Global Warming and Effects on the Arctic Fox

Article excerpt

ABSTRACT

We predict the effect of global warming on the arctic fox, the only endemic terrestrial predatory mammals in the arctic region. We emphasize the difference between coastal and inland arctic fox populations. Inland foxes rely on peak abundance of lemming prey to sustain viable populations. In the short-term, warmer winters result in missed lemming peak years and reduced opportunities for successful arctic fox breeding. In the long-term, however, warmer climate will increase plant productivity and more herbivore prey for competitive dominant predators moving in from the south. The red fox has already intruded the arctic region and caused a retreat of the southern limit of arctic fox distribution range.

Coastal arctic foxes, which rely on the richer and temporally stable marine subsidies, will be less prone to climate-induced resource limitations. Indeed, arctic islands, becoming protected from southern species invasions as the extent of sea ice is decreasing, may become the last refuges for coastal populations of arctic foxes.

Keywords: arctic fox, Alopex lagopus, Vulpes lagopus, global warming, climate change, Arctic, tundra ecosystems, missed lemming cycles, predators, sea ice

Introduction

It is now documented that global warming strongly will affect the distribution and abundance of both plants and animals. It is also recognized that the Arctic is especially vulnerable to climate change because global warming is most pronounced at high latitudes (1). The terrestrial Arctic is dominated by tundra (Table 1); that is land areas north of the latitudinal tree line. The arctic tundra constitutes about 10% of the land area on earth and is situated as a circumpolar, relatively narrow zone delineated by the boreal forest in south and the Arctic Ocean in the north (Figure 1). The arctic tundra is predicted to shrink under global warming as the boreal forest zone will be moving to the north (Figure 1). However, ecological processes and characteristic species within the tundra ecosystem are likely to be affected long before the open tundra becomes forested.

The arctic fox (Vulpes lagopus) is one of the most characteristic species of the tundra. In this article, we discuss how the anticipated warmer climate is likely to affect the arctic fox and the wider ecological relations involving the arctic fox.

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Biological characteristics of the arctic fox

Morphology and physiology

The arctic fox, which long was classified as the only species in the genus Alopex, has recently been placed in the genus Vulpes, to which most other fox species also belong. The arctic fox is among the smallest species in the dog family (Canidae), normally weighing between 2.5 and 4.0 kg. It is found in two colour types (morphs), white and blue. White foxes have a pure white winter coat, which in summer turns brownish-grey on the dorsal side and white on the belly. The blue morph remains dark or charcoal coloured all year round, but becomes somewhat lighter in winter. Blue foxes are most frequently found in coastal areas without sea ice and with little snow in the winter and the dark colour may serve as a camouflage in such habitats (2). On the snow-covered inland tundra and on sea ice a white winter fur is clearly the most cryptic colouration (Figure 2).

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Arctic foxes are very well adapted to a life in some of the coldest areas on earth. They have a short snout and short rounded ears which minimizes the heat loss through these parts of the body. In winter, they are equipped with an excellent insulating winter fur, which is extremely thick with dense under-fur and long guard hairs (3). Even the paws are covered by fur. The excellent winter fur has made the arctic fox a very valued fur bearer, and it is still harvested in many places in the Arctic. In addition to the winter fur, a thick fat layer under the skin contributes to the thermal insulation of the inner parts of the body. …