Eye Spy an Otter

Whilst our ecologists were carrying out a survey for great crested newt earlier in the week, they were lucky enough to spot an otter! This species is instantly recognisable given its brown coat, flattened head and thick tapering tail. Unfortunately its appearance was only fleeting (as is ever the case with this shy species) as it made its way to a nearby lake, jumped in and rapidly swam out of site. Otters are extremely adept swimmers, using their webbed feet and thick tail to propel themselves through the water.

Otters belong to the same family as badger, polecat, mink, ferret, pine marten, stoat and weasel, known as the Mustelidae family. Otters are usually nocturnal, although at this particular site they are routinely spotted during the daylight hours. Otters tend to reside at low population densities, so their territories usually cover large areas. For example, the average home range of a male otter is 32km of river habitat. An otter’s diet comprises mainly of fish and so the amount of time that they spend in any part of their territory is dependent upon the abundance of fish at that time. In the spring, when fish stocks are lowest, frogs and toads become an important prey item with mammals and birds taken only occasionally.

Given that otter are generally nocturnal, field signs are the best clue to identify that this species is present. Otter faeces (known as spraints) are usually black or greenish-black in colour and often contain fish bones/scales and high levels of mucus. The most characteristic feature of a spraint is its distinct sweet (but fishy) smell, as opposed to the repellent smell of mink scats. Frequently found otter feeding remains include: the hard parts of crustaceans, the unpalatable bits of amphibians and the bony parts of fish. Paw prints left by otter are approximately 6cm wide and have five toes, however, on hard ground, only four show.  Marks, left by the webbing between the toes, are sometimes visible in the print as are the marks left by their sharp claws.  Can you identify the otter paw print in the photo?

 

Fresh otter tracks River Isla NR

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