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Introduction : Climate change and animal ecology are two finely related fields of study. Their interaction is notably observable through how climate change may alter the physical structure of faunal habitats. In cold environments, cases of such modifications are frequently observed due to the physical properties of water.
In fact, water freezing forms ice, an inherent characteristic of polar climate that has a great influence on habitat structures. However, numerous climate models predict a warming which, because of thawing, could lead to important geomorphological changes that may affect the ecology of various animal species.
For example, arctic foxes (Vulpes lagopus) dig and use dens on which they depend for protection and breeding. In the Canadian High Arctic, one main characteristic of these dens is that they are located in a frozen ground (permafrost) that is hard to dig so that the same dens are used year after year, sometimes during centuries. Foxes rely on the steadiness of these dens for the raising of their young, a crucial step of their life cycle. On Bylot Island, some dens that have been monitored for several years have now collapsed, which raises questions about the vulnerability of these structures to climate change.
Objectives: I will thus use the arctic foxes of Bylot Island as a study model to investigate the interaction between climate change and faunal ecology pursuing three main objectives:
(1) Characterize permafrost in which arctic fox dens are situated
(2) Estimate to what extent permafrost degradation could have caused the collapse of certain dens
(3) Assess the vulnerability of dens on Bylot Island regarding the upcoming global warming.
Study site: The study site is located in the Canadian Arctic, specifically in the south plain of Bylot Island (Nunavut, Canada). The arctic fox population of the site has been monitored since 1993, and more intensively since 2003. Each year, from May to August, about 100 dens numbered and identified since at least 2003, are visited to determine if they are used by foxes. When this is the case, the reproductive success of individuals is estimated. Moreover, some other characteristics of dens are also measured (number of burrows, presence of ice in burrows, number of collapsed burrows, etc.).
Objective (1): Using geomorphology techniques, I will characterize the grain size and water content of permafrost of each den, together with the type of soil in which they are situated.
Objective (2): With the already existing database, I will characterize the extent of den collapse in the last decade, and determine whether these collapses are correlated to certain characteristics of permafrost.
Objective (3): Using available climate change scenarios, I will qualitatively assess the vulnerability of known dens according to the type of permafrost in which they take place.
Anticipated results: According to the scientific literature, thawing of ice-rich permafrost is more likely to give rise to soil instability and mass movements causing landscape changes. Furthermore, soils having a fine grain size composition favor ice segregation, a process that forms ice lenses when the volume of ground ice exceeds the total pore volume of the sediment. Thawing of these ice-rich zones also promotes slope instability and rapid mass movements. Thus, I expect to observe the existence of a correlation between the number of collapsed burrows per den with higher soil water content and/or finer grain size.