Epsilon Archive for Student Projects

Abstract

Intraspecific differences in movement over time occur across many taxa. In moose (alces alces), such behaviour has been seen during the rut. Knowledge about behavioural patterns can improve management since it can act as a tool in decision-making. Sweden’s moose population has a skewed sex ratio to the benefit of females as a result of the current hunting system. Skewed sex ratio can have negative impact on populations since it can cause breeding with individuals that otherwise would not have been selected for. Therefore, I tested for differences between male and female moose in movement speed and the impacts of age and the time of day. I also tested the size of the home range and the intrasexual differences in male movement speed depending on observed proportion of male moose. The data came from GPS-marked adult moose in Sweden. The study areas reached from Norrbotten county in northern Sweden to Kronoberg county in the south. Due to geographical and climatic differences across Sweden, I divided the study into a northern and southern area. I used a linear mixed model for the analyses, except when testing the movement speed across the day. Here I used a generalized additive mixed model to account for non-linear movement. I analysed data of 622 individuals (females=464, males=184). Male movement speed was always higher than for females, except for moose above the age of 13 in northern Sweden. The movement speed over the day showed a bimodal distribution for both northern and southern areas, with the peaks matching timing of dawn and dusk. The pattern of the changes in movement speed shared high similarities between sexes, but females had a constantly lower movement speed than the males. Predicted movement speed of males in southern Sweden compared to the observed proportion of male moose, to my surprise, showed a decrease with increasing male proportion. In northern Sweden, I found no relationship between male moose movement and proportion of males in the area. Home ranges were at both 50 and 95% estimate larger for male moose than for female moose in both northern and southern areas. The higher movement rate and home ranges of male moose could reduce the effect of negative impacts of a skewed sex ratio. Prime aged male moose move more than not primed age males and for that reason may increase their chances to breed with several females. Future studies of rutting behaviour may benefit from comparing the differences between rutting season and other season to unravel what in these intraspecific differences that is induced by the rut.