The initial rise in global temperatures has already caused the altitudinal range limit of many mammals to have shifted upwards. Given the expected temperature increase due to global warming we can expect further dramatic spatial changes in species composition (Flojgaard et al. 2009). Evidence from the Last Ice Age has shown that European mammals have the capacity to respond to climate change, however, when taking anthropogenic threats into account, such as habitat loss, disturbance, pollution, overexploitation, and invasive species, these mammals may not be able to adapt to shifting temperatures. This paper discusses possible consequences of climate change and the effects it might have on Danish mammal fauna. Climate models for Europe at the end of the 21st century generally show a climatic shift in a north-eastern direction, with Denmark displaying a relatively stable climate over the next 100 years. Denmark currently has a highly fragmented landscape of natural habitats and intensely managed agricultural land and urban areas. Over the last thousand years, this has led to the extinction of many mammals, most notably moose, aurochs, lynx, wildcat brown bear, wolf. More recently, in the last 100 years, species such as the bank vole, European polecat, pine marten, and badger have all experienced population declines due to habitat loss and fragmentation. Estimations based on models and literature reviews show that climate change will cause a general enrichment of mammal fauna in Denmark. Only one species was found to be highly threatened with extinction. — Patricio Ku
Flojgaard, C., Holme, N., Skov, F., Madsen, A., Svenning, J, 2009. Potential 21st century changes to the mammal fauna of Denmark —implications of climate change, land use, and invasive species. IOP Conf Series: Earth and Environmental Science 8, doi:10.1088/1755‑1315/8/1/012016
The scientists focused on terrestrial non-volant mammals in this paper, and got their distribution data from the Atlas of European Mammals and the Danish Mammal Atlas. Climate scenarios were drawn using the A2 future climate scenario as modeled in the TYN_SC 1.0 data set, which is commonly used in the prediction of species potential future distribution. The migration rate for mammals across modern European landscapes was modeled after two studies that observed the spread of introduced mammals in Europe. Finally, to select the most relevant species that were judged most at risk of extinction, scientists used species distribution modeling to quantify their potential distributions under present and future climatic conditions.
The results showed that many species are within migration distance of the Danish border and could potentially migrate to Denmark during the 21st century and change the species distribution. Only one mammal, the northern birch mouse, was found to be at serious risk of extinction. Predictions of the species’ future distribution indicate that climate change might be one of the biggest threats to this species’ survival in Denmark. A few other species were considered to be at risk due to competition with introduced species. Recently there has been competition between the introduced American mink and native European polecat, but this has not been considered a serious threat to the polecat. However, the American mink has caused a decline in the water vole population in the British Isles due to predation. Since there are so many species within migration distance it is very likely that they will immigrate over the Danish border. These species include: Millet’s shrew, Miller’s water shrew, bi-colored shrew, lesser shrew, common hamster, common pine vole, southern water vole, fat dormouse, and garden dormouse. The species just mentioned are all native to Europe and it is considered unlikely that they will cause problems to competing native Danish species. Most of the changes in species distribution will occur because of climate change and other anthropogenic factors. As a result, the future abundance of the species discussed will depend on factors like habitat restoration. Introduced species in Denmark will become an increasing problem, but will not have an extremely large impact on native species since many of them already coexist in other areas of Europe. In conclusion, habitats throughout Denmark are not in critical danger, but should be monitored closely in order to ensure that any negative impacts are met with management and conservation plans.