A note on using a laser-based technique for recording of behaviour and location of free-ranging animals

We developed a precise, remote (up to 300 m) observation system to record animal location and behaviour that requires no animal handling or disruption of the normal environment. Our system, combining a survey laser and a laptop, also allows recording of observed animal behaviour from seconds to hours, with accuracy of 1 m or better. Up to one individual per second can be located, which supports data collection of large numbers of animals not possible with other methods. The laser system was used to track a halter-broken heifer led in an arc beginning and ending about 50 m from the laser with a maximum distance of about 150 m. We recorded the location of the heifer at 35 points along the arc using the laser, a global positioning system (GPS), and a nylon tape. There was an average linear difference of 1.16 m (S.D. 0.63) between the laser data and the GPS data. The laser was potentially more accurate than GPS for this application because the laser averaged only 0.21 m (S.D. 0.24) linear difference from the tape. Tests of the laser to relocate points in the field to within 0.20 m and 0.1°, averaged 0.42 m (S.D. 0.29) from the original points. Our technique allows precise location of behaviour and navigation to grazed sites, potentially revealing how animals interact with the resources they exploit and showing the effect of landscape spatial heterogeneity on foraging and habitat use patterns.