An application of the bait-marking method for the study of spatial activity of wild boar in southern Sweden

Sammanfattning: In this study, the bait-marking method is for the first time tested on wild boar as a means to document movements. The results of the bait-marking study are compared to the results of a GPS surveillance study conducted in the same area. The mode of surveying animal movements by the use of tracking device such as GPS-transmitters is a well-established method which provides detailed data to many wildlife research-projects. Currently, some wild boars in the southern and middle parts of Sweden are the subjects of a GPS-study performed by researchers at the Department of Animal Ecology at the SLU in Umeå. The use of GPS-transmitters is a method that has some limitations, like high costs and that advanced equipment is demanded. The bait-marking method may offer a cheap and uncomplicated technique for indirect surveillance of spatial activities of wild boar. Indigestible markers are placed in bait, and findings of markers in faecal droppings provide information of the spatial activity of the animal in question. During April-May and September-October in 2006, bait containing plastic markers was placed on wild boar feeding sites on the Högestad estate in Skåne, southern Sweden. Estimations of home range size, position and overlap were made from the GPS-coordinates provided by the wild boar project at the SLU to compare with the results given from the bait-marking study and as a means to evaluate seasonal effects on the method. The method of delivery of the markers to wild boars proved usable during both seasons of the study as both bait and markers were consumed by boars at all observed occasions of pigs visiting feeding sites. Some feeding sites were during the study visited by wild boars originating from different home ranges. No markers were found at any of the fields that were searched during the study. There was a significant difference in the rate of recovered markers in faecal piles at feeding sites between spring and autumn. Altered ranging behaviour in terms of variance in autumn and spring home range sizes were found to be significant. An extended study is suggested for further analyses and development of the bait-marking method. Furthermore, some modifications of the method are suggested.