Inference of Animal Activity From GPS Collar Data on Free-Ranging Cattle

Abstract

Global positioning systems (GPSs) enable continuous and automatic tracking of an animal's position. The value of such spatialtemporal information can be improved if the corresponding activity of the animal is known. We evaluated the potential of Lotek GPS collars to predict activity of beef cattle on extensive rangeland in 2 contrasting foraging environments. Collars were configured to record animal location at intervals of 20 minutes (United States) or 5 minutes (Israel), together with counts from 2 motion sensors. Synchronized field observations of collared cows were conducted in 1999 (United States) and in 2002 and 2003 (Israel). Grazing, traveling (without grazing), and resting activities were recorded as minutes out of 20 for each category (United States), or as a single category (Israel). For the US data, stepwise regression models of grazing, traveling, and resting time accounted for 74%-84% of the variation, on the basis of the motion sensor counts for the left-right axis and the distances between GPS fixes. Regression tree analysis of grazing time yielded a simple model (4 splits) that accounted for 85% of the variation. For the Israeli data, the misclassification rates obtained by discriminant analysis and classification tree analysis of animal activity were 14% and 12%, respectively. In both analyses, almost all grazing observations were correctly classified, but other activities were sometimes misclassified as grazing. Distance alone is a poor indicator of animal activity, but grazing, traveling, and resting activities of free-ranging cattle can be inferred with reasonable accuracy from data provided by Lotek GPS collars. Resumen Los sistemas de posicionamiento global (GPS) permiten el rastreo continuo y automá tico de la posició n de un animal. El valor de tal informació n espacial-temporal pueden ser mejorado si la actividad correspondiente del animal es conocida. Evaluamos el potencial de los collares de GPS Lotek para predecir la actividad del ganado para carne en un pastizal extensivo en dos ambientes de forrajeo contrastantes. Los collares fueron configurados para registrar la ubicació n del animal a intervalos de 20 min (US) o 5 min (Israel), junto con conteos de dos sensores de movimiento. En 1999 (US), 2001 y 2002 (Israel) se condujeron observaciones de campo sincronizadas de las vacas con collar. Se registraron actividades de apacentamiento, viaje (sin apacentamiento) y descanso en términos de minutos dedicados a cada actividad dentro del período de 20 minutos (US) o como una sola categoría (Israel). Para los datos de US, los modelos de regresió n a pasos para apacentamiento, viaje y tiempo de descanso explicaron de 74-84% de la variació n, basados en los conteos del sensor de movimiento para los ejes derecho-izquierdo y las distancias entre las determinaciones del GPS. El aná lisis de regresió n de á rbol del tiempo de apacentamiento produjo un modelo simple (cuatro divisiones) que explicaron el 85% de la variació n. Para los datos de Israel, las tasas de clasificació n erró nea obtenidas p...

Precision livestock production: tools and concepts

“…On the other hand, long distances between successive records indicate directional movement not related to grazing. Although Ungar et al (2005) concluded that distance alone is a poor predictor of cattle activity, Putfarken et al (2008) classified activities as grazing if distances between fixes at 5-minute intervals were between 6 and 100 m, and obtained 94.3 and 89.4 correct classification rates for cattle and sheep.…”

“…Buerkert & Schlecht (2009) found significant differences in accuracy and precision among different units, particularly in rugged terrain. Ungar et al (2005) found that most grazing activity could be identified with models developed, but frequently other activities were classified as grazing. Overall misclassification rates were 12-14% for all activities.…”

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“…The study of landscape use by animals requires a record of the location of individuals over time (Ungar et al 2005). Technical and logistic difficulties in obtaining and collating such data have hampered the study of free-ranging animals in a spatially explicit way (Coughenour 1991).…”

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