Sunday, 23 February 2014

Beetling about in flood debris

Anyone who's not been living under a rock for the past two months can't fail to have noticed that the country is slightly damp at the moment.  Large chunks of Somerset, Oxfordshire, Berkshire and others have been underwater as rivers reclaim their flood plains, while the sheer volume of water has saturated the soil, leaving rainwater pools on the surface.

Of course, floods are horrendous when they affect your property, family or livelihood, but if you're interested in insects and other invertebrates, they can also provide something of a bonanza.  Huge numbers of invertebrates - snails, harvestmen, beetles, and more -  live in the soil, amongst roots, in leaf litter or at the bases of grass tussocks, and at this time of year they're joined by a whole load of extra species that go there to spend the winter.  When the water rises, these invertebrates are flooded out and washed downstream with all the other flotsam and jetsam - litter, sticks, etc.  This all accumulates in heaps of debris around obstructions, and picking through these mounds can turn up all kinds of species.
Flood debris collecting between the bank and a narrowboat
My local river, the Thames, has been flooded to varying degrees since Christmas, and I've been out a few times to see what's been washed up.  The main groups  have been beetles and snails, both terrestrial and freshwater.  Probably the pick of the 27 species of snails that have turned up so far has been the ribbed grass snail, Vallonia costata - a species I'd only ever seen once before, at last year's Bristol bioblitz.  Although it's only 3mm long, the ribbing combined with Mick Jagger lips makes it both distinctive and (for a snail), really rather attractive.
Vallonia costata, photographed down the microscope
Something I hadn't ever seen before was a tiny but very smart harvestman, Nemastoma bimaculatum - black and leggy with two white flashes (hence bi-maculatum).  By far the biggest fraction in the debris  has been beetles, particularly carabids (ground beetles) and staphs (rove beetles), but some smaller stuff has turned up as well.  Some has been impressively small - one that I've yet to do anything with is a featherwing beetle, family Ptiliidae, well under 1mm long!  Because there's so many beetles they're a bit on the back burner until my PhD corrections are finished, but all the other species, plus a bit of judicious lichen-spotting in the back garden, have taken my 1km square list up past 300 for the year - well on track for four figures by year's end!
Nemastoma bimaculatum from flood debris
A still-mysterious featherwing beetle, Ptiliidae sp. Image width approx. 1.5mm!
Flood debris beetles waiting to be identified - mostly carabids, particularly Bembidion spp., but also Heteroceridae, Aphodius, Hydrophilidae, mostly Cercyon spp., and some Chrysomelidae in tribe Alticini

Monday, 17 February 2014

Slightly further afield...

A slightly busy week last week - my PhD viva, two days of a bumblebee meeting in Southampton, and some filthy weather meant I didn't get out into my local patch, other than running to and from the car in the pouring rain.
My local patch, currently.  Not pictured: dry land
Come Sunday though, I'd arranged to brave the floods and meet up with some friends down in Somerset. Despite the non-stop news pictures, most of Somerset is well above the current high-water mark and we all made it to Shapwick in time for for the sun to come out.  After a quick sit-down for coffee and cake, watching small birds on the feeders - Coal tits and Reed buntings new for the year, Collared doves clumsy as ever - we headed down the road to the Hawk and Owl Trust's new reserve at Shapwick Moor
Glastonbury Tor from Shapwick Moor, looking across the grazing pasture and rhynes.
Not many birds about, but some nice snails in the rhyne dredgings, notably the Viviparous snail (Viviparous viviparous) and the Greater ramshorn (Planorbarius corneus), and, in the sandbanks, marine bivalves dating back to the last ice age. A quick lunch stop later, and we were off again, walking down past the route of the Sweet Track, a 2 km wooden walkway built in 3806 BCE and abandoned after less than a decade due to rising water levels, a fate it was suffering all over again with the last month's rain.  It wasn't the only casualty we saw - once ensconced in the hide at the far end of the track, we could see three or four fresh scars in the peat where trees had been blown over that week.

We weren't the only ones to have noticed: a flash of orange and electric blue announced a kingfisher, eagerly prospecting the new earth banks for a nest site.  Overhead a marsh harrier drifted slowly, wheeling effortlessly in the blue sky. As dusk fell, four lapwings flapped lazily by; one of Britain's handful of great white egrets swooped low over the reedbeds; swans slid smoothly across the reflection of the setting sun; several thousand starlings buzzed us, hurtling low overhead with a susurration of wings, as if the reedbed had taken to the skies. Summer's great, but winter has plenty to recommend it if you know what to look for!

Casualties of the storm.  Somewhere in this picture is a kingfisher, but it was a long way away...
Glastonbury Tor, from Shapwick heath
Reedbeds at Shapwick heath
It's important to have all your ducks in a row
Reedmace, Phragmites and ducks
Settling down for the night

Tuesday, 11 February 2014

What's lurking in the Oxfordshire undergrowth?

The prey shifts nervously, raising its head from grazing under the hunter's multifaceted gaze.  Sensing oncoming eight-legged movement, the would-be prey item strikes out with its forked tail, catapulting itself backwards and spinning head-over-heels through the sky as the pincers of the wannabe-predator close on empty air.  This is the seriously weird world of the British microfauna, and it's at least the equal of the charismatic macrofauna you can see on TV.

Pseudoscorpions - the thwarted predator from the scene above - are symptomatic of how this miniature jungle is overlooked.  They look amazingly similar to 'real' scorpions, complete with huge pincers, but lack a sting at the back end.  Although they look far too exotic to be British, in fact we've got at least 27 species and many are quite widespread, particularly in moss, leaf litter, and under bark.  I found this one - Chernes cimicoides - under the bark of a dead Eucalyptus around the corner from my house last weekend.
Chernes cimicoides
Having wandered down to the river Thames to see how high the floods were getting (answer: worryingly high), I spotted that the dead tree had some loose bark and had a bit of a poke around underneath.  These kind of sheltered spots are some of the best places to find insects over the winter, and there were plenty here - woodlice (Porcellio scaber and Androniscus dentiger) scuttled in all directions when exposed to the light, while bean weevils (Bruchus rufimanus) tried the opposite tack and froze, pretending to be lumps of misshapen wood.  Ladybirds (Harlequin Harmonia axyridis and 2-spot Adalia bipunctata) trusted in their defensive chemicals and warning colouration to repel me, sitting in obvious groups, and it was when peering at these (I'm very fond of ladybirds after studying them for four years for my PhD!) that I noticed a 3mm flattened, rounded blob tucked in nearby.  Spotting the pincers I almost jumped for joy - my second ever pseudoscorpion!
Chernes cimicoides in its overwintering cell underneath bark
Reaching 3mm long in Britain and only up to 12mm in the largest species yet found worldwide, these tiny arachnids are close cousins of spiders, harvestmen, scorpions, mites and ticks in Britain, and of whip-scorpions, vinegarroons and camel spiders overseas.  They may not be cute and fluffy but they are amazing to look at, and in their habits - the first I ever saw was in a photo that a friend had sent me to identify a beetle.  When you looked closely, an odd bulge on the antennae was clearly a pseudoscorpion, clinging on for grim death as the beetle unwittingly flew it to pastures new.  And when was the last time you saw a lion do that?
A pseudoscorpion on the antennae of a Black-headed Cardinal beetle (pic courtesy of Jo Cartmell)