Wednesday 24 June 2015

A Pucker Pair of Pygmy Shrews

Hemel & Bovingdon (BMT): Last week was surprisingly productive....except when it came to blogging. Prepare yourself for an eclectic preamble before we get to the main inspiration for the title. OK, so, I did a few bordering-on-the-obsessive butterfly and moth counts at various BMT sites last week. Once you’ve strolled and counted in one meadow, it is weirdly difficult to resist the urge to stroll and count in another meadow, just to see what else might turn up. Anyway, the best of the butterflies were 2 tired looking Painted Ladies (one at the Brickworks, one at Bovingdon Reach meadow); my first ever Brown Argus at Bovingdon Reach meadow along with a very worn migrant Rush Veneer (Nomophila noctuella) moth. My first Marbled Whites of the year. A few amorous gatherings of Yellow-barred Longhorns (Nemophora degeerella) and my first ever Hummingbird Hawk-moth (Macroglossum stellatarum) at the Brickworks, which was superb. I chased it around the Birds-foot Trefoil, but it didn’t stop for a photo op.

This time of year is wonderful for finding bundles of baby birds, often just fledged. I came across a group of at least 6, probably 8, tiny, newly fledged Wrens, still sporting their yellow gapes, in Hay Wood on Wednesday. The light was terrible unfortunately so no decent photos. On Thursday, it was Nuthatches at the Brickworks. Again, there could have been up to 8 little ones, all together, moving noisily through the trees. The head markings on the young aren’t so well developed so they can look a bit scruffy but still very sweet.

On the flora front, I counted the Bee Orchids (Ophrys apifera) on Bovingdon Reach meadow. It’s not the easiest of tasks. One wrong move and you’ve crushed rather than counted the specimen! Anyway, I got up to 87 spikes, no casaulties, and there’s bound to be ones that I’ve missed, so, roughly 100 or so plants which is fantastic.

Finally, in the gloom and drizzle on Saturday, I came across a wonderful stretch of Wild Strawberries (Fragaria vesca) at the Brickworks. It’s not a species listed on the 2011 plant survey so must be a fairly recent colonisation. I don’t think I’ve ever seen so many plants all in one place - it really was a Summery, cheerful sight. And, on the fauna front, I picked up a couple of dead Shrews, both on the path but at different locations.

OK, to the Shrews!

....after doing a fair bit of reading and hearing from a couple of well informed, experienced and licensed mammal handlers, it turns out the two I picked up on Saturday were Pygmy Shrews (Sorex minutus).

From my limited experience, it’s not actually that easy to separate Common and Pygmy Shrews, especially if you happen to find a large Pygmy or small Common with a tail that is close to the tolerances of either species. However, the guideline features seem to be as follows and, considering the 'the sum of the parts', it is possible to tease out the correct ID:

Common Shrew (Sorex araneus)
Pygmy Shrew (Sorex minutus)
Body length48-80mm40-65mm (but could be up to 72mm)*
Tail length24-44mm32-46mm
Tail length relative to body lengthusually 50%usually 65-70+%
TeethRed tippedRed tipped
Tail featuresYoung have furry tails, adults have a few stiff hairs underneath and bald on topProportionally longer, thicker and hairier than the other shrew species
Fur colourTri-coloured (dark brown back, paler sides and grey/white underside)Two-tone (brown back, pale underside)
ActiveMainly nocturnalDay and night

[*A mammal expert on ISPOT provided some very helpful information, noting that the head-body range given for Pygmy Shrews in field guides is 4-6.5cm in one (UK) and 4-7.2cm in another (Europe and Middle East). Interestingly, the latter book noted that size increases from north to south and from east to west, and Britain is at the western end of this shrew's range.]

The two Pygmy Shrews (Sorex minutes) I found were actually identical in their measurements:
  • Body = 65mm
  • Tail = 40mm
  • Tail relative to body = 61%

As with the Common Shrew in April, unless you have a license to trap and handle live mammals, it's rare you get to see these creatures up close, especially when they are in good condition. One of the two I picked was as fresh as the proverbial daisy (except for being dead, of course!).

Two-tone coat, with fairly clear demarcation between brown upper and pale underside

Back foot (underside)

Back foot (side view)

Front foot (upperside)

Front foot (underside)

Red-tipped teeth and pointed nose

For more info on Pygmy Shrews, see THIS great article. It includes such facts as individuals needing to eat 1.25x their body weight in food per day in order to survive. And, they can die of starvation if they’re not able to feed for a couple of hours. It’s not surprising it’s a species with a maximum lifespan of 13 months!

1 comment:

  1. Excellent! Thanks Lucy, I learnt a lot there, and it's a great reference tool!


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