Showing papers on "Occupancy published in 2007"
TL;DR: A hierarchical parameterization of dynamic occupancy models is described that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process.
Abstract: Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by non-detection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and WinBUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site-specific heterogeneity in model parameters. The results indicate relatively low turnover and a stable distribution of Cerulean Warblers which is in contrast to analyses of counts of individuals from the same survey that indicate important declines. This discrepancy illustrates the inertia in occupancy relative to actual abundance. Furthermore, the model reveals a declining patch survival probability, and increasing turnover, toward the edge of the range of the species, which is consistent with metapopulation perspectives on the genesis of range edges. Given detection/non-detection data, dynamic occupancy models as described here have considerable potential for the study of distributions and range dynamics.
375 citations
TL;DR: A comprehensive assessment of continental-scale fire patterning (1997-2005) derived from ∼ 1k m 2 AdvancedVery High Resolution Radiometer (AVHRR) imagery shows that fire activity occurs predominantly in the savanna landscapes of monsoonal northern Australia as mentioned in this paper.
Abstract: Australia is among the most fire-prone of continents. While national fire management policy is focused on irregular and comparatively smaller fires in densely settled southern Australia, this comprehensive assessment of continental-scale fire patterning (1997-2005) derived from ∼ 1k m 2 AdvancedVery High Resolution Radiometer (AVHRR) imagery shows that fire activity occurs predominantly in the savanna landscapes of monsoonal northern Australia. Sta- tistical models that relate the distribution of large fires to a variety of biophysical variables show that, at the continental scale, rainfall seasonality substantially explains fire patterning. Modelling results, together with data concerning seasonal lightning incidence, implicate the importance of anthropogenic ignition sources, especially in the northern wet-dry tropics and arid Australia, for a substantial component of recurrent fire extent. Contemporary patterns differ markedly from those under Aboriginal occupancy, are causing significant impacts on biodiversity, and, under current patterns of human popula- tion distribution, land use, national policy and climate change scenarios, are likely to prevail, if not intensify, for decades to come. Implications of greenhouse gas emissions from savanna burning, especially seasonal emissions of CO2, are poorly understood and contribute to important underestimation of the significance of savanna emissions both in Australian and probably in international greenhouse gas inventories. A significant challenge for Australia is to address annual fire extent in fire-prone Australian savannas.
258 citations
TL;DR: It is recommended that researchers studying habitat occupancy and habitat selection consider how events in previous seasons influence events within a season.
Abstract: Abstract. Historically, studies of habitat selection have focused on quantifying how current patterns of habitat occupancy influence condition and survival within a season. This approach, however, is overly simplistic, especially for migratory birds that spend different periods of the year in geographically distinct places. Habitat occupancy and the resulting condition of individual birds is likely to be affected by events in the previous season, and the consequences of habitat occupancy will influence individuals and populations in subsequent seasons. Thus, for migratory birds, variation in habitat quality (and quantity) needs to be understood in the context of how events interact throughout periods of the annual cycle. Seasonal interactions can occur at the individual level or population level. Individual-level interactions occur when events in one season produce nonlethal, residual effects that carry over to influence individuals the following season. Population-level interactions occur when a...
249 citations
TL;DR: S suite of questions commonly encountered during the design phase of occupancy studies are discussed, and software developed to allow investigators to easily explore design trade-offs focused on particularities of their study system and sampling limitations are described.
Abstract: Researchers have used occupancy, or probability of occupancy, as a response or state variable in a variety of studies (e.g., habitat modeling), and occupancy is increasingly favored by numerous state, federal, and international agencies engaged in monitoring programs. Recent advances in estimation methods have emphasized that reliable inferences can be made from these types of studies if detection and occupancy probabilities are simultaneously estimated. The need for temporal replication at sampled sites to estimate detection probability creates a trade-off between spatial replication (number of sample sites distributed within the area of interest/inference) and temporal replication (number of repeated surveys at each site). Here, we discuss a suite of questions commonly encountered during the design phase of occupancy studies, and we describe software (program GENPRES) developed to allow investigators to easily explore design trade-offs focused on particularities of their study system and sampling limitations. We illustrate the utility of program GENPRES using an amphibian example from Greater Yellowstone National Park, USA.
232 citations
TL;DR: This work characterizes occupied locations in California Spotted Owls by characterizing occupied locations by some additional state variable (e.g., as producing young or not), and deals with both detection probabilities <1 and uncertainty in state classification.
Abstract: The distribution of a species over space is of central interest in ecology, but species occurrence does not provide all of the information needed to characterize either the well-being of a population or the suitability of occupied habitat. Recent methodological development has focused on drawing inferences about species occurrence in the face of imperfect detection. Here we extend those methods by characterizing occupied locations by some additional state variable (e.g., as producing young or not). Our modeling approach deals with both detection probabilities <1 and uncertainty in state classification. We then use the approach with occupancy and reproductive rate data from California Spotted Owls (Strix occidentalis occidentalis) collected in the central Sierra Nevada during the breeding season of 2004 to illustrate the utility of the modeling approach. Estimates of owl reproductive rate were larger than naive estimates, indicating the importance of appropriately accounting for uncertainty in detection and state classification.
189 citations
TL;DR: In this article, the authors applied a detection/non-detection sampling technique using camera trap data with environmental covariates to estimate sun bear occupancy from three tropical forest study areas in Sumatra.
182 citations
TL;DR: The occupancy histories of Cenozoic marine mollusks from New Zealand show a distinct pattern of increase to relatively short-lived peak occupancy at mid-duration, followed by a decline toward extinction.
Abstract: In the time between speciation and extinction, a species' ecological and biogeographic footprint-its occupancy-will vary in response to macroecological drivers and historical contingencies. Despite their importance for understanding macroecological processes, general patterns of long-term species occupancy remain largely unknown. We documented the occupancy histories of Cenozoic marine mollusks from New Zealand. For both genera and species, these show a distinct pattern of increase to relatively short-lived peak occupancy at mid-duration, followed by a decline toward extinction. Thus, species at greatest risk for extinction are those that have already been in decline for a substantial period of time. This pattern of protracted rise and fall stands in contrast to that of incumbency, insofar as species show no general tendency to stay near maximal occupancy once established.
148 citations
TL;DR: This study suggests that the amphibian populations the authors studied are resistant to wildfire and that B. boreas may experience short-term benefits from wildfire, and illustrates how naive presence-non-detection data can provide misleading results.
Abstract: Wildland fires are expected to become more frequent and severe in many ecosystems, potentially posing a threat to many sensitive species. We evaluated the effects of a large, stand-replacement wildfire on three species of pond-breeding amphibians by estimating changes in occupancy of breeding sites during the three years before and after the fire burned 42 of 83 previously surveyed wetlands. Annual occupancy and colonization for each species was estimated using recently developed models that incorporate detection probabilities to provide unbiased parameter estimates. We did not find negative effects of the fire on the occupancy or colonization rates of the long-toed salamander (Ambystoma macrodactylum). Instead, its occupancy was higher across the study area after the fire, possibly in response to a large snowpack that may have facilitated colonization of unoccupied wetlands. Naive data (uncorrected for detection probability) for the Columbia spotted frog (Rana luteiventris) initially led to the conclusion of increased occupancy and colonization in wetlands that burned. After accounting for temporal and spatial variation in detection probabilities, however, it was evident that these parameters were relatively stable in both areas before and after the fire. We found a similar discrepancy between naive and estimated occupancy of A. macrodactylum that resulted from different detection probabilities in burned and control wetlands. The boreal toad (Bufo boreas) was not found breeding in the area prior to the fire but colonized several wetlands the year after they burned. Occupancy by B. boreas then declined during years 2 and 3 following the fire. Our study suggests that the amphibian populations we studied are resistant to wildfire and that B. boreas may experience short-term benefits from wildfire. Our data also illustrate how naive presence-non-detection data can provide misleading results.
78 citations
TL;DR: This study shows that a profitable approach to ascertaining the nature of human impacts is to link intra- and interspecific processes, in the case of British farmland and woodland birds, changes to the environment lead to species-specific responses in large-scale distributions.
Abstract: 1. Range size, population size and body size, the key macroecological variables, vary temporally both within and across species in response to anthropogenic and natural environmental change. However, resulting temporal trends in the relationships between these variables (i.e. macroecological patterns) have received little attention. 2. Positive relationships between the local abundance and regional occupancy of species (abundance-occupancy relationships) are among the most pervasive of all macroecological patterns. In the absence of formal predictions of how abundance-occupancy relationships may vary temporally, we outline several scenarios of how changes in abundance within species might affect interspecific patterns. 3. We use data on the distribution and abundance of 73 farmland and 55 woodland bird species in Britain over a 32-year period encompassing substantial habitat modification to assess the likelihood of these scenarios. 4. In both farmland and woodland habitats, the interspecific abundance-occupancy relationship changed markedly over the period 1968-99, with a significant decline in the strength of the relationship. 5. Consideration of intraspecific dynamics shows that this has been due to a decoupling of abundance and occupancy particularly in rare and declining species. Insights into the intraspecific processes responsible for the interspecific trend are obtained by analysis of temporal trends in the distribution of individuals between sites, which show patterns consistent with habitat quality declines. 6. This study shows that a profitable approach to ascertaining the nature of human impacts is to link intra- and interspecific processes. In the case of British farmland and woodland birds, changes to the environment lead to species-specific responses in large-scale distributions. These species-specific changes are the driver of the observed changes in the form and strength of the interspecific relationship.
67 citations
TL;DR: Recently developed statistical approaches incorporating detection uncertainty are applied to characterize the spatial dynamics of an invasive bird species, the Eurasian collared dove (Streptopelia decaocto).
Abstract: Aim The study of the spatial dynamics of invasive species is a key issue in invasion ecology. While mathematical models are useful for predicting the extent of population expansions, they are not suitable for measuring and characterizing spatial patterns of invasion unless the probability of detection is homogeneous across the distribution range. Here, we apply recently developed statistical approaches incorporating detection uncertainty to characterize the spatial dynamics of an invasive bird species, the Eurasian collared dove (Streptopelia decaocto).
Location France.
Methods Data on presence/absence of doves were recorded from 1996 to 2004 over 1045 grid cells (28 × 20 km) covering the entire country. Each grid cell included five point counts spaced along a route, which was visited twice a year, allowing for an estimation of detection probability. Each route was assigned to one of six geographical regions. We used robust design occupancy analysis to assess spatial and temporal variation in parameters related to the spatial dynamics of the species. These parameters included occupancy rate, colonization and local extinction probabilities. Our inference approach was based on the selection of the most parsimonious model among competitive models parametrized with conditional probabilities.
Results The probability of detecting the presence of doves on a given route was high. However, we found evidence to incorporate detection uncertainty in inference processes about spatial dynamics, since detection probability was neither perfect (i.e. it was < 1), nor constant over space and time. Results showed a clear positive trend in occupancy rate over the study period, increasing from 55% in 1996 to 76% in 2004. In addition, occupancy rate differed among regions (range: 37–79%) and further analysis showed that colonization probability by region was positively related to occupancy rate. Finally, local extinction probability was lower than colonization probability and showed a tendency to decrease over the study period.
Main conclusions Our results emphasize the importance of estimating detection probabilities in order to draw proper inferences about the spatial and temporal dynamics of the invasion pattern of the collared dove. In contrast to the perceived spatial dynamics from national atlas surveys, we provide evidence that the range of this species is currently increasing in France. Other results, such as regional specificity in colonization probabilities and time variation in local extinction are consistent with expectations from invasion and metapopulation theory.
64 citations
TL;DR: The approach in building a computerized model to provide short-term occupancy predictions for an entire hospital by nursing unit and shift and the results and accuracy are compared to a variety of other predictive methods based on tests using 2 years of actual hospital data.
Abstract: Inpatient census, or occupancy, is a primary driver of resource use in hospitals. Fluctuations in occupancy complicate decisions related to staffing, bed management, ambulance diversions, and may ultimately impact both quality of patient care and nursing job satisfaction. We describe our approach in building a computerized model to provide short-term occupancy predictions for an entire hospital by nursing unit and shift. Our model is a comprehensive system built using real hospital data and utilizes statistical predictions at the individual patient level. We discuss the results of piloting an early version of the model at a mid-size community hospital. The primary focus of the paper is on the development and methodology of a second generation of the predictive occupancy model. The results and accuracy of this new model is compared to a variety of other predictive methods based on tests using 2 years of actual hospital data.
01 Dec 2007
TL;DR: A probabilistic model for predicting the occupancy of a building using networks of people-counting sensors that provides robust predictions given typical sensor noise as well as missing and corrupted data from malfunctioning sensors is described.
Abstract: Knowledge of the number of people in a building at a given time is crucial for applications such as emergency response. Sensors can be used to gather noisy measurements which when combined, can be used to make inferences about the location, movement and density of people. In this paper we describe a probabilistic model for predicting the occupancy of a building using networks of people-counting sensors. This model provides robust predictions given typical sensor noise as well as missing and corrupted data from malfunctioning sensors. We experimentally validate the model by comparing it to a baseline method using real data from a network of optical counting sensors in a campus building.
TL;DR: In this article, the importance of human activity and ecological features in influencing African forest elephant ranging behavior was investigated in the Rabi-Ndogo corridor of the Gamba Complex of Protected Areas in southwest Gabon.
TL;DR: In this paper, the authors examined whether patterns in geographical range occupancy can be explained by species-level traits and found three species traits that together explained more than half of the variation in range occupancy.
Abstract: Aim The degree to which a species is predictably encountered within its range varies tremendously across species. Understanding why some species occur less frequently within their range than others has important consequences for conservation and for analyses of ecological patterns based on range maps. We examined whether patterns in geographical range occupancy can be explained by species-level traits. Location North America. Methods We used survey data from 1993 to 2002 from the North American Breeding Bird Survey along with digital range maps produced by NatureServe to calculate range occupancy for 298 species of terrestrial birds. We tested whether species traits explained variation in range occupancy values using linear regression techniques. Results We found three species traits that together explained more than half of the variation in range occupancy. Population density and niche breadth were positively correlated with occupancy, while niche position was negatively correlated with occupancy. Main conclusions Our results suggest that high range occupancy will occur in species that are common at sites on which they occur, that tolerate a relatively wide range of ecological conditions and that tend to have ranges centred on areas with common environmental conditions. Furthermore, it appears that niche-based characteristics may explain patterns of distribution and abundance from local habitats up to the scale of geographical ranges.
TL;DR: In this paper, the authors developed a facility coefficient aiming to adjust the allocation of maintenance resources to prevailing service conditions in healthcare facilities, using deterioration patterns and predicted service lives of building components and systems under moderate, standard and intensive occupancy and under two categories of environment: marine and inland.
Abstract: Global competitiveness and increasing performance requirements have placed facilities management (FM) under constraints of limited resources, particularly in non‐core aspects of facilities, such as maintenance and operations. The hypothesis applied in this research is that the actual service life of buildings, their occupancy and their ambient environmental conditions affect the required maintenance resources of these facilities. The objective was to develop a facility coefficient aiming to adjust the allocation of maintenance resources to prevailing service conditions in healthcare facilities. The research uses deterioration patterns and predicted service lives of building components and systems under moderate, standard and intensive occupancy and under two categories of environment: marine and inland. In total, five configurations combining occupancy and environmental conditions were investigated through simulations and compared to a reference configuration defined as standard occupancy and inland envir...
01 Jul 2007
TL;DR: In this article, the authors used existing measures and methods to describe patchiness and scale effect for predicting distribution at fine scales from coarse scales, which can capture the spatial features of species distribution.
Abstract: Introduction Species occupancy is typically measured as the number of cells occupied by the species in a study area. Because it is easy to document and interpret and it correlates with species abundance, occupancy is widely used for measuring species rarity and for assessing extinction risk on which conservation decisions are made (Gaston, 1994; Fagan et al ., 2002; Hartley & Kunin, 2003; Wilson et al ., 2004). Ecologists and conservation practitioners, however, have long realized that occupancy often fails to capture significant spatial features of distribution. It is possible that two species having the same occupancy can exhibit very different patterns (Fig. 3.1). Most species in nature are discretely distributed due to the patchiness of landscapes, or due to intrinsic reproductive or dispersal behavior of the species. An outstanding problem concerning species distribution in space is how to describe the patchiness of a species and to measure the effect of changing spatial scale (cell size) on the patchiness for the purpose of predicting distribution at fine scales from coarse scales. There are two primary approaches to addressing this question. The first one is to use existing measures and methods to describe patchiness and scale effect. Many fragmentation indices in landscape ecology can be used for this purpose (Turner, Gardner & O'Neill, 2001; Wu et al ., 2003). These include edge length (perimeter), the number of patches, perimeter/area ratio and many other indices to capture the spatial features of species distribution.
TL;DR: This paper examined the effect of prescribed fire on beaver lodge occupancy in the context of high ungulate populations and found that repeated burning dramatically decreases beaver occupancy, and that even after one burn the number of active colonies declines and does not recover to pre-fire populations.
TL;DR: In this article, the authors used Generalized Additive Modelling (GAM) to build a predictive distribution model using Geographic Information System (GIS) coverages and satellite imagery, and then applied the model retrospectively to a time series of satellite images to produce one distribution map for each year.
Abstract: Variations in habitat quality impact on breeding success, leading to strong selection pressure for the best sites to be occupied first during a population increase and last during a decline. Coupled with dispersal and metapopulation processes, the result is that snapshot surveys of wildlife distributions may fail to reveal core areas that conservation seeks to protect. At a local scale, territory occupancy is a good indicator of quality but data are not readily available to assess occupancy for rarer species, in remote areas, and over large spatial extents. We introduce temporal suitability analysis as a way to generate an analogue of occupancy from a single survey and illustrate it using data on the little bustard in Spain. We first used Generalised Additive Modelling (GAM) to build a predictive distribution model using Geographic Information System (GIS) coverages and satellite imagery, and then applied the model retrospectively to a time series of satellite images to produce one distribution map for each year. These annual maps differed in the extent of Spain predicted as suitable for little bustards. By overlaying the maps, we identified areas predicted as suitable in one to n years. We show that this temporal suitability map correlates with a conventional habitat suitability map based on a single year but contains extra information on hierarchical use of habitats and the lag between suitability and use. The technique may be applied at a variety of spatial scales to reveal changes in expected occupancy as land use or external factors determining land cover types vary over time.
TL;DR: A metapopulation model for successional-type systems, in which habitat quality changes over time in a predictable fashion is developed, which predicted observed spatial distributions better than a similar model that assumed constant habitat quality of each forest stand.
Abstract: Because of the dynamic nature of many managed habitats, proper evaluation of conservation efforts calls for models that take into account both spatial and temporal habitat dynamics. We develop a metapopulation model for successional-type systems, in which habitat quality changes over time in a predictable fashion. The occupancy and recruitment of the predatory saproxylic (dependent on dead wood) beetle Harminius undulatus was studied in a managed boreal forest landscape, covering 24 449 ha, in central Sweden. In a first step, we analyzed the beetle's occupancy pattern in relation to stand characteristics, and the amounts of present and past habitat in the surrounding landscape. Managed forest is suitable habitat when ≥60 years old, and immediately after cutting, but not between the ages of 10 and 60 years. The observed occupancy of H. undulatus was positively correlated with the stand's age as habitat. We used a metapopulation model to predict the current probability of occurrence in each forest stand, gi...
TL;DR: In this paper, the effects of fire on the federally endangered Cape Sable seaside sparrow in Everglades National Park were investigated using a before-after-control-impact study design.
TL;DR: In this paper, the authors explored several scenarios based on combinations of six parameters defining biogeographical and cartographic factors typically encountered by investigators to assess the implications of errors of commission when developing and applying range overlap maps, using neutral landscapes to simulate range maps and patterns of occupancy within ranges.
Abstract: Range maps are often combined into "range overlap maps" to estimate spatial variation in species richness. Range maps are, in most cases, designed to represent a species' maximum geographical extent and not patterns of occupancy within the range. As a consequence, range maps overestimate occupancy by presenting false occupancy (errors of commission) within the interior of the range. To assess the implications of errors of commission when developing and applying range overlap maps, we used neutral landscapes to simulate range maps and patterns of occupancy within ranges. We explored several scenarios based on combinations of six parameters defining biogeographical and cartographic factors typically encountered by investigators. Our results suggest that, in general, uncertainty is lowest when map resolutions are moderately fine, the majority of species have geographically restricted ranges, species occur throughout their range, patterns of occupancy within the range are not correlated among species, and geographically local and widespread species tend to occupy different regions. Several of these outcomes are associated with broad geographical extents, the scale at which range overlap maps are typically applied. Thus, under most circumstances, reasonably accurate and precise representation of species richness patterns can be achieved. However, these representations can be improved by enhancing occupancy data for widespread species - a primary source of uncertainty - and selecting a map resolution that captures relevant biological and environmental heterogeneity. Hence, by determining where a study is situated within the scenarios examined in our simulations, uncertainty and its sources and implications can be ascertained. With this knowledge, research goals, methods, and data sources can be reassessed and refined and, in the end, conclusions and recommendations can be qualified. Alternatively, unique regional, taxonomic, or cartographic factors could be included in future simulations to provide direct assessments of uncertainty.
Journal Article•
TL;DR: For conservation of the ortolan bunting, the maintenance and improvement of structurally and biologically diverse habitats is vital, since tendency to breed in groups apparently makes the species more sensitive to habitat changes than many other farmland species.
Abstract: We studied the relationships between the occupancy of territory sites and environmental and behaviour-related factors in a declining farmland bird, the ortolan bunting Emberiza hortulana, in southern Finland in 1984-2003. We investigated the dependence of different factors on population density. The surrounding breeding group positively affected the occupation frequency of territory sites before and after the population crash. Bush- or tree-covered ditches and springtime non-vegetated fields also had positive effect on territory site occupancy. We suggest that large breeding groups, and obvious conspecific attraction, give indications of favourable breeding locations. Habitat deterioration may have pronounced consequences for local populations, in which the breeding group tends to be the unit of population dynamics. The results suggest that for conservation of the ortolan bunting, the maintenance and improvement of structurally and biologically diverse habitats is vital, since tendency to breed in groups apparently makes the species more sensitive to habitat changes than many other farmland species.
TL;DR: An occupancy probability transition (OPT) model is presented to investigate the effect of sampling scale and species saturation on the shape of occupancy frequency distributions and demonstrates that the sample grain of a study, sampling adequacy and the distribution of species saturation coefficients in a community are together largely able to explain the patterns observed in empirical occupancy frequency distribution.
TL;DR: Butterfly range occupancy across species is low and variable, ranging from 1% to 37% among species present in the authors' sample, demonstrating potential practical and conceptual challenges inherent in the use of range maps to assess endangerment and conservation priority.
Abstract: Conservation efforts are frequently hampered by uncertainty regarding species' distributions. Range maps as representations of species distributions are known to overestimate the area occupied by the species, with significant implications for the prioritization of conservation efforts among species. We investigate the disparity between extent of occurrence (i.e., “range”) and area of occupancy of a population or species and discuss its implications. Using as a test group a community of subalpine butterflies (Lepidoptera: Papilionoidea), we estimated range occupancy based on three levels of analysis: two field guides with differing mapped resolution of range and microdistribution data collected in the vicinity of the Rocky Mountain Biological Laboratory, near Crested Butte, Gunnison County, Colorado. We conclude butterfly range occupancy across species is low and variable, ranging from 1% to 37% among species present in our sample. A large proportion of species identified as present by range maps ...
01 Jan 2007
TL;DR: In this paper, the authors applied a maximum likelihood approach to estimate probability of site occupancy using acoustic detection data for ten species of forest bats in the Ozark Region of Missouri, and evaluated a priori hypotheses relative to both probability of detection and site occupancy.
Abstract: The ecological importance of bat populations and their susceptibility to decline emphasizes the need for scientifically rigorous yet economically feasible approaches to assessing bat habitat occupancy patterns, and relative abundance at multiple scales over time. Historically, many such studies have not accounted for imperfect detection probability. Because bats are difficult to detect by either capture or acoustic methods, without consideration of detection probability, inferences for population trends has been problematic. We applied a maximum likelihood approach to estimate probability of site occupancy using acoustic detection data for ten species of forest bats in the Ozark Region of Missouri. We evaluated a priori hypotheses relative to both probability of detection and site occupancy using an objective model selection criterion (Akaike's Information Criteria, AIC) to rank the candidate models in terms of their ability to explain the empirical data. Estimated species-specific detection probabilities varied among species. We found support for the effects of time, ambient temperature, days since last rain, vegetative clutter, and date on detection probability. Species responded to landscape pattern at different spatial scales (2, 8, and 16 km). Habitat, patch and landscape characteristics (i.e.,
TL;DR: Patch size was a strong predictor of the persistence of speckled warblers in habitat remnants and the need for studies of demography in different regions to interpret regional patterns of occupancy and to identify mechanisms of decline in remnant habitat is highlighted.
TL;DR: In this article, an unusually long-term survey has been conducted across this subspecies' entire range, and the information contained in the survey was treated as presence-absence data and evaluated occupancy trends through time.
01 Jan 2007
TL;DR: In this article, a systematic approach toward obtaining, analyzing, and simulation-based reproduction of performance data from traditional buildings is presented, which involves long-term data collection regarding local climate, indoor conditions in the selected building objects, construction methods, building materials, energy systems, ventilation regimes, and occupancy patterns.
Abstract: A systematic approach toward obtaining, analyzing, and simulation-based reproduction of performance data from traditional buildings is presented. This approach involves long-term data collection regarding local climate, indoor conditions in the selected building objects, construction methods, building materials, energy systems, ventilation regimes, and occupancy patterns. Subsequently, the collected data is analyzed and interpreted in view of the buildings’ salient design features. Furthermore, a digital performance simulation model of the building is generated and calibrated based on collected indoor climate data. The approach is exemplified using the instance of a traditional hammam building located in Cairo, Egypt.
01 Jan 2007
TL;DR: The goal of the project was to design an occupancy sensor system that determines if there exists more than one person in a defined region and testing and evaluation of the system proved it to be sound.
Abstract: This masters thesis project, "Occupancy Sensor System", was conducted at Kungliga Tekniska Hogskolan (KTH), Stockholm, Sweden, during the period 2007-04-24 – 2007-12-17. The goal of the project was to design an occupancy sensor system that determines if there exists more than one person in a defined region. The output of this system is for use in a context-aware system at the KTH Center for Wireless Systems (Wireless@KTH). The system is important because there is a need for specific input to context-aware systems concerning occupancy of spaces and because this thesis has focused on a problem that enables new complex and interesting services. Additionally, the specific problem of determining not only occupancy, but if this occupancy is zero, one, many has not been widely examined previously. The significance of zero occupants indicating an empty room has already been recognized as having economic and environmental value in terms of heating, ventilating, air-conditioning, and lighting. However, there has not been an effort to differentiate between a person being alone or if more than one person is present. A context-aware system might be able to use this later information to infer that a meeting is taking place in a meeting room, a class taking place in a classroom or that an individual is alone in a conference room, class room, etc. Thus enabling context-aware services to change their behavior based upon the differences in these situations. An occupancy sensor system prototype was designed to monitor a boundary by using a thermal detector, gumstix computer, an analog to digital converter prototype board, laptop computer, and a context broker. The testing and evaluation of the system, proved it to be sound. However, there are still further improvements and tests to be made. These improvements include: dynamic configuration of the system, communication between the different system entities, detection algorithms, and code improvements. Tests measuring accuracy of a detection algorithm and determining optimal detector placement need to be performed. The next step is to design applications that use the context information provided from the occupancy sensor system and expand the system to use multiple detectors.