Showing papers on "Occupancy published in 2004"

Factors influencing occupancy of nest cavities in recently burned forests

Abstract: Recently burned forests in western North America provide nesting habitat for many species of cavity-nesting birds. However, little is understood about the time frame and the variables affecting occupancy of postfire habitats by these birds. We studied factors influencing the occupancy and reuse of nest cavities from 1–7 years after fire in two burned sites of western Idaho during 1994–1999. Tree cavities were used for nesting by 12 species of cavity nesters that were classified by the original occupant (strong excavator, weak excavator, or nonexcavator) of 385 nest cavities. We used logistic regression to model cavity occupancy by strong excavators (n = 575 trials) and weak excavators (n = 206 trials). Year after fire had the greatest influence on occupancy of nest cavities for both groups, while site of the burn was secondarily important in predicting occupancy by strong excavators and less important for weak excavators. Predicted probability of cavity occupancy was highest during the early year...

Associations between forest fire and Mexican spotted owls

Abstract: In 1993, the US Fish and Wildlife Service listed the Mexican spotted owl (Strix occidentalis lucida) as threatened, in part because of the rising threat to its habitat from stand-replacing wildfires. In 1997, we surveyed 33 owl sites that, in the previous four years, had burned at various levels ranging from light controlled burns to stand-replacing fires. We compared owl occupancy and reproduction in these burned sites to 31 unburned owl sites with similar habitat and topography. Although unburned sites showed higher proportions of both occupancy and reproduction, the negative relationship observed between recent fire occurrence and owl occupancy rank was statistically weak (Test for Marginal Homogeneity, P = 0.110). Owls tended not to be present where pure pine stands (Pinus spp.) comprised a large proportion (38-85%) of burned sites, but no other factors relating to habitat or fire severity had a significant, biologically interpretable influence on occupancy rank. We suspect that relatively low-intensity ground fires, including most prescribed fires, probably have little or no short-term impact on Mexican spotted owl presence or reproduction, but we have no data on long-term effects of fire. We recommend proactive fuels-management treatments in areas not currently occupied by owls as a means of reducing fire risk in areas occupied by owls. Within areas occupied by owls, judicious treatments may be appropriate after case-by-case evaluations of potential benefits and risks within those sites.

Initially testing an improved extrapolative hotel room occupancy rate forecasting technique

Abstract: SUMMARY The existing time series forecasting models either capture the informationof the last few data in the data series or the entire data series is used for projecting future values. In other words, the time series forecasting models are unable to take advantage of the last trend in the data series, which always have a direct influence on the estimated values. This paper proposes an improved extrapolative time series forecasting technique to compute future hotel occupancy rates. The performance of this new technique was tested with officially published room occupancy rates in Hong Kong. Forecasted room occupancy rates were compared with actual room occupancy rates in several accuracy performance dimensions. Empirical results indicate that the new technique is promising with reasonably good forecasting results.

Habitat features affecting beaver occupancy along roadsides in new york state

Abstract: Characterizing habitat features that influence beaver (Castor canadensis) occupancy along roadsides may have important implications for managing damage to roads caused by beaver activity. We initiated this study to develop proactive and long-term approaches to deal with nuisance beaver along roadsides. From June to October 1997 and 1998, we sampled 316 roadside sites in New York state, USA—216 sites where beaver occupied the roadside area and 100 unoccupied sites. We used stepwise logistic regression to identify habitat variables associated with beaver occupancy along roadsides. We evaluated regression models through measures of sensitivity and specificity. The logistic function retained the percentage of roadside area devoid of woody vegetation, stream gradient, the interaction between these 2 variables, and stream width in the final model. Precluding beaver occupancy along highways would necessarily involve large-scale removal of woody vegetation that would be impractical in all but the most in...

Estimating the abundances of large herbivores in the Kruger National Park using presence–absence data

Abstract: Conservation planning and practice rely heavily on abundance information generated at local scales for decision-making. Unfortunately most distributional data are only provided as presence–absence records at regional or national scales and cannot be used for making local conservation decisions. To date, two methods have been proposed for estimating local abundances and area of occupancy from coarse-scale presence–absence data. Kunin (1998) proposed the use of the fractal method, which assumes that species distributions are self-similar across scales. He & Gaston (2000a), in turn, proposed the use of the negative binomial distribution (NBD) for estimating abundances from presence–absence data collected at different scales. Previously only plant data were used to test these models. In the present study, they were tested using distributional presence–absence, as well as abundance data for a selection of large herbivores that have a restricted distribution in the Kruger National Park, South Africa. The results illustrate that the fractal method tends to overestimate areas of occupancy, while the NBD method underestimates the areas of occupancy of all species. This means that there were significant differences between the predictions provided by the two methods. Both these methods rely on the relationship between the area of occupancy and the size of the area over which the survey is conducted, but describe this relationship in a different way. These techniques could prove useful in the field of conservation biology and this study illustrates that these methods can be used on large mammal species and deliver results that are consistent with previous studies on plants.

Factors affecting bat house occupancy in colorado

Abstract: Artificial roosts known as bat houses have been developed to replace natural roosts that are destroyed and to create new roosts where they are lacking. I investigated the effects of variables related to bat house characteristics and ecological conditions on patterns of roost oc- cupancy in 95 bat houses. Bat houses seem to have been used exclusively as day roosts, with an overall occupancy rate of 11.6%. The presence of bats roosting in the immediate area prior to the placement of the house was an important predictor of occupancy. When bats were already present at a site, the occupancy rate increased to 63.6%. Likelihood of occupancy also was in- creased by providing houses with larger landing areas, by mounting them on buildings instead of trees, and by placing houses in areas with low canopy cover and low levels of human disturbance. Bat houses are probably best used when a roost is going to be destroyed, or a colony excluded, and when the houses can be placed in the immediate area of the old roost.

Abundance – occupancy relationships in macrofauna on exposed sandy beaches: patterns and mechanisms

Abstract: We studied the relationship between abundance and extent of occupancy of 158 species of macrofauna inhabiting 66 sandy beaches around the coast of Great Britain. We also used these data to test the predictions of two hypotheses proposed to explain positive abundance-occupancy relationships. We found a strong positive relationship between abundance and extent of occupancy; this pattern was apparent in taxonomic subsets of organisms which have contrasting reproductive and dispersal traits such as planktotrophic/lecithotrophic development in the plankton vs brood development under parental care. Moreover, the abundance-occupancy relationships in these taxonomic subsets had statistically indistinguishable slopes, and elevation. We propose that this lends support to the notion that differences in population structure such as the tendency to form metapopulations may not be primary determinants of the abundance-occupancy pattern in these taxa as proposed by the rescue/metapopulation hypothesis. To test the predictions of the niche-breadth hypothesis we derived values describing the range of sediment grain-sizes exploited by members of two taxonomic subgroups: amphipods and bivalves. We found a weak, statistically non-significant relationship between this niche-breadth measure and occupancy in bivalves which have been shown to respond to grain-size in previous studies, however this was negated after correction for possible artefacts of sampling effort. All other relationships between abundance or occupancy and grain-size range were non-significant. The consistency of the demonstrated abundance-occupancy relationship with those demonstrated in other studies of primarily terrestrial fauna indicates some shared mechanistic explanation, but our data fail to provide support for the two mechanistic hypotheses investigated.

An examination of factors affecting high occupancy/toll lane demand

Abstract: An Examination of Factors Affecting High Occupancy/Toll Lane Demand. (August 2004) Justice Appiah, B.Sc. (Hons), Kwame Nkrumah University of Science and Technology Chair of Advisory Committee: Dr. Mark W. Burris In recent years, high occupancy/toll (HOT) lanes have gained increasing recognition as a potential method of managing traffic congestion. HOT lanes combine pricing and vehicle occupancy restrictions to optimize the demand for high occupancy vehicle (HOV) lanes. Besides having all the advantages of traditional HOV lanes, HOT lanes can also generate revenue to help finance various operation and maintenance programs. At present there are four fairly well established HOT lane projects in the United States: two in Houston, Texas, and one each in San Diego, and Riverside County, California. After 6 years in operation, Houston’s HOT lanes receive comparatively lower patronage than the two California projects. An understanding of why people choose to use HOT lanes will be vital to improving the performance of existing HOT facilities and will also shed light on policy decisions regarding future HOT lane investments. This study examined the relative importance of different parameters which could be expected to influence the demand for HOT lanes using standard statistical and discrete choice modeling techniques on survey data from Houston’s HOT lane users. iv The study showed that, controlling for other variables, trip length, the driver’s perception of travel time savings offered by the HOT lanes, frequency of travel in the freeway corridor, trip purpose, and the amount of time spent on carpool formation were good predictors of HOT lane usage. Socioeconomic characteristics such as age and level of education were also good indicators of the frequency of HOT lane usage whereas household size, occupation, and hourly wage rate were not. Gender and annual household income were only loosely related to HOT lane usage. Inelastic responses to minor changes in the toll coupled by responses to a question regarding participants feeling towards the $2.00 toll, suggested that the toll was not a major deterrent to HOT lane usage. A primary deterrent was the need for one passenger to use the HOT lane when free use required two passengers. However, travelers who shared the toll with their carpool partners were likely to have made more frequent HOT lane trips than those who bore the entire cost. v DEDICATION To the memory of my teacher and mentor Ms. Faustina Mensah

Converging redundant sensor network information for improved building control

Abstract: Knowing how many people occupy a building, and where they are located, is a key component of building energy management and security. Commercial, industrial and residential buildings often incorporate systems used to determine occupancy, however, current sensor technology and control algorithms limit the effectiveness of both energy management and security systems. This topical report describes results from the first phase of a project to design, implement, validate, and prototype new technologies to monitor occupancy, control indoor environment services, and promote security in buildings. Phase I of the project focused on instrumentation and data collection. In this project phase a new occupancy detection system was developed, commissioned and installed in a sample of private offices and open-plan office workstations. Data acquisition systems were developed and deployed to collect data on space occupancy profiles. Analysis tools based on Bayesian probability theory were applied to the occupancy data generated by the sensor network. The inference of primary importance is a probability distribution over the number of occupants and their locations in a building, given past and present sensor measurements. Inferences were computed for occupancy and its temporal persistence in individual offices as well as the persistence of sensor status. The raw sensor data were also used to calibrate the sensor belief network, including the occupancy transition matrix used in the Markov model, sensor sensitivity, and sensor failure models. This study shows that the belief network framework can be applied to the analysis of data streams from sensor networks, offering significant benefits to building operation compared to current practice.

Measurement and statistical analysis of spectrum occupancy

Abstract: In this paper, we discuss two definitions of spectrum occupancy in land-mobile radiocommunication, actual occupancy and mean occupancy. We argue that for most monitoring purposes, the mean occupancy is the more relevant notion. We propose measurement procedures for spectrum occupancy, based on discrete observations of the channel, and investigate their properties. For the estimation of the mean occupancy, we provide confidence intervals, both for long as well as for short sampling intervals. For short sampling intervals, dependence of the observations is of crucial importance. We analyse the dependence for an alternating renewal model with Erlang(2)-distributed renewals, which is better supported by the data than the exponential distribution used in past models. For the estimation of the actual spectrum occupancy, we propose a new random sampling scheme and investigate its properties. Copyright © 2004 AEI.

Sources of Variance in Employee Perceptions of Occupancy Quality

Abstract: This study addresses the goal of an integrative approach to evaluating the effects on work of environmental design. Results are based on pre-occupancy evaluations of 2 different office workplaces, with many parallels in occupancy design. Methods entailed: (1) measurement of noise, lighting, and thermal conditions at selected work stations; and (2) administration of an occupancy quality perceptual response survey questionnaire. A 2-step, least-squares (2SLS) multiple regression method was used for sources of variance analysis of responses to occupancy quality items on the questionnaire. The major result is that observed variance in major indicators of occupancy quality is not explained by responses to the same questionnaire items for the 2 sites. The findings support the conclusion that, across different occupancy design settings, observed variability in work behavior is not likely attributable to a universal set of design factors.

Energy conservation electrical circuitry for lighting control by occupancy sensors, in building's large spaces

Abstract: 1. Maximum energy conservation is achieved with “occupancy sensor” lighting control. The circuitry of this invention extends occupancy sensing coverage as required for “large space” light control. Occupancy sensors currently sense up to 2000 square feet. Lighting Control Timer Panels are currently used to control lights in large space within a building.

Living in the Forest: Meanings and Use of Recreational Residences

Abstract: The Forest Service Recreation Residence Program has been operational since the passage of the Occupancy permits Act in 1915. In the initial years the Forest Service actively encouraged summer home occupancy with the view that such occupancy encouraged recreational use and assisted in proper forest management and fire control as well as providing a source of income. Approval of further recreation residence development on public land was discontinued in 1968 as program costs exceeded revenues and the perception that such occupation of public land was elitist and potentially restricted public access to desirable recreation sites. More recently, both the appraisal process and the pursuance of permit violations have become a focus of some political controversy. Recreational residences have often been built by and remain in the same family across generations leading to a strong attachment and identification with a particular forest tract. The study discussed in this paper examines the use of these residences and the meanings of such use to a sample of cottage owners in the Arapahoe-Roosevelt and Pike National Forests in Colorado, USA. A multi-methods approach was used to collect data on cottage use including project analysis, surveys, experiential sampling and in-depth interviews. The rationale underlying the multi-method approach and some preliminary results of this study will be presented in this paper.