seldom found in crowded areas. Spatial overlap was comparatively high in the residential areas adjacent to hillocks. At micro scale, House Sparrow had quadratic response to the degree of urbanization. Both the species avoided areas where urbanization reached the peak; specifically, the areas which were completely devoid of natural vegetation and top soil was paved, and in shopping centers with glass facades. Habitat requirements of both the species at local landscape scale seemed to be similar, although, with some overlaps, they occupied different gradients of the urban environment. Since urban landscapes are highly managed, the fundamental tool for enhancing urban sparrow populations would be the protection of mosaic habitat prioritizing suitable design and management of private gardens and allotments.

     

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.     

Depleted suburban house sparrow <Emphasis Type="Italic">Passer domesticus</Emphasis> population not limited by food availability

Little is known about the environmental factors that limit the demography and abundance of wild vertebrates in highly modified urban environments. The House Sparrow Passer domesticus is a globally widespread species whose urban populations have recently undergone substantial declines particularly in Europe. The environmental drivers of these declines remain unknown. In a previous study we showed that invertebrate availability during the breeding season limited reproductive success but not population size in a suburban sparrow population. In this study we test experimentally whether year-round food availability limits demography and population size. Supplementary feeding involved the provision of invertebrate prey (during the breeding season) plus unlimited high-energy seed (year-round) at 33 sparrow colonies spread across suburban London over two successive calendar years. Thirty-three unfed colonies served as controls. Supplementary feeding increased fledgling abundance, but had no impact on overwinter survival or population size. We conclude that this depleted suburban sparrow population is not limited by food availability, and conservation efforts based primarily on food provision are unlikely to succeed. We also tested whether cross-colony variation in sparrow abundance was correlated with a set of potential environmental stressors including measures of predator abundance and pollution. Sparrows were more abundant, or showed more positive temporal changes in abundance, at localities containing large areas of seed-rich habitat and low levels of nitrogen dioxide air pollution. Further research is merited into the potential impacts of air pollution on the fitness of urban birds.     

Resource use overlap between urban carnivores: Implications for endangered San Joaquin kit foxes (<Emphasis Type="Italic">Vulpes macrotis mutica</Emphasis>)

An urban population of Endangered San Joaquin kit foxes (Vulpes macrotis mutica) has persisted in the city of Bakersfield, (Kern County, California), for several decades. Urban kit foxes may play an important role in future range wide recovery efforts for the species. As such, a comprehensive understanding of the issues that can influence the long-term survival of this population is essential for the development of effective management strategies. Although urban kit foxes have been studied extensively in Bakersfield, interactions between kit foxes and other urban carnivore species are poorly understood. Urban environments can provide a number of opportunities for species to interact in ways not usually observed in natural habitats. Interactions between urban populations of striped skunks (Mephitis mephitis) and kit foxes were investigated at denning locations and cat feeding stations on the California State University-Bakersfield campus, California, USA. A total of 130 individual denning sites were identified, of which 39 (30%) were used by both species. Simultaneous den use by foxes and skunks was recorded on four occasions. Inter and intra-specific aggression was recorded at cat feeding stations on ten separate occasions including three incidences of aggression towards kit foxes by skunks and feral cats (Felis catus). Telemetry data and cat feeding station observations clearly show that interspecific contact does occur in urban environments.     

Invasive <Emphasis Type="Italic">Wisteria</Emphasis> in the Southeastern United States: genetic diversity,hybridization and the role of urban centers

The increasing numbers and negative impacts of invasive species have prompted research on the relationship between human activities and the success of invasive horticultural plants. In this study, we use population genetic relationships to model the escape of a common garden vine, exotic Wisteria, into natural habitats. Urban and naturalized Wisteria populations in Charleston, South Carolina and Tallahassee, Florida were investigated using a combination of chloroplast, mitochondrial and nuclear DNA markers. Fifty-nine of 72 (81.9%) Wisteria collections were hybrids of Wisteria sinensis and W. floribunda. Chi-square analysis of the distribution of shared W. floribunda haplotypes among naturalized and urban populations supports the relationship of time with invasion success. Naturalized populations were more similar to those in historic neighborhoods. The most common haplotype, F1, was encountered 22 times but its distribution was not significantly different between urban and naturalized populations. In contrast, a significantly higher proportion of haplotype F2 found in naturalized populations suggests that selection may also be acting within these populations. Finally, due to extensive human dispersal, there is no relationship between genetic distance and geographical distance among the populations sampled. We conclude that Wisteria’s long history of horticulture, rampant hybridization, and human-aided dispersal are all implicated in the successful ability of these plants to invade natural habitats throughout the USA.     

Bird community responses to different urban conditions in La Paz,Bolivia

Urbanization alters ecosystems worldwide, but little is known about its effects in the Neotropical region. In the present research we examined the relative influence of different levels of urbanization and of some urban development measures on bird species richness, abundance and composition. We surveyed 104 observation stations at which we collected data on the relative abundance of bird species, and also data on seven environmental variables as measures of urban development and human activity. We registered 57 native bird species. Bird species richness and bird abundance increased with lower urbanization levels. Both variables were positively related to vegetation cover and native vegetation, and negatively to built-up cover, abundance of Rock Pigeon (Columa livia), pedestrian rate and car rate. A canonical correspondence analysis produced a significant model that explained 37% of the total variation in species data. This analysis segregated bird species along two important gradients: urbanization and elevation. The most urbanized areas were dominated by a few synanthropic species tolerant to human disturbance, such as Rufous-Collared Sparrow (Zonotrichia capensis), Eared Dove (Zenaida auriculata) or Chiguanco Thrush (Turdus chiguanco). Areas with lower urbanization levels had more species typically associated with native vegetation, such as Plain-Mantled Tit-Spinetail (Leptasthenura aegitaloides) or D’Orbigny’s Chat-Tyrant (Ochthoeca oenanthoides), among others. Elevation had a significant influence in structuring bird communities, with some species restricted to higher elevations and some to lower elevations. Although changes in elevation had an important influence, urbanization had a stronger effect on structuring bird communities. This study provides valuable information and an important baseline for future studies.     

Habitat type,food resources,noise and light pollution explain the species composition,abundance and stability of a winter bird assemblage in an urban environment

At present, urban areas cover almost 3% of the Earth’s terrestrial area, and this proportion is constantly increasing. Although urbanization leads to a decline in biodiversity, at the same time it creates extensive habitats that are exploited by an assemblage of organisms, including birds. The species composition and density of birds nesting in towns and cities are determined by the types of buildings, the structure and maturity of urban greenery, and habitat diversity. In contrast, the habitat traits shaping the community of birds wintering in urban areas are not known. The aim of this work was to assess the influence of habitat structure, food resources and the urban effects (pollution, noise, artificial light) on an assemblage of birds overwintering in an urban area. It was carried out in 2014 and 2015 in the city of Kraków (southern Poland), on 56 randomly chosen sample plots, in which the composition, density and interseasonal similarity of bird assemblage were assessed with line transect method. A total of 64 bird species (mean = 17.7 ± 4.9 SD species/plot) was recorded. The mean density was 89.6 ind./km ±63.3 SD. The most numerous species were Great Tit Parus major, Magpie Pica pica, Blackbird Turdus merula, Blue Tit Cyanistes caeruleus, Rook Corvus frugilegus, Fieldfare Turdus pilaris and House Sparrow Passer domesticus. Noise adversely affected species numbers and density, but artificial light acted positively on the density of birds and their interseasonal stability. The species richness and density of birds were also determined by the number of food sources available (e.g. bird-feeders). In addition, the greater the proportion of open areas, the fewer species were recorded. In contrast, the more urban greenery there was, the greater the density of the entire bird assemblage. Urban infrastructure (buildings, roads, refuse tips) had a positive effect on the interseasonal stabilization of the species composition of wintering birds. The results of this work indicate that the urban effect, i.e. noise and light pollution, apart from purely habitat factors, provide a good explanation for the species richness, density and stability of bird assemblage wintering in urban areas.     

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.

     

Ecological restoration of a fragmented urban shrine forest in southeastern Hyogo Prefecture,Japan: Initial effects of the removal of invasive <Emphasis Type="Italic">Trachycarpus fortunei</Emphasis>

We investigated the species composition of a fragmented forest in Nishinomiya Shrine, southeastern Hyogo Prefecture, Japan. Two escaped ornamental species, Trachycarpus fortunei and Ligustrum lucidum, and bird-dispersed deciduous trees were invading the evergreen broadleaf forest. Invasive and bird-dispersed deciduous species were most abundant along the outer edge of the forest. In 2005, restoration measures were taken to remove all individuals of T. fortunei from the forest. We estimated that, biomass density and leaf area index (LAI, leaf area per unit ground area) of T. fortunei were 0.23 kg m⁻² and 0.77, respectively, which accounted for 8.9% and 27.9% of the biomass density and LAI, respectively, of the entire forest. After removal, canopy openness increased in the understory. However, the understory lacked seedlings and saplings of native species, indicating that active re-vegetation may be needed to accelerate reestablishment of native species in areas that were heavily invaded by T. fortunei. This study represents one of the first examples of active vegetation management in shrine/temple forests in Japan.     

A comparison of Mediterranean Gecko (Hemidactylus turcicus) populations in two temperate zone urban habitats

Urban ecosystems represent unique habitats that might be more or less suitable than natural systems for many species. The Mediterranean Gecko, Hemidactylus turcicus is a synanthropic species that has successfully colonized many urban and suburban areas outside its natural range. In the United States, H. turcicus has been found predominantly in southern states on exterior surfaces of buildings. We compared population density, demographics, and extent of dispersal of populations of H. turcicus at two anthropogenic sites in a temperate region of the United States. The University of Central Oklahoma (UCO) had higher building density and greater cover by anthropogenic surfaces and the Oklahoma City Zoo (ZOO) had lower building density and greater cover by vegetation. Mark and recapture sampling was conducted at UCO from 2006 to 2007 and during 2008 at ZOO. The sizes of the populations at the two sites were estimated using the Schnabel method and population densities were calculated using those estimates. Age class of captured animals, sex of adults, and gravid status of adult females were determined at both sites. We assumed that greater exterior wall surface area of individual buildings at UCO and greater land cover by anthropogenic surfaces might 1) reduce population density and 2) facilitate dispersal there relative to the ZOO. Population sizes and density in animals per ha of land and building cover and demographics were similar at the two sites. Population density per ha of building exterior wall area was higher at ZOO than at UCO. The higher density of animals on buildings, lower proportion of subadults in the population and lower maximum dispersal distance at ZOO suggest that successful diffusion dispersal might be limited at that site relative to UCO.     

The roles of mosquito and bird communities on the prevalence of West Nile virus in urban wetland and residential habitats

This study investigated the impacts of urban wetlands and their adjacent residential environments on the transmission dynamics of West Nile virus (WNV) within the state of New Jersey (USA). A working hypothesis was that urban wetlands decrease the local prevalence of WNV through the dilution effect from increased bird diversity, and through relative reductions in the numbers of competent avian host and mosquito species commonly associated with WNV. Surveys of mosquito and bird communities were undertaken at six urban wetlands and their adjacent residential environments over two seasons (2009, 2010). The community compositions of both avian and mosquito species differed significantly across habitats, and over relatively short geographical distances. Residential areas contained significantly higher proportions of WNV-competent mosquito species (31.25?±?5.3?%; e.g. Culex pipiens and Culex restuans), and WNV-competent avian host species (62.8?±?2.3?%, e.g. House Sparrow and American Robin) when compared to adjacent urban wetlands (13.5?±?2.1?%; 35.4?±?2.1?% respectively). Correspondingly, WNV infection rates within local Culex spp. populations indicate that WNV was more prevalent within residential areas (28.53/1000) compared to wetlands (16.77/1000). Large urban wetlands (>100?ha) produced significantly lower weekly WNV infection rates in local Culex spp. (6.67?±?2.84/1000) compared to small (<15?ha) wetlands (22.57?±?6.23/1000). Avian species richness was also influenced by patch size. Large urban wetlands contained significantly more species than small wetland patches. These results confirm that the community compositions of mosquito and avian hosts are important drivers in WNV infections, and that the ecological conditions that favor transmission are more strongly associated with urban residential environments than with adjacent urban wetlands.     

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.

     

Vegetation composition and structure of woody plant communities along urban interstate corridors in Louisville,KY, U.S.A.

Urban forests adjacent to interstate corridors are understudied ecosystems across cities. Despite their small area, these forests may be strategically located to provide large ecosystem services due to their ability to act as a barrier against air pollutants and noise as well as to provide flood control. The woody vegetation composition and structure of forests adjacent to urban interstates is an important determinant of their ability to provide these services. However, these forest communities may be particularly susceptible to the introduction of exotic invasive species via the interstate and the surrounding city that can potentially alter current and future forest composition. The purpose of this study was to investigate the distribution of native and exotic woody vegetation and tree regeneration in forests along three interstate corridors in Louisville, KY, and to determine potential factors (e.g., traffic density) that are correlated with patterns in the woody vegetation community. We found the most important determinants of vegetation composition along these interstate corridors were the distance from the city center and the presence of an exotic invasive shrub, Amur honeysuckle (Lonicera maackii). Compared with forested plots within 10 km of the city center, plots further from the city center had 81% lower stem density of Amur honeysuckle, 96% higher tree seedling regeneration, and 51% greater woody plant species richness. The primarily native species composition of adult trees in forests alongside urban interstates in Louisville and the regeneration of native tree species provide optimism that these forests can maintain native species while experiencing multiple impacts from the interstate as well as from the surrounding city, emphasizing their important potential for maintaining natural forest functions across the urban landscape.     

Toward increasing avian diversity: urban wildscapes programs

Residential development in urban and suburban settings is a major cause of habitat change affecting avian communities. The effects from land-clearing prior to initiation of construction followed by landscaping focused on traditional aesthetics has reduced habitat diversity at multiple levels. These residential developments generally emphasize the use of ornamental, nonindigenous vegetation with little to no concern for native species and natural vegetation parameters. As a result, avian community composition and diversity is changed. We compared avian communities at three sites in Bexar County, Texas; two residential neighborhoods in the city of San Antonio and an unincorporated undeveloped site, Government Canyon State Natural Area. The residential neighborhoods were a Texas Parks and Wildlife Department certified wildscapes development and a traditionally developed neighborhood. Bird abundance and species richness in the neighborhoods were greater than at Government Canyon State Natural Area (P < 0.01), but no differences existed between the neighborhoods. Bird diversity was greatest at the wildscapes neighborhood (P < 0.01). Further, bird diversity did not differ between the traditional neighborhood and the natural area. Evenness differed among sites (P = 0.006) with the natural area having the greatest value. Bird diversity measures correlated with woody plant density and vertical cover (r = 0.358 to 0.673, P < 0.05) at residential sites. Residential areas incorporating natural landscapes into their design attracted a greater variety of birds than traditionally landscaped residential areas.     

Effects of habitat fragment size and isolation on the density and genetics of urban red-backed salamanders (Plethodon cinereus)

Urban expansion is creating environmental stressors through land use change, habitat fragmentation, and habitat loss. These stressors, along with a host of others, are driving precipitous declines in vertebrate taxa around the world. Amphibians, often requiring a narrow range of environmental conditions, can be especially susceptible to the stressors of environmental change. Despite habitat loss and degradation, some amphibian species continue to persist in altered urban landscapes. The red-backed salamander (Plethodon cinereus) is one such- species and in this study, we assess how habitat patch size affects population density and genetic diversity of salamander populations in and around an urban center in Ohio, United States. Further, we examined patterns of genetic differentiation and landscape connectivity to understand gene flow between populations and tested for historic demographic bottleneck effects. Populations were sampled from 9 urban forest patches ranging in size from less than 1 ha to approximately 250 ha. There was no apparent effect of contiguous habitat patch size on salamander density nor genetic diversity, but we did observe significant genetic differentiation between 97% of pairwise population comparisons. The differentiation observed was not a result of overland distance or effective distance due to landscape resistance. There was evidence of historic bottlenecks at every site. These results suggest that density is driven by within-patch heterogeneity and that genetic diversity is affected by drivers other than patch size or contemporary population density. Our study demonstrates that red-backed salamanders can persist in wooded, urban parks, but that genetic diversity remains susceptible to demographic changes.

     

Ranking profiles of capability sets

In this paper, we present an innovative approach for ranking profiles of capability sets on the basis of equity. An interesting way of capturing the notion of equity is to take into account the extent to which each of the different functioning vectors is shared by the population under consideration (of size n). This is done by defining the ‘common capability sets’ enjoyed by k individuals as the set of functioning vectors simultaneously available to at least k individuals (1 ≤ k ≤ n). These sets are closely related to the original capability sets and have some interesting properties that are examined throughout the paper. We define and axiomatically characterize a capability profile ranking that lexicographically compares the different common capability sets. We would like to thank for helpful discussion and comments to Jorge Alcalde-Unzu, Ritxar Arlegi, Miguel A. Ballester, Jose Enrique Galdón, Antonio Nicolò, Jorge Nieto, Prasanta Pattanaik, John Weymark and the anonymous referees of this paper. The project is supported by Spanish’ Comision Interministerial de Ciencia y Technologia (SEC2003-08105) and by the European Commission (MRTN-CT-2003-504796).     

Shaping Street-Children Organizations Across the Americas

Abstract

Covenant House, a non-governmental, social action organization assisting homeless children in the United States is compared and contrasted with its Latin American counterpart organization, Casa Alianza, which services street-living and street-working children throughout Mexico and Central America. Although Covenant House and Casa Alianza share a common mission: to protect children and guarantee their rights through promoting social justice, clear differences in organizational structure, program philosophy, intervention techniques and client characteristics are evident ltural contexts within which both organizations are embedded reveals how surrounding macrofactors can influence and uniquely shape social action organizations in their efforts to develop and deliver systematic and indigenous responses to the homeless, street-children population throughout the Americas.     

Disordered gamblers with and without ADHD: the role of coping in elevated psychological distress

Attention-deficit/hyperactivity disorder (ADHD) is significantly more prevalent among disordered gamblers than in the general adult population. Despite this, it remains unclear whether co-occurring ADHD is associated with clinically significant differences that call for specialized assessments and treatment planning. The purpose of this article was to explore differences in psychological distress and coping strategies among individuals presenting to an outpatient gambling treatment centre with and without co-occurring adult ADHD. Participants (n = 99) were primarily female (69%) and Caucasian (86%) outpatient treatment-seeking disordered gamblers. At intake, individuals completed self-report measures of coping (Coping Inventory for Stressful Situations – Adult Form), psychological distress (Beck Depression Inventory II) and ADHD (Brown Attention-Deficit Disorder Scales – Adult Form). Results indicated that individuals with ADHD (n = 42) reported significantly more psychological distress and less adaptive coping strategies than those without co-occurring ADHD (n = 57). Mediation analyses showed that an ADHD diagnosis had an indirect effect on psychological distress via the mediator of maladaptive coping. Assessment and treatment should be tailored to address the variety of presentations of gambling disorder. Screening for ADHD at intake may be helpful in creating an individualized treatment plan for disordered gamblers.     

An experimental evaluation of foraging decisions in urban and natural forest populations of <Emphasis Type="Italic">Anolis</Emphasis> lizards

Foraging decisions reflect a trade-off between the benefits of acquiring food and the costs of movement. Changes in the biotic and abiotic environment associated with urbanization can alter this trade-off and modify foraging decisions. We experimentally manipulated foraging opportunities for two Anolis lizard species – the brown anole (A. sagrei) in Florida and the crested anole (A. cristatellus) in Puerto Rico – to assess whether foraging behavior differs between habitats varying in their degree of urbanization. In both urban and natural forest habitats, we measured the latency of perched anoles to feed from an experimental feeding tray. We manipulated perch availability and predator presence, while also taking into account population (e.g., conspecific density) and individual-level factors (e.g., body temperature) to evaluate whether and how these contribute to between-habitat differences in foraging behavior. In both species, urban anoles had longer latencies to feed and lower overall response rates compared to lizards from forests. Urban anoles were also larger (i.e., snout-vent length and mass) in both species and urban A. sagrei were in better body condition than the natural forest population. We postulate that the observed patterns in foraging behavior are driven by differences in perceived predation risk, foraging motivation, or neophobia. Although we are unable to identify the mechanism(s) driving these differences, the substantial differences in urban versus forest anole foraging behavior emphasizes the importance of understanding how urbanization influences animal populations and their persistence in anthropogenically-modified environments.