Voxel-Based Probabilistic Space-Time Prisms for Analysing Animal Movements and Habitat Use

Time-geographic analysis has been limited in the past by its capacity to model only potential locations for moving objects, without sufficiently evaluating which locations are more probable. This paper expands upon existing research in probabilistic time geography by accomplishing two main tasks. First, a new geocomputational approach is presented for generating probabilistic space-time prisms. Here, probabilistic space-time prisms are represented as three-dimensional rasters of volume elements, or voxels, that record the probability that an object was located at any location at any time. After describing the geocomputational approach, its utility is illustrated through a detailed analysis of tracking data collected for a Muscovy duck (Cairina mochata). Specifically, probabilistic space-time prisms are used to map the duck\u27s fine-scale movement patterns over five complete days of global positioning system (GPS)-tracking. Then, the space-time prisms are used in conjunction with a detailed habitat map of the study area in order to quantify the duck\u27s habitat usage over the course of each day. This application highlights the utility of probabilistic space-time prisms for understanding the movements and activities of animals at fine temporal and spatial scales

Habitat Use and Trajectories of Beef Cattle in South Central Oklahoma

Rangelands continue to hold a prominent role in ecological systems and cultural history. Management of rangelands comprises the science and art of sustainably maintaining intensive production from the grasslands and scrubs. The production of beef cattle in the United States, especially in Oklahoma and Texas, is dependent on the sustainable management of rangelands. The first chapter provides additional background on the focus of this study, that is, rangelands and their associated management practices. The second- and third chapters present research toward improved management following two different objectives. Each respective objective evaluates an analysis methodology over a common set of data. These studies aim to examine 19 individual beef cattle in southcentral Oklahoma on 4,499 acres during a predetermined time-activity budget. The data was collected using collars fitted with global positioning system receivers and was analyzed using Esri ArcPro 3.0.2. The time-activity budgets focused on three diurnal periods and one non-diurnal: morning (0700 – 1000), afternoon (1100 – 1400), evening (1500 – 1800) and night (1900 – 2200). The second chapter focuses on the habitat use of the herd as captured in trajectory data collected by GPS collars. The objectives were to determine the general habitat use characteristics of the herd, throughout the day in context with identifying their main water source use. The results of chapter two suggest that during this study period the herd stayed within the herbaceous land that allowing for grazing and preferred a nearby man-made water source. The third chapter focused on an analysis of trajectory characteristics, where average relocation distance and Euclidean distance from the water source were of particular interest. The results of the third chapter found the herd traveled at a consistent distance during the diurnal periods and then decreased their travel by half during the night. The results of both chapters offer information useful in the guidance of livestock producers for rangeland design and grazing practices. In the third chapter I present an extended discussion of the results from earlier chapters as well as avenues for future research using similar datasets