Finding and establishing new subpopulations

When a subpopulation of animals goes extinct, then residual individuals disperse in search of new habitat patches to start new subpopulations. I plan to study three steps of this process - searching, discovering habitat patches, and establishing subpopulations in those habitat patches. I propose to find out which types of movement patterns are most successful for finding habitat patches, how this success depends on the distribution of habitat patches, which movement patterns do small mammals actually use when travelling in unknown habitats, and how the type of movement pattern used depends on habitat type. I will also measure how perceptual range (from how far away they can detect the habitat patches) varies with habitat and distance from home range for small mammals in experimentally manipulated habitats. The field experiments will be carried out using small mammals (voles and mice). These animals are cheap and easy to work with, allowing us to get large sample sizes quite quickly. The animals would be tracked using a combination of radio-telemetry and thread-spooling. Movement paths would be analysed using a newly-developed statistical technique that differentiates between random and directed movement. Once animals find a new habitat patch, they need to establish a new subpopulation. The third part of my research will look at the establishment of new subpopulations in variable environments. When subpopulations are small, random events have a large impact on the chance of success. I also propose to find out how population size affects survival probability, and how variability in conditions affects survival rate. This work would be carried out using beavers. The random events are storms that wash out dams. When dams are small, they are easily washed out by storms. I propose to survey dams over a large area, and then compare the success of the dams from one season to the next, as a function of dam size and size of storms.