Showing papers on "Occupancy published in 2002"

Avian persistence in fragmented rainforest.

Abstract: What factors determine the persistence of species in fragmented habitats? To address this question, we studied the relative impacts of forest deterioration and fragmentation on bird species in 12 rainforest fragments in Kenya, combining 6 years of individual capture-recapture data with measurements of current captures and museum specimens. Species mobility, as estimated from species-specific dispersal rates, and tolerance to habitat deterioration, as estimated from change in fluctuating asymmetry with increasing habitat disturbance, explained 88% of the variation in patch occupancy among eight forest bird species. Occupancy increased with mobility and with tolerance to deterioration, where both variables contributed equally to this relationship. We conclude that individual-level study, such as of dispersal behavior and phenotypic development, can predict patterns of persistence at the species level. More generally, for conservation tactics to stand a high chance of success, they should include action both within sites, to minimize habitat deterioration, and across landscapes, to maximize dispersal.

Occupancy frequency distributions: patterns, artefacts and mechanisms.

Abstract: Numerous hypotheses have been proposed to explain the shape of occupancy frequency distributions (distributions of the numbers of species occupying different numbers of areas). Artefactual effects include sampling characteristics, whereas biological mechanisms include organismal, niche-based and meta-population models. To date, there has been little testing of these models. In addition, although empirically derived occupancy distributions encompass an array of taxa and spatial scales, comparisons between them are often not possible because of differences in sampling protocol and method of construction. In this paper, the effects of sampling protocol (grain, sample number, extent, sampling coverage and intensity) on the shape of occupancy distributions are examined, and approaches for minimising artefactual effects recommended. Evidence for proposed biological determinants of the shape of occupancy distributions is then examined. Good support exists for some mechanisms (habitat and environmental heterogeneity), little for others (dispersal ability), while some hypotheses remain untested (landscape productivity, position in geographic range, range size frequency distributions), or are unlikely to be useful explanations for the shape of occupancy distributions 'species specificity and adaptation to habitat, extinction-colonization dynamics). The presence of a core (class containing species with the highest occupancy) mode in occupancy distributions is most likely to be associated with larger sample units, and small homogenous sampling areas positioned well within and towards the range centers of a sufficient proportion of the species in the assemblage. Satellite (class with species with the lowest occupancy) modes are associated with sampling large, heterogeneous areas that incorporate a large proportion of the assemblage range. However, satellite modes commonly also occur in the presence of a core mode, and rare species effects are likely to contribute to the presence of a satellite mode at most sampling scales. In most proposed hypotheses, spatial scale is an important determinant of the shape of the observed occupancy distribution. Because the attributes of the mechanisms associated with these hypotheses change with spatial scale, their predictions for the shape of occupancy distributions also change. To understand occupancy distributions and the mechanisms underlying them, a synthesis of pattern documentation and model testing across scales is thus needed. The development of null models, comparisons of occupancy distributions across spatial scales and taxa, documentation of the movement of individual species between occupancy classes with changes in spatial scale, as well as further testing of biological mechanisms are all necessary for an improved understanding of the distribution of species and assemblages within their geographic ranges.

Pattern does not equal process: what does patch occupancy really tell us about metapopulation dynamics?

Abstract: Patch occupancy surveys are commonly used to parameterize metapopulation models. If isolation predicts patch occupancy, this is generally attributed to a balance between distance-dependent recolonization and spatially independent extinctions. We investigated whether similar patterns could also be generated by a process of spatially correlated extinctions following a unique colonization event (analogous to nonequilibrium processes in island biogeography). We simulated effects of spatially correlated extinctions on patterns of patch occupancy among pikas (Ochotona princeps) at Bodie, California, using randomly located extinction disks to represent the likely effects of predation. Our simulations produced similar patterns to those cited as evidence of balanced metapopulation dynamics. Simulations using a variety of disk sizes and patch configurations confirmed that our results are potentially applicable to a broad range of species and sites. Analyses of the observed patterns of patch occupancy at Bodie revealed little evidence of rescue effects and strong evidence that most recolonizations are ephemeral in nature. Persistence will be overestimated if static or declining patterns of patch occupancy are mistakenly attributed to dynamically stable metapopulation processes. Consequently, simple patch occupancy surveys should not be considered as substitutes for detailed experimental tests of hypothesized population processes, particularly when conservation concerns are involved.

Temporal occupancy grids: a method for classifying the spatio-temporal properties of the environment

Abstract: This paper introduces the concept of a temporal occupancy grid as a method for modeling and classifying spatial areas according to the time properties of their occupancy. The method extends the idea of occupancy grids by considering occupancy over a number of different timescales. This paper presents the basic formalism and its implementation using planar laser rangefinders. It includes the results of a number of validation experiments, and an experiment in which we demonstrate the ability to locate doors in a real-world setting.

Predicting occupancy for the siberian flying squirrel in old-growth forest patches

Abstract: Management and conservation efforts necessitate the understanding of species' habitat requirements at the local scale. Population processes, however, often operate at larger scales than a single habitat patch and therefore, attention should be given to species' landscape responses in a network of habitat patches. The aim of this study was to determine important landscape characteristics associated with patch occupancy of the Siberian flying squirrel in northern Finnish forest landscapes. Landscape data were derived from satellite images and analyzed in GIS. Having landscape measures as independent explanatory variables, we developed a predictive landscape model using logistic regression analysis. Our model pointed out the relative importance of landscape characteristics such as the amount and quality of preferred habitat and the degree of structural connectivity at a local scale. Our landscape model was correct in predicting 80% of species occupancy. We further tested model predictions with an independent data set for another landscape in northern Finland. The model did not predict occupied habitat patches as accurately as unoccupied ones in this test area, suggesting limitations and the need for caution in the application of the model elsewhere in northern Finland. This may be due to inherent landscape patterns and/or population processes that vary among study areas in the region. This finding suggests that predictive models should be constructed for spatially explicit domains where the changes in, for instance, soil characteristics and topography vary within certain limits and can be controlled. Nevertheless, our model provides a useful tool for landscape ecological forest planning to locate potential habitat patches and assess the quality and spacing of connecting habitat in the matrix.

What Makes for a Successful Hotel? Insights on Hotel Management Following 15 Years of Hotel Occupancy Analysis in England

Abstract: Time series analyses of daily and monthly occupancy rates in different samples of hotels in England over a 15-year period reveal consistent temporal components of occupancy performance. These differentiate hotels in terms of overall occupancy levels, seasonality, length of season, trend and within-week variations. The components are related to the characteristics of hotels and their management using statistical methods and structured interview surveys, and the factors affecting occupancy performance of hotels are identified and calibrated. The policy implications for the results for successful hotel marketing and management are extracted.

Effects of landscape and local habitat attributes on northern goshawk site occupancy in western Washington

Abstract: We quantified habitat structure, composition, and configuration at three spatial scales (39 ha nest area; 177 ha post-fledging area; 1,886 ha home range) and compared vegetative conditions with measures of northern goshawk (Accipiter gentilis) site occupancy at 30 historical nest sites (those containing at least one goshawk and a large stick nest when discovered) on Washington's Olympic Peninsula. Twelve of the 30 historical sites were occupied by one or more goshawks and 8 of the 12 contained a successful breeding pair. Sites that were occupied in 1 yr tended to remain occupied throughout the 3 yr study, and breeding success was strongly and positively correlated with occupancy. Occupied historical sites tended to have a high proportion of late-seral forest [>70% canopy closure of conifer species with >10% of the canopy trees >53 cm diameter at breast height (dbh)], reduced stand initiation cover, and reduced landscape heterogeneity at all three scales, but only the two larger scale models predicted occupancy successfully. Incorporating habitat attributes previously measured at finer (stand level) scales (canopy depth and percent shrub cover in the nest stand) improved our larger (landscape level) scale models of goshawk occupancy. Olympic Peninsula forest managers can promote goshawk occupancy, and therefore reproduction, by limiting the amount of early forest stand initiation cover ( 39 ha) having deep canopies and reduced shrub cover.

Predicting the implications of conservation management: a territorial occupancy model of Bonelli's eagle in Murcia, Spain

Abstract: Bonelli's eagle Hieraaetus fasciatus is a for the species. The model, which assumes demographic stability, estimates an equilibrium proportion of habitat threatened cliC-nesting raptor mainly distributed in the coastal regions of the Mediterranean. The European occupancy as a function of life history parameters, dispersal behaviour and habitat suitability. In spite of population has declined and the species is considered Vulnerable in Spain. Before eCective conservation pro- some limitations the model identified the most important conservation measures required for an increase in the grammes can be proposed the causes of this decline need to be considered. In a monitoring programme of the proportion of territories occupied: the improvement of the survival of both territorial and non-territorial birds, population of Bonelli's eagle in Murcia carried out since 1983 we observed a marked decline, followed by a period and an increase in the proportion of suitable habitat. of stability that began in 1990. Using demographic data (territorial bird survival, non-territorial bird survival, Keywords Bonelli's eagle, demography, Hieraaetus fasciatus, management, Mediterranean, Spain, survival, and fecundity) for 1990-1998 we applied a territorial occupancy model to evaluate management alternatives territorial occupancy model.

Does Northern Goshawk breeding occupancy vary with nest-stand characteristics on the Olympic Peninsula, Washington?

Abstract: —^We studied foraging ecology of nesting Bald Eagles (Haliaeetus leucocephalus) in Arizona during 1987-89, with emphasis on the influence of dams and river flow regulation. We examined diet, foraging modes, habitat selection, fish abundance, and factors associated with fish availability. Based on biomass, prey remains yielded 76% fish, 14% mammals, and 10% birds. On rivers, eagles primarily caught live fish as they spawned or foraged in shallow water, whereas, on reservoirs, most fish were obtained as carrion or as they floated moribund on the surface. Fish communities differed among river reaches and reservoirs, and ecological and life-history characteristics influenced vulnerability and seasonal differences in exploitation, Water temperature, a principal factor determining fish community structure among eagle territories, was also associated with temporal differences in fish availability, as was flow and turbidity. Few prey sources remained constant throughout the reproductive cycle, and prey and habitat diversity buffered temporal changes in prey availability. We conclude that dams benefit breeding eagles to the extent that they create water temperature discontinuities and additional aquatic habitats, some that support large populations of fish. However, environments modified by dams are not necessarily better for Bald Eagles than those on free-flowing sections of rivers; our data show that Bald Eagle reproduction in the two settings is nearly identical.

Key Performance Indicators for maintenance of hospital buildings

Abstract: Maintenance management of hospital buildings is one of the more complex issues in the field of maintenance. The performance and operation of hospital buildings are affected by numerous factors. These include hospital occupancy relative to standard occupancy, age of buildings, and building surroundings. The purpose of this research was to quantify the effects of users, building characteristics and systems on the buildings' performance and maintenance. The following factors were investigated: 1. Overall performance of the building: A Building Performance Indicator (BPI), based on systematic performance and maintenance rating scales, was used to monitor the building's performance. 2. Age of the building: A high correlation was found, using a Life Cycle Cost analysis, between maintenance expenditures and the age of a hospital building. 3. Building's level of occupancy: The maintenance labor inputs of two identical hospitalization wards with different occupancy levels were compared over a period of 3 years. The results showed that maintenance labor inputs for the higher occupancy ward (133% of the standard) were 22% higher than for the other ward. 4. Level of labor outsourcing: The financial benefits of outsourcing maintenance activities were investigated through a field survey. Facilities with high occupancy levels and frequent breakdowns were compared with facilities with standard occupancy levels that practice preventive maintenance extensively. It was found that for standard occupancy facilities, outsourcing of maintenance resulted in a saving of 8% of the overall maintenance expenditure. For facilities with high occupancy levels, use of in-house labor resulted in a 6% decrease in maintenance expenditures. The coefficients and diagrams developed were integrated into 4 Key Performance Indicators for Hospital Buildings. The model was examined in 6 Case studies one of which is presented.

Network system, network equipment, exclusive control method and program

Abstract: PROBLEM TO BE SOLVED: To properly remote-control operations of object equipment SOLUTION: An occupancy management processing section 52 records and registers information denoting the release timing of an occupancy right to a release timing registration area 42 Upon the receipt of an occupancy provision request sent from a control unit, the occupancy management processing section 52 discriminates whether or not the section 52 has already provided the occupancy right to other unit When discriminating not providing the occupancy right, the occupancy management processing section 52 stores a node ID and a unique ID of the control device transmitting the occupancy provision request to an occupancy information storage area 41 Furthermore, the occupancy management processing section 52 discriminates whether or not a release timing comes on the basis of a notice signal sent from a timing detection section 51, and carries out the processing to release the occupancy right, when discriminating the timing comes Moreover, when a bus reset takes place after the occupancy management processing section 52 provides the occupancy right to the control unit, the occupancy management processing section 52 updates the storage contents of the occupancy information storage area 41

An analysis of Smith Travel Research occupancy estimates: a case study of Virginia Beach Hotels

Abstract: Smith Travel Research's estimates of lodging occupancy in Virginia Beach have improved over time, most likely because its sampling accuracy has increased.