Hunting effort and game vulnerability studies on a small scale: a new technique combining radio-telemetry, GPS and GIS

1. Global positioning systems (GPS) were used to track hunters in an area of central Norway where willow ptarmigan Lagopus lagopus were contemporaneously radio-tracked. A geographical information system (GIS) was then used to study spatiotemporal interactions between hunters and game. 2. Recording hunting activity with the GPS produced accurate and unbiased information about the behaviour and effort of hunters. When GPS tracking nine hunters during 50 hunter-days, data were lost for an estimated time of 30 h 45 min, which constituted about 10% of the total hunting time. 3. Willow ptarmigan hunters walked on average 16.2 km daily at a speed of 2.8 km h(-1), and they hunted for 9 h each day, of which almost 6 h was active hunting time. During 50 hunter-days they had 295 h of active hunting, covered a distance of 818 km and harvested 20% of the willow ptarmigan population in the area. 4. The spatial distribution of hunting pressure was strongly dependent on the starting point of the hunters, and areas close to the base cabin were subject to most hunting activity. Areas furthest away, towards the border of the hunting area, experienced little hunting activity. 5. Logistic regression showed that survival probability of ptarmigan was best predicted by distance from the cabin. Shot radio-tagged birds lived closer to the cabin, and had twice as high hunting pressure in their home range, compared with surviving radio-tagged birds. 6. This method of obtaining quantitative data about human effort will have application in other studies when there is a need to quantify and analyse human effort on temporal and spatial scales.