Íslenska hagamúsin Apodemus sylvaticus: Stofnbreytingar og takmarkandi þættir á norðurmörkum útbreiðslu

• Main Author: Ester Rut Unnsteinsdóttir 1968-
• Other Authors: Háskóli Íslands
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2014
• Subjects: Líffræði; Doktorsritgerðir; Iceland
• Online Access: http://hdl.handle.net/1946/18345

The wood mouse is a suitable model species for studying potential limiting factors and population ecology at the edge of the distribution range. The species arrived in Iceland with the settlers before or during the 10th century but Iceland is north of the natural range of the species. No other rodent is found so widely in the wild. The aim of this research was to uncover the forces that act on population dynamics of the Icelandic wood mouse population. For this purpose Capture-Mark-Recapture surveys were conducted in two contrasting habitats: grassland and woodland, both located in southwest Iceland. This study revealed strong evidence of density-independent control of the wood mouse population in the grassland. At the woodland site, however, density-dependent factors were believed to act on the population as is the case near the centre of the species´ European range. According to this comparative study the woodland is a far better habitat for wood mice than the grassland. Population density was manifold higher, monthly survival rate was stable and did not fluctuate with temperature, body mass was higher and food was most likely of a better quality. All these factors are important for sustaining a viable population. During spring and early summer, low trappability resulted in small sample sizes and problems with population estimates and other statistical analyses. In the autumn, all generations were easily trapped and sample sizes were sufficient for age- and habitat-specific analysis. As the population estimates rely on trap data, which is difficult to obtain during periods of low trappability, a novel method was developed to address this problem. It made it possible to detect summer recruitment 100 days earlier than traditional population estimates could. This study shows that live-trapping data obtained during periods of peak density can be a useful aid when describing population parameters of the previous months when sample sizes are too low for direct measurements. This is important for ethical reasons and ...