Pygmy shrew (and flea) accidentally trapped at Nedd

December 17th 2014

Pygmy shrew (and flea) accidentally trapped at Nedd

On 24th November, I was inspecting what I had fondly thought were a fine row of neeps in our vegetable garden at Nedd. Under their spreading tops, I discovered that at least half a dozen had been hollowed out. Small rodents seemed the likely culprits, and since we grow neeps for our consumption, not theirs, I put down mouse traps. These I baited with cheese, and placed them in three tile drainpipes (to prevent access by birds).

Since then the traps have caught thirteen wood mice, two bank voles, two pygmy shrews and a water shrew. Shrews were not the intended quarry. I have now removed the traps, and turned the damaged neeps into soup.

The pygmy shrew caught on 8th December is illustrated in the attached photos. It has the relatively long tail (c.40mm, 70% as long as the head and body) which distinguishes it from the larger common shrew. It weighed about three grams, indicating that it was still immature. Adult pygmy shrews can weigh as much as five grams!

Shrews live for only about 18 months, being born one spring, and, if they are lucky overwinter. They then breed the following year and dye in the autumn.

This pygmy shrew was accompanied by a flea, which I collected and am having identified. Since there are few records of shrew fleas (or almost any others) from the north of Scotland I await the result with interest.

Ian M. Evans

Update – Flea on pygmy shrew, Nedd

The flea mentioned above has now been identified. Frank Clark from Leicestershire, confirmed it as a female Amalaraeus penicilliger mustelae. This is a species most commonly associated with voles, especially the bank vole, but which has also been found on most other species of small mammal in Britain.

I have had it on five previous occasions in Assynt. These are small mammal nests at Glenleraig, Nedd and Oldany, a bank vole trapped in our garage at Nedd and on a weasel found as a road casualty at Skiag Bridge. Lest anyone think that flea identification is a pushover, Frank informs me that he had to de-sclerotize the specimen. This is done in KOH ‘in order to see the relevant bits’ under the microscope.

Fleas are an under-worked aspect of the biodiversity of Assynt, of interest because many are very specific as to host (unlike A. p. mustelae). I have had ten species from a range of situations, including those mentioned above. Others include bird nest boxes, nests of house and sand martins, a cat and pipistrelle bat. However, never, so far, from mole or badger, both of which host very large fleas.
It is reassuring that this particular species is marked NKBH?, i.e. Not known to bite humans!

Ian Evans 5.2.15

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