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Webpages tagged with «lemmings»

Published Feb. 6, 2013 5:25 PM

Populations of small rodents, especially lemmings in alpine and arctic environments, show extreme fluctuations in density from year to year and their cyclic dynamics have interested ecologists for nearly a century. Population dynamics of lemmings are, however, difficult to study because densities are often very low and the spatial distribution among different habitats depends highly on season and population density. This limits the usefulness of traditional studies of population dynamics in fixed trapping grids covering a limited area. In this project we look at seasonal and multi-annual patch occupancy dynamics of lemmings and other small rodents over several square kilometers and relate this to habitat characteristics and population density.

 

Published Feb. 6, 2013 3:13 PM

Since 1970 the population fluctuations of small rodents and shrews have been followed by snap-trapping of two 1ha permanent grids at Finse, Hardangervidda, in June/July and August/September. Trapped animals are located to specific trap stations within the grids, and data on their weight and reproductive state are collected. Until the mid 1990s, trapping indicated rather regular fluctuations with quite variable population peaks every 3-4 years. Since the last great peak in 1994, no substantial peak in small rodent populations has been recorded here. A possible explanation for this change in pattern may be related to changes in the climate as mediated through the snow quality in late winter (cf Nature 456: 93-97).

 

Published Feb. 4, 2013 12:31 PM

Since 1970 the population fluctuations of small rodents and shrews have been followed by snap-trapping of two 1ha permanent grids at Finse, Hardangervidda, in June/July and August/September. Trapped animals are located to specific trap stations within the grids, and data on their weight and reproductive state are collected. Until the mid 1990s, trapping indicated rather regular fluctuations with quite variable population peaks every 3-4 years. Since the last great peak in 1994, no substantial peak in small rodent populations has been recorded here. A possible explanation for this change in pattern may be related to changes in the climate as mediated through the snow quality in late winter (cf Nature 456: 93-97 ).

Published Feb. 4, 2013 12:31 PM

Populations of small rodents, especially lemmings in alpine and arctic environments, show extreme fluctuations in density from year to year and their cyclic dynamics have interested ecologists for nearly a century. Population dynamics of lemmings are, however, difficult to study because densities are often very low and the spatial distribution among different habitats depends highly on season and population density. This limits the usefulness of traditional studies of population dynamics in fixed trapping grids covering a limited area. In this project we look at seasonal and multi-annual patch occupancy dynamics of lemmings and other small rodents over several square kilometers and relate this to habitat characteristics and population density.

Published Apr. 20, 2009 12:04 PM

In this project the student will look at patch occupancy rates, habitat choice, species co-occurrence and spatial dynamics of lemmings and other small rodents throughout the summer season (June through September). Patch occupancy may be detected by track tunnels, signs of grazing, fecal pellets, visual observations, detection by the help of a dog and/or live-trapping. The student will learn state-of-the art statistical methods for estimating true occupancy rates in the face of imperfect detection probabilities, and will have the opportunity to attend an international course/workshop on the topic. The student will also have the opportunity to learn about and use geographical information systems (GIS).