Abstract

Topic: Ungulate species interactions and management

The long-term monitoring of moose on the island of Vega

Erling Johan Solberg¹, Morten Heim¹, Ivar Herfindal², Christer M. Rolandsen¹, Bernt-Erik Sæther²

Norwegian Institute for Nature Research (NINA), Postbox 5685 Torgarden, 7485 Trondheim, Norway
Center for Biodiversity Dynamics, Institute for Biology, and Gjærevoll Centre for Biodiversity Foresight Analyses, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway

Abstract
Long-term individual-based studies of large herbivores are rare and expensive to conduct, but have great benefits regarding the research questions that can be answered. In 1992, we established an individual-based study of the small moose population on Vega in northern Norway and during the next 31 years we followed the individual life histories of almost all moose that were born on or immigrated to the island. We captured, weighed and tracked by the use of VHF and GPS collars, all adults, immigrants and most calves that survived the autumn hunt (~350) and measured and aged all moose that were harvested or died due to other factors (~700). Recently, we also developed a near complete genetic pedigree for the population (for four months and older individuals) – even back to the two moose that first colonized Vega in 1985. In five successive projects, we have used life-history data to examine key aspects of moose ecology and genetics, with emphasis on the impact of recreational hunting on short- and long-term population performance. Focal studies have included the effects of sex- and age-specific harvesting on moose reproduction and body growth, as well as the evolutionary consequences of hunting. Given the isolated location of the island 13 km off the mainland, we also explored how inbreeding, migration and inbreeding avoidance can affect moose demographic performance, and based on the detailed pedigree, we have learned about the drivers of variation in lifetime breeding success of male and female moose. Our field studies at Vega have shown us that long-term, individual-based data, even from a rather small winter population of 24-55 individuals, can provide results of great relevance for moose management and research. However, capture, collaring and re-collaring of moose each year is expensive and practically demanding, and we have now reduced our field activities on the island. The last moose were radio-collared in 2022, and in the future, we will mainly monitor the population by the number, sex and age of moose that are seen and killed during the hunting season, and by regular analyses of kinship patterns.