Rangeland Ecol Manage 59:334–340 | May 2006 Technical Note An Advanced, Low-Cost, GPS-Based Animal Tracking System Patrick E. Clark,1 Douglas E. Johnson,2 Mark A. Kniep,3 Phillip Jermann,4 Brad Huttash,3 Andrew Wood,5 Michael Johnson,6 Craig McGillivan,7 and Kevin Titus8 Authors are 1Range Scientist and 4Biological Science Technician, US Department of Agriculture–Agricultural Research Service, Boise, ID 83712; 2Professor and 6Software Programmer, Department of Rangeland Ecology and Management, Oregon State University, Corvallis, OR 97331; 3Electrical Engineers, Micron Technology, Inc, Boise, ID 83716; 5Electrical Engineer, Hewlett-Packard Company, Boise, ID 83714; and 7current and 8former electrical engineering students, Boise State University, Boise, ID 83725. Abstract An improved global positioning system (GPS)–based animal tracking system is needed to meet quickly evolving demands of ecological research, range livestock production, and natural resource management. Commercially available tracking systems lack the data storage capacity needed to frequently collect animal location data (e.g., 15-minute intervals or less) over long-term deployment periods (e.g., 1 year or more). Some commercial systems have remote data–download capabilities, reducing the need to recapture tagged animals for data retrieval, but these systems download data via satellite (Argos), global system for mobile communications (GSM) cellular telephone, or telemetry radio frequencies. Satellite systems are excessively expensive, and GSM cellular coverage is extremely limited within the United States. Radio-based systems use narrow-band very-high– or ultra-high frequencies requiring the user to obtain frequency allocations. None of these existing systems were designed to provide continual, real-time data access. The Clark GPS Animal Tracking System (Clark ATS) was developed to meet the evolving demands of animal ethologists, ecologists, natural resource managers, and livestock producers. The Clark ATS uses memory-card technology for expandable data storage from 16 megabytes to 8 gigabytes. Remote data downloading and program uploading is accomplished using spread-spectrum radio transceivers, which do not require narrow-band radio frequency allocations. These radios also transmit, at a user-defined time interval, a real-time, GPS-location beacon to any Clark ATS base station within range (about 24 km or 15 miles line of sight). Advances incorporated into the Clark ATS make it possible to evaluate animal behavior at very fine spatial- and temporal-resolution over long periods of time. The real-time monitoring provided by this system enables researchers to accurately examine animal distribution and activity responses to acute, short-term disturbances relative to longer- term behavioral patterns. The Clark ATS also provides a huge time- and cost-savings to researchers and natural resource managers attempting to relocate a tagged animal in the field for direct observation or other operations. Resumen Se necesita un sistema mejorado de rastreo de animales basado en GPS para satisfacer las crecientes demandas de investigacio´n ecolo´ gica, produccio´ n de ganado en pastizales y el manejo de los recursos naturales. Los sistemas de rastreo comerciales disponibles carecen de la capacidad de almacenaje de datos necesaria para colectar frecuentemente la localizacio´ n del animal (por ejemplo, a intervalos de 15 minutos o menos) en un perı´odo largo de tiempo (un an˜ o o mas). Algunos sistemas comerciales tienen capacidad de descargar datos a larga distancia, reduciendo la necesidad de recapturar los animales marcados para recuperar los datos, pero estos sistemas descargan los datos vı´a sate´lite (Argos), a trave´s de telefonı´a celular GSM o de radiofrecuencias de telemetrı´a. Los sistemas de sate´lite son excesivamente caros y la cobertura de la telefonı´a celular GSM es extremadamente limitada dentro de Estados Unidos de Ame´rica. Los sistemas basados en radio usan bandas estrechas de frecuencia VHF o UHF, requiriendo que el usuario obtenga asignaciones de frecuencia. Ninguno de los sistemas existentes fueron disen˜ ados para proveer un acceso continuo en tiempo real. El Sistema de Rastreo de Animales Clark GPS (Clark ATS) fue desarrollado para satisfacer las demandas de los eto´ logos animal, eco´ logos, manejadores de recursos naturales y productores de ganado. El Clark ATS utiliza tecnologı´a de tarjeta de memoria para expandir la capacidad de almacenaje de datos de 16 megabytes a 8 gigabytes. La descarga remota de datos y la carga del programa se logra usando radio transcriptores de espectro amplio, que no requieren la asignacio´n de frecuencias de radio de banda angosta. Estos radios tambie´n transmiten, a un intervalo de tiempo definido por el usuario, en tiempo real, la localizacio´ n de la baliza de GPS a cualquier base de Clark ATS dentro del rango ( aproximadamente 24 km o 15 millas en lı´nea recta). Los avances incorporados al Clark ATS hacen posible evaluar el comportamiento animal a una resolucio´ n espacial y temporal muy fina por largos perı´odos de tiempo. El monitoreo en tiempo real suministrado por este sistema permite a los investigadores examinar acertadamente la distribucio´ n de los animales y las actividades en respuesta a disturbios severos a corto plazo en relacio´ n a los patrones de comportamiento a largo plazo. El Clark ATS tambie´n proporciona grandes ahorros de tiempo y costos a los investigadores y manejadores de recursos naturales que intentan relocalizar en el campo a los animales marcados para realizar observaciones directas u otras operaciones. Key Words: activity budgets, animal behavior, global positioning system, habitat use, real-time, telemetry tracking This research was funded by the US Department of Agriculture–Agricultural Research Service. Mention of manufacturer, trademark name, or proprietary product does not constitute endorsement by the US Department of Agriculture, Oregon State University, or Boise State University and does not imply their approval to the exclusion of other products that may also be suitable. Correspondence: Patrick E. Clark, Northwest Watershed Research Center, USDA–ARS, 800 Park Boulevard, Suite 105, Boise, ID 83712-7716. Email: [email protected] Manuscript received 26 September 2005; manuscript accepted 12 March 2006. 334 RANGELAND ECOLOGY & MANAGEMENT 59(3) May 2006 INTRODUCTION spectrum radio to a hand-held base station capable of receiving and displaying collar locations on a digital map; 4) collar units Study of animal ecology using telemetry tracking systems began having a large (up to 8 gigabyte), user-expandable, on-board in the late 1950s and early 1960s (Le Munyan et al. 1959; data storage capacity; and 5) collar components having very Eliassen 1960; Marshall et al. 1962; Cochran and Lord 1963; low power demand (mean consumption , 100 mW) and Mech et al. 1965) using collars or tags emitting very-high fre- batteries with very high capacity (19 AH D-cells). The relatively quency (VHF) radio-signal pulses. Intensive monitoring of widely low cost of the Clark GPS Animal Tracking System (Clark roaming animals with VHF systems, however, was costly, time- ATS) would help the user to economically deploy the system on consuming, and often posed risks to personnel safety. With the an adequate sample size of animals, which may not have been launch of the Nimbus 3 satellite (Kenward 1987) and, later, the possible using a more expensive, commercial tracking system. Argos system (Fancy et al. 1988), it became possible to auto- The capabilities of the Clark ATS would also allow the user to matically collect and transmit location data from widely roaming deploy the system for up to 3 weeks at a data-capture rate of once or migrating animals (e.g., polar bear and caribou) using sat- every minute without the need to recollect and service the collar. ellite communication technology (for examples, see White and For longer-term deployments, the user could configure the Garrott 1990). The positional accuracy of these location data, system to acquire data at 15-minute intervals for up to 1 year however, was quite coarse (6 300 m) (Britten et al. 1999), thus without service. negating their use for habitat-selection studies. Deployment of the NAVSTAR (Navigation Geographic Positioning System [GPS]), declared fully operational in 1995, enabled develop- MATERIALS AND METHODS ment of animal tracking systems with unprecedented positional Clark GPS Animal Tracking System accuracy (6 5 m) (e.g., Rodgers et al. 1996). These GPS-based The Clark ATS consists of a GPS tracking collar (Fig. 1) and tracking systems allowed evaluation of animal movement and a hand-held, mobile base station (Fig. 2). The tracking collar habitat selection at very fine spatial resolution. collects and stores GPS-fix information including collar loca- Despite these technological advances, however, telemetry tion (latitude and longitude), date and time (Greenwich mean), tracking systems have not kept pace with the evolving demands and parameters indicating fix quality (e.g., dilution of precision of ecological research. Costs of commercial GPS tracking and number satellites used) on a removable memory card collars severely limit the sample size (i.e., individual animals) (CompactFlash) contained within the collar. Raw satellite data and statistical power that researchers have available for animal (e.g., carrier phase, pseudorange, and Doppler measurements) ethology and ecology studies. Commercial GPS collars also have acquired and used by the