Doctoral Dissertation Research: Using GPS to Track Vultures in Texas

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Vultures are catalysts of the decomposition process, but their scavenging is underreported in the academic literature. Moreover, forensic scientists have realized that some vultures will feed on human cadavers in addition to road-kill, thereby complicating time-since-death estimations. Research from Texas State University's Forensic Anthropology Research Facility (FARF) has shown that vultures arrive early during the decomposition process and leave few clues to indicate their prior scavenging presence. As a result, one option to aid law-enforcement during medical-legal investigations involving unidentified human remains will be to identify vultures' preferred and most likely scavenging environments. This doctoral dissertation research project will use global positioning system (GPS)-based satellite telemetry to track vultures in order to analyze and compare the spatial distribution of vulture scavenging behavior at FARF versus vulture scavenging behavior at other non-forensic locations and to establish a predictability model of likely vulture scavenging habitats using remote sensing techniques and spatial and temporal statistics. The doctoral student will attach 45-gram GPS transmitters to vultures. These transmitters will record the vultures' locations every hour for six months. The vulture locational data will be entered into a geographic information system (GIS) to isolate probable vulture scavenging locations using spatial analytic methods, including descriptive statistics, rigorous statistics for hotspot analysis, kernel density estimations, and time-space analysis. A predictability model of vulture scavenging locations will be created using a range of variables, including land cover, distance to roads, and climate data obtained from nearby weather stations. The student will test the hypothesis that land elevation and distance to water will have the greatest impact and that FARF is a vulture scavenging hotspot regardless of the underlying geography. Data from locations where vultures are observed scavenging in the wild will be used to validate the model.This research project differs from other vulture scavenging studies in that the vultures in question are feeding on human cadavers rather than road kill. No other study has ever investigated the spatial distribution of vultures that are known to scavenge on human cadavers. Moreover, GPS wildlife tags combined with GIS technologies have enhanced the scope at which animals can be studied. One remaining challenge is identifying a method that will allow researchers to obtain discrete point data with a continuous observational history for a specific animal behavior such as scavenging. Vultures are excellent research subjects for testing, because they are soarers rather than fliers and they spend the majority of their day in the air. Combining this behavior with the ability to obtain hourly locational data from the GPS transmitters, will allow for the opportunity to discern geographic data linked to specific vulture activities. This project will generate fundamental advances of scientific knowledge by using GPS and GIS to provide an enhanced understanding of vulture scavenging. Furthermore, the results will identify the geographic features associated with probable vulture scavenging locations, thereby contributing to forensic investigation efficiency and accuracy, aviation safety, and vulture conservation. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.