Truvé, J. & Lemel, J. 2003: Timing and distance of natal dispersal for wild boar Sus scrofa in Sweden. - Wildl. Biol. 9 (Suppl. 1): 51-57.

In order to estimate age at natal dispersal and dispersal distance, wild boars Sus scrofa were studied in Sweden by use of mark-recapture and telemetry. To describe the average natal dispersal in the population, we applied a sigmoid regression model to analyse the age specific distance to the natal site. We used the first and second order derivatives of the model to determine at which average age dispersal begins, reaches its maximum rate and ceases. The average dispersal distance was estimated by the maximum value of the model. Using this method, we reached the conclusion that male wild boars begin to disperse at the age of 10 months, reach their maximum dispersal rate at the age of 13 months, and that dispersal ceases at the age of 16 months. At that age, they have dispersed 16.6 km from their natal sites. For females, the corresponding ages were 7, 9 and 11 months, with a dispersal distance of 4.5 km. The results follow the prevalent opinion on natal dispersal in polygynous mammals. Dispersal distances are generally short with a negative exponential probability distribution. Dispersal reaches its maximum rate during the age at which sexual maturity is occurring, and males disperse longer distances than females.

Key words: dispersal, dispersal distance, dispersal distance distribution, natal dispersal, sex-biased dispersal, Sus scrofa, wild boar

Johan Truvé, Göteborg University, Department of Applied Environmental Science, P.O. Box 464, SE 405 30 Göteborg, Sweden - E-mail: johan.truve@miljo.gu.se
Jonas Lemel*, Swedish Association for Hunting and Wildlife Management Research Unit, Bäcklösavägen 8, SE 756 51 Uppsala, Sweden - e-mail: jonas.lemel@telia.com

*Present address: Swedish Association for Hunting and Wildlife Management, Öster Malma, 611 91 Nyköping, Sweden