This PHD project is part of the project ‘Extinction mechanisms in small populations’. The main objective is to improve our understanding of the immigration process and how settlement of new individuals affects population performance. The root vole (Microtus oeconomus) and the bank vole (Myodes glareolus) are used as model species due to their contrasting social system and their well-known biology. I will use a combination of previously collected experimental data and data from an ongoing monitoring of natural populations. In the experimental part determinants of settlement, reproductive success and the consequences for population demography will be investigated. In the observational study immigration and colonisation on 15 islands in the river Glomma will be monitored for 3 years. Here I will explore the relative contribution of various habitat and social components on the colonisation/immigration success and population performance. This combination of approaches will enable a comparison of results between a controlled experimental system and a system containing natural stochastic factors.
Left: One of the islands in the Glomma river, close to Koppang, that is surveyed for immigration of voles. Right: top: Microtus oeconomus, bottom: Myodes glareolus. Photo: Petter Glorvigen