Area Search Method Research Articles

Inferring intercity freeway truck volume from the perspective of the potential destination city attractiveness

Accurately inferring the spatiotemporal distribution of freeway traffic volume is one of the bottleneck problems for intelligent management of ground transportation. Although the accuracy of the widely used machine learning-based approaches has been improving, these methods on freeway traffic flow inference tend to become more and more complex and unexplainable, and sometimes even contradict the constraints of freeway access. From the perspective of the potential destination city attractiveness, this study proposes a new method to infer freeway truck volume. First, considering the spatial scope and direction constraints of road transportation, a restricted area search method for potential destination cities of freeway traffic trips is proposed. Second, a freeway traffic inference model was constructed by combining distance and the angle-weighted socioeconomic statistics of each potential destination city. Finally, the Shapley additive explanation value was used to explain how the potential destination city attraction affects the freeway traffic flow. The results show that the proposed method only used 10 indicators; however, the prediction results were closer to the true value, and the computational efficiency improved by 3–10 times over the baseline method. The variables related to spatiotemporal heterogeneity were the most significant variable group, followed by the industrial structure of potential destination cities.

Significant records of birds on Puerco Island, Roxas, Palawan, Philippines

We documented a total of 53 species of birds on Puerco Island from May 2016 to December 2019 using a combination of modified area search method and photo-documentation. The number of birds increased from only 15 species in 2014 to 53 in December 2019. Records included two endangered species, 18 migratory and 28 native birds. Monthly monitoring of Barred Rail Hypotaenidia torquata, Olive-backed Sunbird Cinnyris jugularis and Collared Kingfisher Todiramphus chloris showed varying levels of abundance. Nest monitoring of the Nearthreatened Philippine Scrubfowl Megapodius cumingii cumingii, locally called “tabon”, using close circuit television cameras, showed a significant increase from only three nests reported in 2012 to 154 in September 2019. The changes in the species composition and the increase in the breeding population of Philippine Scrubfowl are attributed to the integration of conservation management strategies on Puerco Island.

Past records and current distribution of seabirds at Larsemann Hills and Schirmacher Oasis, east Antarctica

Abstract Seabird populations in Antarctica serve as indicators to assess the impacts of global environmental change. Ecological data on seabirds in Antarctica are scarce due to limited knowledge on their distribution and abundance in most parts of the continent. In this study, we investigated the status of seabird species around the Indian research stations Bharati at Larsemann Hills, Prydz bay and Maitri at Schirmacher Oasis, central Dronning Maud Land located in east Antarctica. We conducted primary surveys during austral summers under the Indian Antarctic Program and compiled published as well as unpublished information on seabird distribution from these areas. We employed intensive area search methods to locate presence of seabird nesting and moulting sites. Ten species were recorded from Larsemann Hills with confirmed breeding of snow petrel, south polar skua and Wilson’s storm-petrel. Only south polar skua and Adélie penguin were reported breeding at Schirmacher Oasis with unconfirmed breeding of Wilson’s storm-petrel. This study presents the first detailed synthesis of status of seabirds from Larsemann Hills and Schirmacher Oasis regions in Antarctica and serves as a strong baseline for future ecological work on seabirds in the sector of operation of Indian Antarctic Program.

Birds Wintering in Heterogeneous Farmland of Poland: Weather-Dependent Temporal Changes in Abundance and Habitat Associations

Bird communities wintering in the mosaic-like farming landscapes of SW Poland were studied to assess drivers of intra-seasonal changes in numbers and habitat associations of birds. During two severe winters (November–March) the complete area search method was applied to count birds and link their occurrence with weather and habitat in six plots (320 ha in total). A modelling approach was used to test birds' responses to environmental factors at community and species levels. These farmlands were inhabited by diverse and dense populations of wintering birds, including a significant proportion of species of conservation concern. Bird numbers revealed decreasing trends, with winter- and species-specific fluctuations, affected in particular by snow cover. The lowest population indices were recorded in mid-winter (February) and remained low until mid-March. Field margins (6.6% of the total area) supported 35.6% of individuals and 55.0% of flocks. The preference for field margins over other farmland habitats was particularly prominent during severe weather conditions. Our results suggest that during severe winters, complex farmlands are important areas for birds, enhancing their known importance to breeding birds. Intense snowfall in mid-winter rather than temperature drops lead to immediate population declines, aggravating the effects of natural food depletion. Adverse weather keeps populations at low levels until mid-March, despite the influx of spring migrants. Behavioural adjustments to winter conditions elicit the characteristic habitat distribution of birds, exposing the crucial importance of non-cropped landscape elements. In particular, the variety of field margins significantly contributes to the persistence of internationally important populations of farmland birds in Poland.

Winter Bird Habitat Use in a Heterogeneous Tallgrass Prairie

In the Flint Hills of Kansas and Oklahoma, U.S.A., grazing land is managed predominantly to promote homogeneous grassland structure. This potentially limits the diversity of habitats for grassland obligate songbirds with narrow habitat preferences during the breeding season, prompting ecologists and conservationists to call for managing rangelands for increased heterogeneity. The Flint Hills also hosts multiple species of conservation concern during winter, but avian habitat requirements are less well known during this period and seldom considered in management recommendations. We investigated the influence of vegetation structure on occurrence of songbirds overwintering at The Nature Conservancy's Tallgrass Prairie Preserve in Osage County, Oklahoma, where fire and grazing are used to increase structural and compositional heterogeneity. During the winters of 2008–2009 and 2009–2010, we used an area-search method to survey 149, 1 ha plots distributed among patches that represented a wide gradient in vegetation structure and 1–3 growing seasons since fire. We modeled occurrence of Le Conte's Sparrow (Ammodramus leconteii), Sedge Wren (Cistothorus platensis), Savannah Sparrow (Passerculus sandwichensis), and Smith's Longspur (Calcarius pictus) with a combination of fine-scale vegetation (e.g., litter depth in sampling plots), landscape-scale factors (e.g., distance to utility poles), and time since fire. Vegetation height was the most consistent predictor for three species, with Le Conte's Sparrow and Sedge Wren associated with tall structure and Smith's Longspur associated with shorter structure. Occurrence of Smith's Longspur was too low to adequately model effects of burn age, but fine-scale vegetation structure used by Le Conte's Sparrow and Sedge Wren was available in plots irrespective of time since fire. A variety of management techniques for creating habitat heterogeneity have the potential to promote grassland songbird diversity during winter, but further study is needed.

Sampling environmental acoustic recordings to determine bird species richness

Acoustic sensors can be used to estimate species richness for vocal species such as birds. They can continuously and passively record large volumes of data over extended periods. These data must subsequently be analyzed to detect the presence of vocal species. Automated analysis of acoustic data for large numbers of species is complex and can be subject to high levels of false positive and false negative results. Manual analysis by experienced surveyors can produce accurate results; however the time and effort required to process even small volumes of data can make manual analysis prohibitive. This study examined the use of sampling methods to reduce the cost of analyzing large volumes of acoustic sensor data, while retaining high levels of species detection accuracy. Utilizing five days of manually analyzed acoustic sensor data from four sites, we examined a range of sampling frequencies and methods including random, stratified, and biologically informed. We found that randomly selecting 120 one-minute samples from the three hours immediately following dawn over five days of recordings, detected the highest number of species. On average, this method detected 62% of total species from 120 one-minute samples, compared to 34% of total species detected from traditional area search methods. Our results demonstrate that targeted sampling methods can provide an effective means for analyzing large volumes of acoustic sensor data efficiently and accurately. Development of automated and semi-automated techniques is required to assist in analyzing large volumes of acoustic sensor data.

An analysis of displacement from wind turbines in a wintering grassland bird community

Wind energy development is rapidly increasing within breeding and wintering ranges of many grassland birds in North America. Despite recognized environmental benefits of such development, wind farms have the potential to negatively impact bird communities. Using an area-search method, we surveyed grassland birds within a matrix of pastures, hay fields, and agricultural lands at a wind facility in north-central Texas during the winters of 2009/10 and 2010/11. We used binary logistic regression to examine the effect of distance from wind turbines on plot occupancy for species that did not show significant habitat associations. In contrast, for species with significant habitat associations, we used a two-step process to test for displacement. First, we identified suitable plots using a niche modeling approach in Maxent. Second, we used binary logistic regression to examine whether distance to turbine influenced the occupancy of those plots. Sprague’s Pipit Anthus spragueii, Savannah Sparrow Passerculus sandwichensis, and meadowlarks Sturnella sp. showed no evidence for displacement. In contrast, the Le Conte’s Sparrow Ammodramus leconteii, was significantly more likely to occupy suitable plots as distance from the nearest turbine increased. Mean plot occupancy for the Le Conte’s Sparrow was more than four times lower in plots 400 m away. Our study highlights the need to investigate displacement at the level of individual species. Our data also suggest that species dependent on cryptic predator evasion strategies may be displaced from wind turbines and this idea warrants further investigation.

Velocity Calculation by Automatic Camera Calibration Based on Homogenous Fog Weather Condition

A novel algorithm for vehicle average velocity detection through automatic and dynamic camera calibration based on dark channel in homogenous fog weather condition is presented in this paper. Camera fixed in the middle of the road should be calibrated in homogenous fog weather condition, and can be used in any weather condition. Unlike other researches in velocity calculation area, our traffic model only includes road plane and vehicles in motion. Painted lines in scene image are neglected because sometimes there are no traffic lanes, especially in un-structured traffic scene. Once calibrated, scene distance will be got and can be used to calculate vehicles average velocity. Three major steps are included in our algorithm. Firstly, current video frame is recognized to discriminate current weather condition based on area search method (ASM). If it is homogenous fog, average pixel value from top to bottom in the selected area will change in the form of edge spread function (ESF). Secondly, traffic road surface plane will be found by generating activity map created by calculating the expected value of the absolute intensity difference between two adjacent frames. Finally, scene transmission image is got by dark channel prior theory, camera?s intrinsic and extrinsic parameters are calculated based on the parameter calibration formula deduced from monocular model and scene transmission image. In this step, several key points with particular transmission value for generating necessary calculation equations on road surface are selected to calibrate the camera. Vehicles? pixel coordinates are transformed to camera coordinates. Distance between vehicles and the camera will be calculated, and then average velocity for each vehicle is got. At the end of this paper, calibration results and vehicles velocity data for nine vehicles in different weather conditions are given. Comparison with other algorithms verifies the effectiveness of our algorithm

Camera calibration based on homogenous fog weather condition

A novel algorithm for automatic and dynamic camera calibration based on dark channel prior in homogenous fog weather condition is presented in this paper. Three main steps are included in the algorithm. Firstly, current weather condition will be judged to justify whether it is homogenous weather condition or not based on area search method (ASE). Secondly, traffic road plane will be found by activity map created by calculating the expected value of the absolute intensity difference between two adjacent frames. Finally, transmission image will be obtained by dark channel prior. Intrinsic and extrinsic parameters of the camera will be calculated based on the parameter calibration formula deduced from camera model and light transition model in fog. In this step eight key points for generating necessary calculation equations in transmission image in road plane will be selected to calibrate the camera. Experiments verify the effectiveness and the robustness of the proposed algorithm.

Bird populations in native forest patches in south-eastern Australia: the roles of patch width, matrix type (age) and matrix use

We surveyed birds in patches of native eucalypt forest and in surrounding exotic matrix (Radiata pine forests) in south-eastern Australia. Our objectives were: (1) to examine the influence of the width of native forest patches and the age of surrounding pine forests on bird occurrence in patches of native forest; and (2) to verify the relationship between the use of the surrounding pine matrix and bird species response to variation in width of patches of native forests. A total of 32 study sites (boundaries between eucalypt and pine forests) were surveyed. Birds were counted by the area search method within 0.5-ha quadrats. Data were analysed using generalised linear models. Wide patches of eucalypt forest supported higher species richness and greater numbers of birds, such as foliage searchers and nectarivores, than narrow patches. Matrix age also influenced the occurrence of some species in native patches. The abundance of species in wide and narrow patches of native forest was related to their use of the matrix. This was true for native forests surrounded by old but not by young pine forests. We suggest that management in wood production landscapes take into account both characteristics of native patches and the surrounding matrix. Negative impacts of fragmentation in managed landscapes might be reduced by promoting matrix types that are suitable for bird species.

The peninsula effect on bird species in native eucalypt forests in a wood production landscape in Australia

AbstractThe peninsula effect – a decrease in species richness from the base to the tip of a peninsula – has been tested for a diverse range of taxa at continental and regional scales. We investigated the peninsula effect at a local scale by examining bird species occurrence in riparian strips (peninsulas) of native eucalypt forest within a radiata pine plantation in the Tumut region, south‐eastern Australia. Peninsulas were elongated but ‘blind’ extensions of a core area of native eucalypt forest. Birds were surveyed by the area search method, within 1.0‐ha quadrats established along peninsulas (n=14), in October and November 2002. Data were analysed using generalized linear mixed models. A significant decrease in bird species richness from the base towards the tip of the peninsulas was observed. The proportion of large bird species recorded per quadrat showed a significant decrease from the base towards the tip of the peninsulas. This pattern was not observed for small birds. Several species were more abundant at the base of the peninsulas than away from the core area of eucalypt forest. The peninsula effect can occur locally in landscape mosaics. Factors leading to the observed patterns of species occurrence may be distinct from those proposed in investigations of the peninsula effect with a biogeographical (macroscale) context. In our microscale study, foraging incursions of individual birds from the core area of native forest through peninsulas were a major factor giving rise to higher bird species richness in the more basal portions of peninsulas.

Comparison of survey methods for wintering grassland birds

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An estimate of population sizes of burrowing seabirds at the Diego Ramirez archipelago, Chile, using distance sampling and burrow-scoping

The Diego Ramirez Islands lie 60 nautical miles southwest of Cape Horn and are the breeding site for three species of burrowing seabirds: blue petrels (Halobaena caerulea), common diving petrels (Pelecanoides urinatrix) and sooty shearwater (Puffinus griseus). Burrowing seabirds are highly vulnerable to predation by introduced vertebrate pests, and Diego Ramirez is an important breeding site because it is one of a few remaining subantarctic island groups with no introduced predators. Diego Ramirez is the only known breeding site for blue petrels in the southeast Pacific region, holding about 80% of the global population of that species, and with a population ten times larger than any other population in the world. We estimated the population size in 2002, using a novel application of the distance sampling technique to determine burrow density, and a burrow-scope with excavations to determine occupying species. We found that density was correlated with slope angle and soil wetness. Burrow densities in flatter terrain with drier soils were 2.03 burrows/m2 (95% confidence intervals: 1.82–2.27) and 1.11 burrows/m2 (0.84–1.48) in steeper terrain with wetter soils. The occupation rate of burrows were significantly different between habitat types (t=2.74, d.f. 11, P<0.05); in flatter drier habitats the proportion of burrows that led to a nest was 0.85 (0.74–0.96), in steeper wetter habitats this decreased to 0.64 (0.50–0.78). We used a digital elevation model to calculate true area rather than planar area for the two habitat types on the main island of Bartolome, and charts to calculate planar area for the remainder of the archipelago. There were 1.35 (1.15–1.54) million pairs of blue petrels and 99,000 (65,000–134,000) pairs of common diving petrels on the archipelago. These are similar figures to those from the only previous estimate, made in 1980. We found breeding sooty shearwaters for the first time, and estimated a population of several thousand pairs. We emphasise the facility of distance sampling as an unbiased technique with practical advantages over commonly used area search methods for monitoring populations of burrowing seabirds. These advantages include increased survey efficiency allowing a larger sample size for a given effort and a correspondingly tighter estimation of density.

Novel patch–matrix interactions: patch width influences matrix use by birds

This study investigated the influence of the width of patches of native eucalypt forest on bird occurrence in stands of exotic radiata pine (Pinus radiata) forests that surrounded such patches. Boundaries between eucalypt and pine forests were surveyed to examine bird occurrence and species richness at different distances in the pine matrix from eucalypt forest edges. Birds were counted by the area search method within 0.5 ha quadrats at 32 study sites (where sites spanned the boundaries of pine and eucalypt forests). Data were examined using generalised linear mixed models. Species richness and occurrence of particular species in quadrats located within pine forests decreased with increasing distance from eucalypt patches. This resulted, in part, from the fact that several species found in native patches also use pine plantations as additional foraging areas. Species richness decreased more quickly with distance from eucalypt patches in younger than in older pine stands. The width of native forest patches also influenced bird occurrence in adjacent pine forest matrix. Bird species richness decreased more rapidly in exotic plantations adjacent to wide rather than narrow patches of native forest. To the best of our knowledge, no studies have previously reported that dimensions of patches can influence the use of surrounding matrix. We introduce the term “halo effect” for the influence of patch attributes on the differential use of matrix adjacent to native patches. These patterns highlight that conservation efforts in patchy environments should protect not only native patches but also adjacent areas of matrix into which animals extend their home ranges.

A field test of the area search method for measuring breeding bird populations

Abstract This paper evaluates the effectiveness of the area search method to measure breeding landbird populations at the plot level. During June 1999, 10 plots in grassland and shelterbelt habitats of north-central South Dakota were surveyed three times using the area search method. The results were then compared with those simultaneously obtained by the spot mapping census method, which served as the standard for comparison. Area searches detected an average of 96.0% of the landbird species present on the grassland plots, and 84.2% of the species on the shelterbelt plots. Species accumulation curves were identical between techniques, suggesting that an increase in number of visits to each plot would likely increase the number of species detected during area search surveys. Estimates of territory density from spot mapping were available for five passerine species. Across all species, area searches underestimated territory densities by an average of 50% when visit data were summarized by taking the averag...

Factors Affecting the Efficiency of the Area Search Method of Censusing Birds in Open Forests and Woodlands

SummaryThis paper examines factors that influence the ability of area searches to census the complete bird population at a site. Such factors included duration and repetition of census periods, density of vegetation, density of individuals of species, weather and time of day. Total time spent on the site was found to be more important than the duration or the number of repetitions of the census period, especially in sites with a dense understorey. In sites with a sparse under-storey, more repetitions of censuses of short duration were more effective. To obtain a complete species list, a total time of around 100 census minutes was required in sparse sites compared with 150 minutes in dense sites. Birds occurring at high density were not necessarily encountered early in the censusing, probably due to their mobility. Increasing wind strength, time after sunrise and minimum temperature adversely affected the number of species found.

Bird Populations in Successional Forests of Mountain Ash Eucalyptus Regnans in Central Victoria

Bird populations were estimated from 1977 to 1979 by mapping territories and by an area search method in stands of differing age (regenerating after wildfire or harvesting eucalypts) in the Victorian Central Highlands mainly near Toolangi. The aims were to assess effects of harvesting (followed by burning and artificial regeneration) and provide data on populations and ecology of birds inhabiting this distinctive forest type. Mountain Ash forests grow in high rainfall areas and the trees can reach heights of 100 m; they usually grow as even-aged stands and 79% of Mountain Ash forests in the Central Highlands has regenerated after severe fires in 1939. About 65 species of birds were found to be regular inhabitants of Mountain Ash forests and associated plant com- munities. All except the Pink Robin breed also in foothill gullies. Several species that are common in drier foothill forests, were absent from Mountain Ash forests. The commonest species were those that feed in the dense shrub layer or from damp ground below. Some insectivorous birds that were abundant in summer (e.g. Golden Whistler Pachycephala pectoralis, Grey Fantail Rhipldura fuliginosa) left Mountain Ash forests for the winter. Winter food sources were limited and the most important were blossoms of Mountain Correa Correa lawrenclana, invertebrates in damp leaf litter, and invertebrates or carbohydrate exudates from hanging bark of Mountain Ash or branches and trunks of Silver Wattle Acacia dealbata. Habitats and interactions between various bird species are described. Bird population densities were low in the first three years after harvesting but some species were confined to open stands of this age. Other forest birds returned rapidly as eucalypts and understorey species regenerated. Populations were as high in 39-year-old regrowth as in older stands though some species (mainly those that need tree hollows for nesting) were more common in older forest. Implications for management are discussed.