THE list of wild mammals in Ireland has grown by an astonishing amount over the past 100 years. Some of the new additions have here all along but they were animals we never noticed and includes several species of bat.
But there has also been a stream of new arrivals. The latest appears to be a little mammal with a large name — the greater white-toothed shrew. It’s superficially mouse-like, though not remotely related to the mouse. Shrews are insectivores, related to hedgehogs and moles, and have strange snouts, like little elephant trunks. As the names indicate, the greater white-toothed shrew is larger than the pygmy shrew, which is one of our commonest wild mammals, but it’s still not very big. The pygmy shrew has a head and body length (not including the tail) of 45 to 60 mm while the greater white-toothed is 65 to 85 mm.
The white teeth are also significant. There are about a dozen species of shrew in Europe and most of them are very difficult to identify. The key thing is to look at their teeth. I have a zoology book that suggests you can do this with a live shrew by prising its lips apart and examining the teeth with a hand lens. I don’t think it’s as easy as this. Imagine taking a tiny and very cross little mammal with a snout out of a live-trap, managing to prise its lips apart and then getting out your magnifying glass to record the shape, number and colour of teeth that are virtually invisible to the naked eye?
Anyway, the shrews of Europe are divided into three genera. Our familiar pygmy shrew belongs to the genus Sorex which contains the red-toothed shrews, so called because their little teeth have red tips. Then there are the water shrews, genus Neomys, which are not found in Ireland, although there’s one species in Britain. Finally there’s Crocidura, the white-toothed shrews, which have normal coloured teeth.
The greater white-toothed shrew is a continental European species, not found in mainland Britain but present on Guernsey, Alderney and Herm in the Channel Islands. Curiously the first inkling it had arrived in Ireland came from an ornithologist: John Lusby of the Barn Owl Project found the jaw bones in pellets regurgitated by owls. It has since been recorded from counties Limerick, Tipperary and Offaly and is said to be spreading rapidly.
It’s believed the first animals arrived in Ireland from Holland in the root ball of a large plant imported to an Irish garden centre in a lorry that travelled via the port of Roscoff in northern France. We don’t know when this happened but they are now so widely distributed it was probably some years ago.
This is similar to the story of the colonisation of Ireland by bank voles. They arrived in soil left in the buckets of earth-moving machines imported from north Germany to the port of Foynes to construct the Ardnacrusha dam in the 1920s. But they were not discovered by science until the 1940s and the full story of their introduction was only unravelled the in last couple of years.
Greater white-toothed shrews, along with a couple of other shrew species, engage in a fascinating piece of behaviour zoologists call ‘caravanning’. They make nests to breed in and, apparently, if a nest is disturbed, all the shrews line up behind Daddy and each one grasps the tail tip of the animal in front in its snout. They then trot off in a connected line to look for somewhere safe to hide with no danger of anyone getting lost.
I’ve never seen this, not even on film, but it does conjure up rather an endearing image.
* dick.warner@examiner.ie
a d v e r t i s e m e n t
This appeared in the printed version of the Irish Examiner Monday, November 24, 2008
