When you think of endangered species, foxes probably aren’t the first animal to come to mind. In the UK, foxes can be found in Urban areas in abundance, and one or two probably make an appearance in your garden from time-to-time. In the Arctic, on the other hand, it’s an entirely different story.
On an island in the Bering Sea in the 1970s, a population of Arctic foxes began to mysteriously decline. These were thin and mangy animal, nearly all of whose cubs died. As it stands, there are only about 100 of these Arctic foxes left in the world – but why the decline? Until now, scientists have surmised that the animals were not felled by an infectious disease. However, according to a new study, published in the Public Library of Science journal PLOS ONE, has discerned a new cause of death: our poor environmental wellness.
The researchers, led by N. Bocharova, found that the Arctic foxes probably suffered from high mercury exposure as a result of eating seabirds and other marine animals. For their study, Correlates between feeding ecology and mercury levels in historical and modern arctic foxes (Vulpes lagopus), the team of scientists studied fox fur samples from four sources. These samples came from Mednyi Island, where the population crashed; museum specimens of foxes from the Commander Islands; and two populations in Iceland.
While one of the groups mostly preyed on land animals such as mice, the other three, which included the group of foxes from Mednyi Island population, ate marine animals. The team of researchers found that the mercury levels in this latter group of foxes – those with the marine diet – were almost three times higher than in foxes with an inland diet. So why were the Mednyi Island population of Arctic foxes the ones who suffered the most?
Of the three groups of Arctic foxes that ate marine animals, the two, non-Mednyi groups also dine on land animals. The Mednyi Island foxes, on the other hand, rely exclusively on marine animals for food. The researchers also analysed the Mednyi Island foxes’ blood, skin, and faeces for signs of dangerous infections, but as most of these tests came back negative, the researchers concluded that this indicates that pathogens weren’t responsible for the population’s collapse.
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