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Small mammals

Small scale predators

There are five species of insectivore in Scotland: hedgehogs, moles and common, pygmy and water shrews.

Shrews live their short, busy lives in the fast lane. Their very high metabolic rate means that they need to eat 80-90% of their body weight (in the form of hundreds of small invertebrates) every day, and nearly twice this when feeding young. If deprived of food for more than a few hours they will die. They are territorial and frequently aggressive to one another. Dead shrews can sometimes be found lying out in the open. This is perhaps surprising given their size and vulnerability to a predators, but explanation lies in the scent glands located along their flanks which produce a distasteful musky odour. Despite being unrelated to mice, they were sometimes referred to as 'thraw mice' in folklore and were formerly subjected to persecution owing to the belief that if one was allowed to run round the feet or hands the limbs would lose their power for ever afterwards. It was even thought that they could cause death to cattle! Such superstitions may have arisen from their distasteful properties. Shrews are actually beneficial to humans because they consume so many leatherjackets, caterpillars and plants bugs.

Moles and hedgehogs occur over most of mainland Scotland and a few islands including Skye and Mull. Hedgehogs were introduced to the Western Isles (South Uist) in the 1970s and now number over 7,000. Their predation of the eggs of ground-nesting birds, particularly in the machair areas of the Uists has resulted in the establishment of the Uist Wader Project.

Moles are at their most abundant in deciduous woodland with its abundant invertebrate life although you will see few molehills because the tunnel systems are less often damaged and can be handed down from generation to generation.  Fortunately for moles they are able to adapt to agricultural land where their hills are more frequent.  In Scotland they also occur at low density in coniferous forests, moorland and sand dune systems. 

Rodents

Rodents are generally perceived as agricultural and domestic pests but include threatened species such as the red squirrel and water vole and island specialists like the St. Kilda mouse, Orkney vole. Abundant species  such as the field vole and the wood mouse play a critical role in the food chain.  Their numbers in some cases regulate populations of our larger predators. Rats are a conservation threat on some off-shore islands where they can seriously affect our internationally significant seabird colonies



Last updated on Friday 23rd August 2013 at 11:55 AM. Click here to comment on this page