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1.
Living in the city: can anyone become an ‘urban exploiter'?   总被引:2,自引:0,他引:2  
Aim As urban landscapes expand, shifts in biodiversity are occurring. This is leading biogeographers and ecologists to consider human‐dominated landscapes in their current work. One question that arises is: what characterizes those species that are widespread in the most highly urban environments compared with those restricted to less urbanized areas in the city? Here, we aim to identify the traits that enable species to become urban exploiters, i.e. to dominate highly urbanized surroundings. Identifying these traits may help us better predict and possibly mitigate the biotic homogenization occurring in these areas. Location Israel in general, with special focus on the city of Jerusalem. Methods Combining literature and field‐based data for birds in Israel we compared phenotypic, behavioural and life‐history traits between urban exploiters and urban adapters. The latter occur in urban landscapes, but are characteristic of the less urbanized parts of the city. We then examined the trends along a finer field‐sampled gradient of increasing urbanization from sub‐natural to downtown areas within the city of Jerusalem. Results Urban exploiters and adapters differed primarily in social structure and migratory status: exploiters were significantly more social and sedentary than urban adapters. Clear trends were also seen for dietary preferences along a gradient of increasing urbanization in Jerusalem, such that, with increasing urbanization, the proportion of granivorous species increased whereas the proportion of species feeding on invertebrates declined. In contrast, neither relative brain size nor behavioural flexibility, as measured by feeding innovations, differed significantly among urban exploiters and adapters in Israel or along the urbanization gradient in Jerusalem specifically. Main conclusions The results of our study suggest that being successful in more vs. less urbanized environments in the city is not necessarily a factor of brain size nor of how flexible and behaviourally innovative the species is; rather, it depends on a combination of traits, including diet, degree of sociality, sedentariness and preferred nesting sites.  相似文献   

2.
Cities can be regionalized in intra-urban and peri-urban areas. The space between urban areas and adjacent systems represents an ecological transition that often acts as a semi-permeable biological filter. In this study, we assessed changes in avian community species richness, density, and composition at different peri-urban ecotones (i.e., urban-croplands, urban-grasslands, urban-shrublands) of northeastern Mexico City. Species richness was lower in the urban component of urban-grassland and urban-shrubland ecotones, while bird densities were higher in the urban components of the urban-grassland and urban-shrubland peri-urban ecotones, mainly due to the high number of urban exploiter species. However, the urban-cropland peri-urban ecotone exhibited a different pattern, with similar low bird species richness and density values between both components (urban and non-urban). A species composition analysis revealed that urban bird communities were not influenced by adjacent non-urban habitats, since the urban components of peri-urban ecotones were more similar among them than in relation to the rest of non-urban components. In summary, results of this study show that urbanization can represent an important biological filter for birds, often reducing species richness and homogenizing avian communities at local scales. As the environmental variables determining ecological processes related to the semi-permeable filter effect that urban areas pose to biodiversity might depend on urban habitats, regions, and spatial scales, further studies are needed to fully understand this phenomenon.  相似文献   

3.
Urbanization is currently considered one of the most rapid types of global environmental change. More and more wildlife species are subject to increasing anthropogenic disturbance, but only some of them adapt to become successful urban exploiters. Although a number of fixed life history characteristics may enhance population persistence in an urbanized landscape, behavioural traits are thought to be critical for colonization of a novel urban environment. Within the class of birds, behavioural responses to urban environment have been assessed mostly for passerine species. Here, I examined behavioural alterations in a recently founded urban population of a reed‐nesting rallid species, the Eurasian coot Fulica atra. I found that urban coots adapted to nest in anthropogenically transformed littoral zones with scarce or no emergent vegetation, which precluded efficient nest concealment. Despite this, urban individuals spent, on average, less time incubating due to more frequent bouts off the nest than suburban conspecifics. This pattern was likely possible due to the relaxation of predation pressure in the colonized urban environment. Urban birds were also more aggressive, approached a human intruder at the nest more closely and were more likely to actively defend their nests. Finally, they had a reduced level of physiological stress (as measured with heterophil/lymphocyte ratio) when compared with suburban individuals. In conclusion, the behaviour of coots from the recently founded urban population was consistent with behavioural syndromes found in typical urban exploiters. The results support the central role of behavioural adaptation in successful colonization of novel environments by wildlife.  相似文献   

4.
Urban development has a marked effect on the ecological and behavioural traits of many living organisms, including birds. In this paper, we analysed differences in the numbers of wintering birds between rural and urban areas in Poland. We also analysed species richness and abundance in relation to longitude, latitude, human population size, and landscape structure. All these parameters were analysed using modern statistical techniques incorporating species detectability. We counted birds in 156 squares (0.25 km2 each) in December 2012 and again in January 2013 in locations in and around 26 urban areas across Poland (in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence of twelve potential environmental variables on species abundance and richness was assessed with Generalized Linear Mixed Models, Principal Components and Detrended Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded in this study. On average (±SE) 13.3 ± 0.3 species and 288 ± 14 individuals were recorded in each square in each survey. A formal comparison of rural and urban areas revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural areas. There was almost a complete separation of rural and urban bird communities. Significantly more birds and more bird species were recorded in January compared to December. We conclude that differences between rural and urban areas in terms of winter conditions and the availability of resources are reflected in different bird communities in the two environments.  相似文献   

5.
Linking foraging decisions to residential yard bird composition   总被引:1,自引:0,他引:1  
SB Lerman  PS Warren  H Gan  E Shochat 《PloS one》2012,7(8):e43497
Urban bird communities have higher densities but lower diversity compared with wildlands. However, recent studies show that residential urban yards with native plantings have higher native bird diversity compared with yards with exotic vegetation. Here we tested whether landscape designs also affect bird foraging behavior. We estimated foraging decisions by measuring the giving-up densities (GUD; amount of food resources remaining when the final forager quits foraging on an artificial food patch, i.e seed trays) in residential yards in Phoenix, AZ, USA. We assessed how two yard designs (mesic: lush, exotic vegetation; xeric: drought-tolerant and native vegetation) differed in foraging costs. Further, we developed a statistical model to calculate GUDs for every species visiting the seed tray. Birds foraging in mesic yards depleted seed trays to a lower level (i.e. had lower GUDs) compared to birds foraging in xeric yards. After accounting for bird densities, the lower GUDs in mesic yards appeared largely driven by invasive and synanthropic species. Furthermore, behavioral responses of individual species were affected by yard design. Species visiting trays in both yard designs had lower GUDs in mesic yards. Differences in resource abundance (i.e., alternative resources more abundant and of higher quality in xeric yards) contributed to our results, while predation costs associated with foraging did not. By enhancing the GUD, a common method for assessing the costs associated with foraging, our statistical model provided insights into how individual species and bird densities influenced the GUD. These differences we found in foraging behavior were indicative of differences in habitat quality, and thus our study lends additional support for native landscapes to help reverse the loss of urban bird diversity.  相似文献   

6.
Ecological theory suggests that the coexistence of species is promoted by the partitioning of available resources, as in dietary niche partitioning where predators partition prey. Yet, the mechanisms underlying dietary niche partitioning are not always clear. We used fecal DNA metabarcoding to investigate the diets of seven nocturnal insectivorous bird and bat species. Low diet overlap (2%–22%) supported resource partitioning among all species. Differences in diet corresponded with species identity, prey detection method, and foraging behavior of predators. Insects with ultrasonic hearing capabilities were consumed significantly more often by birds than bats, consistent with an evolved avoidance of echolocating strategies. In turn, bats consumed a greater proportion of noneared insects such as spruce budworms. Overall, our results suggest that evolutionary interactions among bats and moths translate to dietary niche partitioning and coexistence among bats and nocturnal birds.  相似文献   

7.
Urbanization is one of the most extensive and ecologically significant changes happening to terrestrial environments, as it strongly affects the distribution of biodiversity. It is well established that native species richness is reduced in urban and suburban areas, but the species traits that predict tolerance to urbanization are yet little understood. In birds, one of the most studied groups in this respect, evidence is appearing that acoustic traits influence urban living, but it remains unknown how this compares to the effects of more obvious ecological traits that facilitate urban living. Therefore, it remains unclear whether acoustic communication is an important predictor of urban tolerance among species. Here, with a comparative study across 140 European and North American passerines, I show that high song frequency, which is less masked by the low‐frequency anthropogenic noise, is associated with urban tolerance, with an effect size over half that of the most important ecological trait studied: off‐ground nesting. Other nesting and foraging traits accepted to facilitate urban living did not differ for species occurring in urban environments. Thus, the contribution of acoustic traits for passerine urban tolerance approximates that of more obvious ecological traits. Nonetheless, effect sizes of the biological predictors of urban tolerance were low and the phylogenetic signal for urban tolerance was null, both of which suggest that factors other than phenotypic traits have major effects on urban tolerance. A simple possibility is exposure to urbanization, as there was a higher proportion of urban‐tolerant species in Europe, which is more urbanized than North America.  相似文献   

8.
In Australian urban environments, revegetation and vegetation restoration are increasingly utilized conservation actions. Simple methods that help assess the utility of urban vegetation for bird species will help direct this effort for bird conservation purposes. We therefore examine whether ecological principles can be used to predict, a priori, the relative abundance of different bird species in urban vegetation. Our model proposes that a bird species will be in greater abundance where vegetation structure better reflects its foraging height requirements, and this relationship will be moderated by the landscape context of the patch. To quantify and test this model, we created an index to rank existing and revegetated urban vegetation sites in order of greatest expected abundance for each of 30 bird species. We tested this model, alongside two simpler models which consider landscape context and foraging height preferences alone, using bird abundance data from 20 woodland remnants and 20 revegetated sites in Brisbane, Australia. From these bird abundance data, we calculated the relative abundance of each species between the top‐ranking sites and lowest‐ranking sites. The model which incorporated both foraging height requirements and landscape context made predictions that were positively correlated with the data for 77% of species in remnant vegetation and 67% in revegetation. The results varied across species groups; for example, we achieved lower predictive success for canopy foraging species in the less mature revegetation sites. Overall, this model provided a reasonable level of predictive accuracy despite the diversity of factors which can influence species occurrence in urban landscapes. The model is generic and, subject to further testing, can be used to examine the effect of manipulating vegetation structure and landscape context on the abundance of different bird species in urban vegetation. This could provide a cost‐effective tool for directing urban restoration and revegetation efforts.  相似文献   

9.
I studied the effects of a nonseasonal environment with a high diversity of plant species in a community of white-bellied spider monkeys (Ateles belzebuth belzebuth) in the Yasuní National Park, Ecuador. During 10 2-wk follows of focal individuals across 1 yr, I collected 1268 h of observation data on ranging and foraging. The environment had strong effects on both the foraging and ranging behavior of the monkeys. Yasuní spider monkeys are similar to spider monkeys in more seasonal environments in that ripe-fruit consumption dominates the diet. However, Yasuní spider monkeys exhibit an extremely diverse diet that parallels the variety of foods available to them, consuming more than 238 species of fruits. The impressive dietary variety increased even more with increased observation time, as I had not previously observed in the spider monkeys’ diet 40% of the fruit species the subjects consumed during the final follow. Ripe fruits remain the most important item in the diet year-round, supplemented with decayed wood or leaf flush. Local rarity of plant species means that fruiting patches are an average of 420 m apart, and mean patch residence times are short, only 8.1 min. Visits to an average of 11.5 feeding patches/d lead to a mean daily path length of 3311 m, longer than reported for any other Ateles species, and long compared to most other primate species. The long daily paths of Yasuní spider monkeys reflect travel costs resulting from foraging in a hyperdiverse nonseasonal environment.  相似文献   

10.
《农业工程》2022,42(4):255-258
The Oriental Pied Hornbill is one of the ten species of hornbills found in Malaysia, and known to be an adaptable species with regard to utilising available food resources, although there is not much information about its foraging behaviour where its habitat overlap with human activities. We observed an opportunistic behaviour of a pair of Oriental Pied Hornbills preying on farmed edible bird nest swiftlets, in the state of Sabah, Malaysia as captured by closed circuit television utilised by an edible bird nest entrepreneur. A more detailed study could better assist and determine the frequency of this particular predation-prey interaction which may be a new cause of human-wildlife conflict in Malaysia and illuminating the diet diversity and adaptive ability of this hornbill species to seeking their dietary range.  相似文献   

11.
Urban bird communities exhibit high population densities and low species diversity, yet mechanisms behind these patterns remain largely untested. We present results from experimental studies of behavioral mechanisms underlying these patterns and provide a test of foraging theory applied to urban bird communities. We measured foraging decisions at artificial food patches to assess how urban habitats differ from wildlands in predation risk, missed-opportunity cost, competition, and metabolic cost. By manipulating seed trays, we compared leftover seed (giving-up density) in urban and desert habitats in Arizona. Deserts exhibited higher predation risk than urban habitats. Only desert birds quit patches earlier when increasing the missed-opportunity cost. House finches and house sparrows coexist by trading off travel cost against foraging efficiency. In exclusion experiments, urban doves were more efficient foragers than passerines. Providing water decreased digestive costs only in the desert. At the population level, reduced predation and higher resource abundance drive the increased densities in cities. At the community level, the decline in diversity may involve exclusion of native species by highly efficient urban specialists. Competitive interactions play significant roles in structuring urban bird communities. Our results indicate the importance and potential of mechanistic approaches for future urban bird community studies.  相似文献   

12.
Despite the recognised conservation value of phylogenetic diversity, little is known about how it is affected by the urbanisation process. Combining a complete avian phylogeny with surveys along urbanisation gradients from five continents, we show that highly urbanised environments supported on average 450 million fewer years of evolutionary history than the surrounding natural environments. This loss was primarily caused by species loss and could have been higher had not been partially compensated by the addition of urban exploiters and some exotic species. Highly urbanised environments also supported fewer evolutionary distinctive species, implying a disproportionate loss of evolutionary history. Compared with highly urbanised environments, changes in phylogenetic richness and evolutionary distinctiveness were less substantial in moderately urbanised environments. Protecting pristine environments is therefore essential for maintaining phylogenetic diversity, but moderate levels of urbanisation still preserve much of the original diversity.  相似文献   

13.
We analyzed the variation in island bird communities of urban environments related to habitat characteristics, using regression/classification tree analyses. Data from field censuses in cities/towns representing the urban heterogeneity of the whole island were obtained in Tenerife (Canary Islands, Spain). Urban bird abundance in Tenerife was negatively affected by altitude and the cover of dry Euphorbia shrubs and positively influenced by the height and cover of the tree layer. Species richness was negatively associated with building cover and positively related to tree height and altitude. Data from field censuses in Tenerife were compared with that of similar urban environments in the mainland (Madrid Province, central Spain). Species diversity was higher in the urban sample of Tenerife than in that of Madrid and the proportion of bird species from the regional pool captured by urban environments was higher in the island than in the mainland. Nine native species and three alien species were more abundant in island urban environments than in the continent (densities, at least, 100% higher), the converse occurring for only five species. At a biogeographic scale, we conclude that the avifauna of Tenerife Island is more prone to occupy a new artificial environment than the mainland bird fauna of central Spain.  相似文献   

14.
Mangrove bird communities in north Australia comprise relatively few passerine species compared with other arboreal habitats in the region. Mangroves are dominated by a few tree species and there are potentially few resource axes available for partitioning by terrestrial birds. Competition for limited resources is predicted to cause strong niche differentiation and a highly structured, but low diversity, bird assemblage. Using multivariate and bipartite network analyses based on 1771 foraging observations (33% of 5320 behavioral observations), we examined resource partitioning by 20 terrestrial bird species in mangroves of north Australia. The mangrove bird community largely comprised generalist insectivores that partitioned insects by size with moderate‐to‐high interspecific overlap in diet. Gleaning for insects was the most common foraging mode. Few species specialized on nectar. Flowers of one or more mangrove species were available in every month of the year and insect abundance was correlated with flowering peaks. Niche differentiation by birds was determined by food type and foraging mode more than by broad spatial (mangrove zones) or temporal (seasonal) segregation of the use of resources. There was little evidence of bird species saturation or species sorting, suggesting loose species packing and a lesser role than expected for species interactions and interference competition in structuring the bird assemblage in mangroves.  相似文献   

15.
This study examined the importance of habitat heterogeneity on the avian community composition, and investigated the scale at which species abundances respond to habitat variables. The study was conducted within a diverse landscape matrix of a shaded coffee region in Mexico. To detect at which characteristic spatial scale different species and foraging guilds respond most strongly we analyzed the effect of plot-, patch- and landscape-level variables at different spatial extent (i.e., different kilometer radii) on species composition and foraging guilds. We used redundancy analysis to identify species–environment correlations, and to identify predictor variables that best explained the bird community structure, quantified the influence of plot-, patch- and landscape-level variables on the bird community composition. In addition, we used the 4th-corner method to detect significant relationships between the dietary guilds and plot-, patch- and landscape-level variables. We recorded 12,335 individuals of 181 bird species; 105 bird species were recorded foraging within the shaded coffee plantations. We found that plot- and landscape-level variables significantly explained the bird community composition best across all scales, and were significantly correlated with the abundance of the dietary guilds. In contrast, patch-level variables were less important. Habitat composition variables (i.e., coffee, forest and agricultural area) were among the most important predictors. Canopy structure was more important than other vegetation structure variables in explaining dietary guild structure. Hence, the maintenance of a heterogeneous landscape with a high-quality matrix within an agro-ecological region enhances bird conservation.  相似文献   

16.
If deterministic processes consistently structure ecological communities, similar patterns in species interactions should be observed in different geographic areas that experience similar environmental conditions. I tested for convergent patterns in dietary diversity of fruit-eating birds inhabiting similar latitude forests in the Northern and Southern hemispheres. I observed birds foraging for fruits over two fruiting seasons in both Nelson Lakes National Park, South Island, New Zealand, and the Pacific Rim National Park, Vancouver Island, Canada. I then conducted rarefaction analyses to compare community-level and species-level dietary diversity between geographic locales. Relationships between the size of each bird species and the average size of fruits consumed were also assessed. Results showed that the New Zealand bird community had greater overall dietary diversity than the Canadian community. However, similar levels of dietary diversity were observed among species within communities in both hemispheres. Positive relationships between bird size and fruit size were observed in New Zealand, but not in Canada. Therefore, while results showed some support for dietary convergence between hemispheres, several substantial differences were also observed, leading to mixed support for convergent patterns in the diets of fruit-eating birds between hemispheres.  相似文献   

17.
We compared the vegetation structure between old (>70 year) stands of planted diversified native forests and stands of Eucalyptus tereticornis embedded in a mosaic of Eucalyptus stands. We then tested for differences in the abundance, species richness, species composition, and ecological traits (forest dependence, sensitivity to forest fragmentation, and diet) of the understory bird assemblages inhabiting both kinds of stands. We expected differences in the structure of the bird assemblages because of the different origins and management strategies (contrary to native stands, Eucalyptus stands were selectively logged in the past). Three stands of each habitat (native and Eucalyptus) were sampled with mist nets during 11 months. Eucalyptus stands had a denser understory, whereas native plantations had a more developed vertical structure and a greater density of native trees. The abundance distribution of bird species was more homogeneous in Eucalyptus than in native stands. Eucalyptus had slightly higher species richness (36 species) than native stands (32 species). The composition of species and the occurrence of the diet, forest dependence, and sensitivity to forest fragmentation categories were similar between habitats. Some bird species (e.g. Turdus leucomelas), however, were more abundant in one habitat over the other. Old stands of Eucalyptus and planted native forest can harbor a diverse bird community similar in structure but not exactly equivalent for individual bird species. Planting native diversified forests and keeping set‐aside stands of the exotic tree should be viewed as complementary rather than alternative strategies for maintaining bird diversity within plantations.  相似文献   

18.
Anuran–prey selection might be mediated by traits, either by mismatches in predator and prey traits (preventing interactions) or by predator selection of prey traits (encouraging interactions). These effect traits could be summarized in two contrasting foraging strategies: “active” and “sit-and-wait” foragers. We evaluated whether anurans could be classified into groups of species sharing traits associated with their diet, and what is the relation between particular effect traits of anurans and their prey. We collected anurans and identified their stomach contents once during dry, minor, and major rain seasons in six dry forest sites in the Colombian Caribbean. For each of the 19 anuran species and 436 prey items, we registered six effect traits. We applied RLQ and fourth-corner methodologies to relate predator and prey traits through their interaction matrix. Predators were assigned to five groups according to their differences in locomotion, body shape, proportion of the jaw width, mode of tongue protrusion, and strata preferred. Regarding preys, species were assigned to four groups according to their gregariousness, body shape and hardness, defensive traits, and mobility. Body size of both, predators and prey, had a minor contribution in the group assignment. We found that predators using active search target low-mobility preys, whereas species using sit-and-wait strategy target highly nutritive prey that are difficult to manipulate. By linking amphibian diet with foraging strategies, we hope to contribute to the understanding of mechanisms behind anuran–prey food web patterns and to build more realistic models of functional response to changing environments.  相似文献   

19.
Foraging behavior, one of the adaptive strategies of clonal plants, has stimulated a tremendous amount of research. However, it is a matter of debate whether there is any general pattern in the foraging traits (functional traits related to foraging behavior) of clonal plants in response to diverse environments. We collected data from 97 published papers concerning the relationships between foraging traits (e.g., spacer length, specific spacer length, branch intensity and branch angle) of clonal plants and essential resources (e.g., light, nutrients and water) for plant growth and reproduction. We incorporated the phylogenetic information of 85 plant species to examine the universality of foraging hypotheses using phylogenetic meta-analysis. The trends toward forming longer spacers and fewer branches in shaded environments were detected in clonal plants, but no evidence for a relation between foraging traits and nutrient availability was detected, except that there was a positive correlation between branch intensity and nutrient availability in stoloniferous plants. The response of the foraging traits of clonal plants to water availability was also not obvious. Additionally, our results indicated that the foraging traits of stoloniferous plants were more sensitive to resource availability than those of rhizomatous plants. In consideration of plant phylogeny, these results implied that the foraging traits of clonal plants (notably stoloniferous plants) only responded to light intensity in a general pattern but did not respond to nutrient or water availability. In conclusion, our findings on the effects of the environment on the foraging traits of clonal plants avoided the confounding effects of phylogeny because we incorporated phylogeny into the meta-analysis.  相似文献   

20.
Understanding the effect of landscape configuration on the bird species richness and their functional traits (dietary preferences) is important to link the conservation and restoration plans to the production of the crops. Our aims were: 1) to study the influence of forest types (native, mixed and plantations) on the bird species richness in two agroforestry landscapes (heterogeneous/homogeneous); 2) to assess the effect of size/density of forest patches in the birds’ functional traits; 3) to evaluate the effect of isolated trees on them, and 4) to discuss conservation and restoration measures for the birds’ functional traits in agroforestry landscapes. We used hierarchical occupancy models to evaluate the effect of different landscape metrics and detectability measures on bird communities. We recorded a total of 64 bird species. The estimated species richness was considerable higher in homogeneous landscape (31.7 ± 2.7) than heterogeneous (27.3 ± 2.5). Our results showed the bird assemblage had a positive trend with native forests, negative with mixed forests and neutral trend for plantations. The granivores and insectivore’s species showed significant preferences for homogeneous landscape, while omnivores had significant preferences for heterogeneous landscape. Carnivores/Piscivores and herbivores/frugivores species did not show preferences by any landscape type. The response of functional traits depended on different forests attributes. The isolated trees had a significant effect on the birds’ functional traits. In conclusion, it is necessary a deep knowledge about the relationship between the landscape configuration and the bird species richness/functional traits. These findings could help in the future with the conservation, restoration, and rewilding policies in this important hotspot of biodiversity, avoiding alterations in the ecosystem services.  相似文献   

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