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1.
Considerable attention has been devoted to the effects of people on birds and mammals, usually in wilderness or semiwilderness, but relatively little has been directed at reptiles in heavily populated areas. This paper examines the role of investigators and pedestrians on Northern water (Nerodia sipedon) and Eastern garter (Thamnophis sirtalis) snakes basking along a canal in New Jersey. The protocol involved 1–3 investigators approaching snakes that were basking between a path and the Raritan Canal. Investigators walked along the path until they were perpendicular to the snake, observed them for 60 seconds, and then approached them directly. Nearly 40% of the variability in distance to first respond for water snakes (N = 135) was accounted for by distance the snake was from the path, number of observers, and number of people currently using the trail, while 27% of the variability in time to respond was accounted for by number of observers, distance to path and water, and air temperature. There was no significant model for garter snakes (N = 33). Nearly 30% of water snakes, but only 5% of garter snakes, responded during the approach of an observer, and another 32% of water and 45% of garter snakes responded within the first minute of stopping on the trail nearest to them. Water snakes responded when the observer was farther away from them than did garter snakes. As the number of pedestrians on the path increased, water snakes responded when people were farther from them, but there were no differences for garter snakes in response distance. These data indicate differences in response, with water snakes responding sooner than garter snakes. Few garter snakes responded when they were over 150 cm from the path, while a quarter of the water snakes responded when they were from 200 to 300 cm from the path, suggesting that paths should be at least 400 cm from water, providing safe basking sites for water snakes. Further, the data indicate that walking past snakes without stopping results in less disturbance than stopping to watch them.  相似文献   

2.
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.  相似文献   

3.
The composition of the plant community in remnant patches of open grassy woodlands with an overstorey of Eucalyptus camaldulensis was investigated along an urban–rural gradient in Melbourne, Australia. The plant community showed very little difference between patches along the gradient, particularly in terms of the indigenous plant species. Average annual rainfall was the main factor contributing to patterns of indigenous plant species richness, while the level of urbanization in the surrounding landscape had a strong influence on the number of non-indigenous species recorded in the remnant plant community. Patterns of species richness were largely influenced by landscape-scale factors, while the percent cover of indigenous and non-indigenous plant species were more strongly influenced by patch scale factors. The findings of this study suggest that the plant communities investigated during this study appear to be relatively resilient to changes in the landscape associated with urbanization, but the plant community may be affected by predicted changes in average annual rainfall associated with climate change.  相似文献   

4.
Heterick  B.E.  Casella  J.  Majer  J.D. 《Urban Ecosystems》2000,4(4):277-292
A survey examined the influence of Argentine (Linepithema humile (Mayr)) and coastal brown ant (Pheidole megacephala (Fabricius)) populations on other ants in the Perth metropolitan area, Western Australia. Twelve gardens (yards) were sampled; four infested by Argentine ants, three infested by coastal brown ants, and five controls where these two tramp ants were absent or collected only as isolated strays. Collection methods used were pitfall trapping and hand collection. A total of 27 species was recorded. Eight of these species, including the above two tramp ants, are non-native to the region. Pheidole megacephala was the most abundant species, comprising 95.4% of ants in P. megacephala–infested gardens. Linepithema humile comprised 92.1% of ants in L. humile–infested gardens. Other common ants were the native Iridomyrmex chasei and the introduced species Tetramorium simillimum and Tetramorium bicarinatum. The cryptic introduced species Cardiocondyla nuda and Tetramorium simillimum appear able to persist in small numbers in L. humile–infested gardens, but virtually no other ant species occurred where the coastal brown ant was well established. Mean richness, diversity, and evenness were significantly different between P. megacephala–infested and control gardens, and significantly different between L. humile–infested and control gardens. Diversity and evenness, but not richness, were significantly different between P. megacephala–infested and L. humile–infested gardens. Ordination analysis revealed that the three types of gardens had very different ant community profiles.  相似文献   

5.
Considerable attention has been devoted to the effects of people and their vehicles on birds and mammals, but possible effects on reptiles in populated areas have received less attention. Moreover, the effects of human activities on reptile reproductive success itself has been harder to demonstrate. This paper examines the effect of management of off-road vehicles in New Jersey’s pinelands on the reproductive success of pine snakes (Pituophus melanoleucus) from 1986 to 2005. We used the percentage of snakes in each hibernaculum that were young of the year (hatchlings) as an indicator of reproductive success, and compared this percent for five hibernacula that were in an area with varying degrees of off-road vehicle (ORV) disturbance, with 12 hibernacula in areas with no ORV disturbances (reference sites). This percent took into account differences in absolute numbers from one location to another, and over time due to hibernacula destruction (by people or predators) and natural variations (food supply). The ORV pressure in the pinelands is intense because it lies within the most densely populated urban area in the United States. Although the number of snakes in the reference hibernacula varied over the years from 46 to 63, the percent of young in these hibernacula did not vary significantly over the 20 year period (21–29%). In contrast, the percent-young in the disturbed sites differed significantly in years without ORV disturbance (28%) compared to those with ORV disturbance (15 and 16%, P < 0.01). Further, there were no differences between the percent of young in the reference sites and those in the disturbed site in years without ORV disturbance. ORV disturbance ceased only with the creation of large dirt berms coupled with fences that could not be easily broken. These data indicate the importance of having detailed population data on pine snakes in hibernacula, on ORV use (or indications of such use), and of managing ORV use to protect sensitive populations. Maintenance of healthy pine snake populations in urban areas may require continued adaptive management.  相似文献   

6.
Urban open spaces are highly valued for their contribution to the quality of life in the cities [Tenkel (1963). Cities and space: The future use of urban land. Baltimore:Johns Hopkins Press; Burgess, Harrison and Limb (1998). Urban Studies, 25, 455–473; Madanipour (1999). Environment and Planning B: Planning and Design, 26, 879–891]. Third world cities, for example, Chiang Mai (Thailand), are no exception with regard to the role of urban open space in achieving such a goal [Tantayanusorn (2003). Unpublished doctoral thesis. Melbourne:Royal Melbourne Institute of Technology]. However, the provision of urban open space as a social public facility is coming low in priority in comparison to other market-demanded facilities in the form of roads, car parks, clean water, electricity and the like. Such a fact was corroborated by a study conceived by Thailand's Social Research Institute (1996) which reveals that 73% of Chiang Mai population wanted more public open space.This paper aims at exploring the revitalization of existing traditional open spaces (kuang)—which is usually categorized as ‘religious land’, hence it is a religious property—in Chiang Mai as an intermediate strategy in providing the much needed public open space. In doing so, the physical and cultural characteristics of kuang have to be elaborated, while at the same time the local aspirations on urban open space were canvassed. The combined analysis of those two inquiries resulted in a proposal of kuang wat—a variance of kuang—utilization as an agent of urban open space provision in the project of achieving quality of urban life in Thai city of Chiang Mai.  相似文献   

7.
Although southern flying squirrels (Glaucomys volans) are present in many urban parks, squirrel-habitat relationships in such areas are poorly understood, limiting conservation efforts. Our objective was to quantify the effects of forest structure at multiple scales on flying squirrel distribution in New York City (NYC) parks. From 18 June–24 August 2001, we captured flying squirrels in 5 New York City parks and measured forest structure at the ground, shrub, understory, and overstory levels at trap sites. To examine the importance of forest structure to squirrels, we compared (1) habitat variables between trap stations where squirrels were captured and not captured and (2) habitat variables between parks with and without documented squirrel populations. Our data suggest that areas with forests containing smaller trees at higher densities, dense woody ground cover, and little herbaceous ground vegetation may not provide the food, cavities, ease of movement, or allow predator detection necessary to be used by or support flying squirrel populations. Other factors, such as the size and density of stumps and snags may be important to non-urban squirrel populations, but not populations in NYC parks. Because NYC parks contain almost all of the remaining woodlands within the City, forests within these areas should be a conservation priority.  相似文献   

8.
Singh  Nikisha  Price  Cormac  Downs  Colleen T. 《Urban Ecosystems》2021,24(5):905-914

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.

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9.
An impounded estuarine marsh scheduled for restoration in 2003 and three nearby unimpounded marshes (Spartina alterniflora, S. patens/Iva frutescens, and Phragmites australis) in highly urbanized NY/NJ Harbor were studied to assess the impact of impoundment on marsh structure and function and to identify trajectories of ecosystem change following removal of the levee. Aboveground biomass was greater in the Phragmites and S. alterniflora marshes (706–809 g/m2) as compared to the S. patens/I. frutescens and impounded marshes (378–588 g/m2). Macro-organic matter (0–30 cm) was similar across all marshes (7452–9212 g/m2). The S. patens/Iva frutescens marsh had the lowest aboveground biomass, but contained more plant species (2.8 species/0.25 m2) and greater species diversity (H = 1.33) than the other marshes (1.3–2.0 species/0.25 m2, H = 0.16–0.78). Rates of sediment and nutrient accumulation were lower in the impounded marsh (335 g sediment/m2/yr, 97 g C/m2/yr, 6.5 g N/m2/yr, and 0.9 g P/m2/yr) than in the reference marshes (422–1515 g sediment/m2/yr; 111–160 g C/m2/yr; 7–10 g N/m2/yr; 1.6–2.8 g P/m2/yr). Our results indicate that the impounded marsh does not contain the high species diversity of the high marsh, nor does it provide the same level of functions as naturally inundated marshes. Reintroduction of tidal inundation to the impounded marsh will enhance water quality benefits and favor development of S. alterniflora salt marsh community structure.  相似文献   

10.
Forested riparian buffers are an increasingly common method of mitigating the negative effects of impervious surface cover on water quality and wildlife habitat. We sampled larval southern two-lined salamanders (Eurycea cirrigera) in 43 streams, representing the range of impervious surface cover and forested riparian buffer width across Wake County, NC, USA. Larval abundance decreased with increasing impervious surface cover in the upstream catchment, but was not affected by buffer width. This is likely a result of an incomplete buffer system and culverts or other breaches along streams. Larval abundance increased with detritus cover in the stream to a threshold and then decreased as detritus continued to increase. As percent pebble substrate in the stream increased, especially in perennial streams, larval salamander abundance also increased. We suspect salamanders were unable to migrate with the water column during dry periods in intermittent streams with sedimented interstices below the surface, resulting in low abundances. A combination of increased peak flows and sedimentation, reduced base flow, and chemical changes likely reduces the abundance of salamanders in urban and suburban streams. We suggest creation of catchment-wide, unbreached buffers to maintain the integrity of stream habitats in urbanizing watersheds.  相似文献   

11.
Spatial variation in soil inorganic nitrogen across an arid urban ecosystem   总被引:4,自引:1,他引:3  
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.  相似文献   

12.
Many in situ upgrade projects in developing countries fail. I tell the story of how one in South Africa (Oukasie) succeeded, both in the eyes of residents as well as the wider development community. I noticed that the residents of Oukasie managed to accomplish far more than other similar upgrades within the same timespan. Within just three years, from being ‘illegal’ and on the bucket sewage system, all households had their own water connection and toilet as well as access to a range of community facilities. The leadership of the community were getting job offers from the private-sector, and the former ‘whites-only’ town of Brits was beginning to play an integral part in Oukasie's development. I wanted to understand how this was all possible. My paper addresses this question and shows how, through using politics (e.g. political tactics and links to politicians) and storytelling, the community built a much more successful project than otherwise would have been the case. Throughout this paper I use Oukasie as a ‘model’ to demonstrate that successful in-situ upgrading is both feasible and desirable in the South African context, given the scarcity of government resources relative to the housing backlog. Oukasie, thus, becomes a vehicle for discussing a broader range of issues which are relevant to development projects in general and in situ upgrade projects in particular.  相似文献   

13.
Two species of tree squirrel inhabit the Chicago region, the fox (Sciurus niger) and gray (S. caroliniensis) squirrel. Chicago residents submitted squirrel observations and associated landscape variables via a Website, allowing us to map squirrel distributions. Data were analyzed for patterns of correlation. At a smaller scale, we did a foot survey of fox and gray squirrels in the suburb of Oak Park, replicating an earlier study and comparing results. Gray squirrels were associated with densely populated areas, parks and campuses, fox squirrels with suburban areas. Compared to gray squirrels, fox squirrels were more likely to be observed in areas of high cat density. In the suburb of Oak Park, the current trend seems to be an extension of gray squirrel distribution and a decrease in fox squirrel distribution. Our study provides support for the idea that fox and gray squirrel coexistence is facilitated by a trade-off between managing the cost of predation and foraging efficiency, gray squirrels out-competing fox squirrels in areas of high food and low predator (or pet) density.  相似文献   

14.
Considerable attention has been devoted to the effects of people on birds and mammals, usually in wilderness areas. In contrast, human disturbance of reptiles has largely been ignored. Many reptiles, such as snakes, are hard to conserve because they are difficult to locate and protect. The young are especially vulnerable to predators when they first hatch and must emerge from nest sites. In this paper, the response of pine snake (Pituophis melanoleucus) hatchlings to the presence and handling by people was observed in the laboratory and in the field. Pine snakes lay their eggs in underground burrows in open sandy pine barrens, and the hatchlings push their way to the surface to emerge. Hatchlings that were visually-disturbed or touched as they emerged returned immediately to their tunnels and nests, and required more time to re-emerge than did their siblings that were not visually-disturbed or touched during their initial disturbance. In nature, undisturbed pine snakes showed similar re-emergence times to those from the laboratory, and disturbed snakes required longer to re-emerge. These data suggest that in nature even the presence of people in nesting areas of pine snakes would lengthen the time the young are in burrows, exposing them to additional threats from predators. This suggests that parks or nature reserves with vulnerable snake populations should restrict human disturbance during the period when young snakes are emerging from their nests. Field observations indicate that a set-back distance of more than 12 m from known nesting areas is essential to protect emerging hatchlings.  相似文献   

15.
As urbanization expands into rural areas, an increase in the number of non-native plant species at the urban-rural interface is expected due in large part to the increased availability of propagules from ornamental plantings. A study investigating the distribution of non-native plants in the understories of riparian forests across an urban-to-rural gradient north of Columbus, GA was initiated in 2003. A significantly greater number of non-native plant species occurred at the urban sites and at one site at the urban-rural interface, where 20 to 33% of the species encountered were non-native. In contrast, at the more rural sites non-native species comprised 4–14% of the total number of species. However, the importance values of non-native species as a whole did not change significantly across the land use gradient due to the high frequency and abundance of three non-native species (Ligustrum sinense, Lonicera japonica, and Microstegium vimineum) in the majority of the watersheds. Reductions in species richness and overstory reproduction associated with these non-natives could impact long-term forest structure and ecosystem function.  相似文献   

16.
Urban-associated changes can have immediate or long-term consequences on animal populations. Such changes may be assessed through parasite prevalence and abundance in wildlife hosts, as urbanization can influence parasitism and disease transmission in wildlife. Snakes are widespread and diverse vertebrates that often persist in urban environments; however, parasitism of snakes in urban environments has yet to be studied, leaving the roles of snakes in parasite transmission uncharacterized. Field ecology, microscopy, molecular techniques, and geographic information science (GIS) were integrated to characterize parasitism of snakes in an urban old-growth forest park. The species, sex, mass, length, location, and prevalence of ecto-, hemo-, and fecal parasites were determined for 34 snakes of 6 species. Ectoparasites (mite), hemoparasites (Hepatozoon spp.), and fecal parasites (Entamoeba spp., Trichomonas spp., Strongloides spp., and an unidentified helminth) were detected in snakes and 64.7?% of snakes were infected by at least one of these parasites. Parasite infections were generally not related to the sex, age, or body condition of snakes. The locations of infected snakes were used to produce risk maps indicating where parasite prevalence is predicted to be greatest. The analysis of these maps indicated that snakes with fecal parasites were closer than non-infected snakes to the edge of the forest. This study confirms that snakes may be important parasite hosts or reservoirs in parasite transmission pathways in urban environments and it provides an integrative multidisciplinary approach that may be used to monitor parasitism dynamics in other urban wildlife areas.  相似文献   

17.
Fox squirrels in an urban environment had an average litter size of 2.83 (95% CI 2.5, 3.16) which was similar to rural populations. Nonetheless, the proportion of squirrels reproductively active during the summer/fall breeding season (0.73) and annually (spring + summer/fall) was higher (1.23) than previously recorded for non-manipulated rural populations. The average monthly survival rate () of urban juvenile fox squirrels during the first 14 weeks of life was higher than reported for adult populations in the area. High rates of reproduction and juvenile survival yielded high juvenile to adult ratios (juveniles/adults) averaging 0.44. Retention of juveniles after 6 months (15%) was significantly less (χ 2 = 7.24, p = 0.0071) than adults/subadults (40%). Results suggest that the urban environment provides quality habitat for fox squirrels and fox squirrels in urban environments have the potential to be a source population for surrounding suburban and rural environments.  相似文献   

18.

Human development and disturbances can be determinants of population viability of some vertebrates in human-impacted ecosystems. The effects on the behavior and population dynamics of reptiles are not well-studied in urban environments. This paper examines the importance of pine forest clearings, openings, and paleodunes for nesting pine snakes (Pituophis melanoleucus melanoleucus) in the New Jersey Pinelands, and the risk to nesting females and offspring from off-road vehicles (ORV). In this ms we 1) develop a rating scale for ORV activity that can be modified for evaluating risk to other vertebrates, 2) compare general habitat features of nesting areas used in the early 1980s with those used in 2020, and 3) examine the fate of nesting areas used in the 1980s and the intensity of ORV use in both time periods. In 2020, nests were located at only 2 of the 10 nesting areas used in 1983 (20%), and only one of the 10 was a paleodune. In comparison, in 2020, 9 of 13 new nesting areas were on paleodunes (69%). In 1983, ORV activity on nesting areas ranged from very low to medium. In the intervening years development and ORV activity increased markedly, and snakes abandoned most areas by 2020. ORV activity in those sites still utilized for nesting increased to high and very high. In 2020, ORV activity ranged from very low (7%) to very high (19%) of the 42 nests. With increasing urban development, nesting pine snakes are using mainly paleodunes deep in the forest, and are exposed to high or very high ORV activity (43%), suggesting concern for viable snake populations in the wake of continued human activity and ORV use.

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19.
Research has demonstrated that humans detect threatening stimuli more rapidly than nonthreatening stimuli. Although the literature presumes that biases for threat should be normative, present early in development, evident across multiple forms of threat, and stable across individuals, developmental work in this area is limited. Here, we examine the developmental differences in infants' (4‐ to 24‐month‐olds) attention to social (angry faces) and nonsocial (snakes) threats using a new age‐appropriate dot‐probe task. In Experiment 1, infants' first fixations were more often to snakes than to frogs, and they were faster to fixate probes that appeared in place of snakes vs. frogs. There were no significant age differences, suggesting that a perceptual bias for snakes is present early in life and stable across infancy. In Experiment 2, infants fixated probes more quickly after viewing any trials that contained an angry face compared to trials that contained a happy face. Further, there were age‐related changes in infants' responses to face stimuli, with a general increase in looking time to faces before the probe and an increase in latency to fixate the probe after seeing angry faces. Together, this work suggests that different developmental mechanisms may be responsible for attentional biases for social vs. nonsocial threats.  相似文献   

20.
Influence of seasonality and vegetation type on suburban microclimates   总被引:2,自引:0,他引:2  
Urbanization is responsible for some of the fastest rates of land-use change around the world, with important consequences for local, regional, and global climate. Vegetation, which represents a significant proportion of many urban and suburban landscapes, can modify climate by altering local exchanges of heat, water vapor, and CO2. To determine how distinct urban forest communities vary in their microclimate effects over time, we measured stand-level leaf area index, soil temperature, infrared surface temperature, and soil water content over a complete growing season at 29 sites representing the five most common vegetation types in a suburban neighborhood of Minneapolis–Saint Paul, Minnesota. We found that seasonal patterns of soil and surface temperatures were controlled more by differences in stand-level leaf area index and tree cover than by plant functional type. Across the growing season, sites with high leaf area index had soil temperatures that were 7°C lower and surface temperatures that were 6°C lower than sites with low leaf area index. Site differences in mid-season soil temperature and turfgrass ground cover were best explained by leaf area index, whereas differences in mid-season surface temperature were best explained by percent tree cover. The significant cooling effects of urban tree canopies on soil temperature imply that seasonal changes in leaf area index may also modulate CO2 efflux from urban soils, a highly temperature-dependent process, and that this should be considered in calculations of total CO2 efflux for urban carbon budgets. Field-based estimates of percent tree cover were found to better predict mid-season leaf area index than satellite-derived estimates and consequently offer an approach to scale up urban biophysical properties.  相似文献   

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