Sunday, 22 January 2017

Otter Signs

South of the village the streams flow east to the Cherwell and eventually the Thames and the North Sea.  They arise as springs west of the village from the surrounding limestone.   The village itself  stands on the upper lias, the Banbury ironstones.   A bright, frosty morning we went for a walk along the side of one stream and back along another.  There are several badger setts along the route, but several have been damaged by renewal of a power line a few months ago, where trees and understorey were cleared.  The setts are still there, but are now  fully exposed to the world.  

Badger territory

On every streamside I look for otter spraint; there have been otter sightings to the east in Grimsbury near Banbury and to the west 5 miles away on the Glyme just south of Chipping Norton, I found several sprainting sites last year.  Nothing though near the village, until today.

I rather suspected there might not be enough food near hook Norton for otters because the streams are quite modest, but there are several privately-owned fishing ponds around some of the rather more expensive properties.  Otters have spread rapidly in Oxfordshire since they were first seen in the county around 20 years ago.   In fact we were among the first to find spraints at that time - on the River Evenlode near to Daylesford - meeting suspicion and incredulity about the find.  Now otters seem to be near the village; I found one spraint on a rock mid stream not far from a fish pond.  There were also some partial prints in the stream bank, together with badger prints.  Almost certainly this was a casual visit (males will range as much as 20 km in a night, females a little less), probably helped by there being more water in the streams following heavy rain last week.

Otter spraint

I brought the spraint back to look at the food remains and my study now reeks of the it, that unmistakable sweet fishy smell.   So if anyone has never smelt the stuff....!  Had it been mink I would probably have had to move out, as they stink; they look similar to otter spraints but they are just bad.

Wednesday, 18 January 2017

Still Fixated by Knopper Galls

Yes, I haven't moved on (partly because there is not much else of note under the unrelenting grey skies, but then the galls continue to surprise).  In the last few days many more insects have emerged from the knopper galls that I collected from under a common oak (Quercus robur) in the third week of December, and subsequently kept in a closed container at a steady 20℃.  From the 14 galls of different shapes and sizes so far  there have been   6 of the alien host gall wasp Andricus quercuscalicis.    These are from the agamic, that is, non-sexual generation, and are therefore all female.

But far more numerous,- more than 60 - other insects have emerged.   All look very similar and I am reasonably certain that they are almost all parasitoid wasps with perhaps one or two of iniquiline wasps among them.  Parasitoids attack the host wasps that create the gall in the first place, whereas iniquiline wasps simply take up home in the gall - uninvited lodgers that can alter the shape of the developing gall.

It does make for a puzzle.   A paper from 1991 by Hails and Crawley (J. Animal Ecology 60 (2) 545 - 61) found little parasitism in the non-sexual generation i.e the galls on common oaks, unlike in France where there was much more activity by parasitoid wasps.  A more recent paper  however by  K Schonrogge et al ( Insect Conservation and Diversity, 5 (4). 298-311) lists 14 parasitoid wasps and 5 iniquiline wasps associated with knopper galls, all as far as I am aware UK natives.   Knoppers are a recent introduction so maybe over time native parasitoid wasps are adapting to the alien.

I counted 55 of the emerging wasps and grouped them on size and appearance.   My summary for which there are photos below was:

Type A 3.5 mm long    29  (metallic sheen)
Type B 2 mm long       22  (very similar to type A, but smaller)
Type C 2 mm long         2  (metallic green with bright yellow legs)
Type D  3.5 mm long     1  (all black)
Type E  2 mm long         1  (almost all black)

Attractive little beasts and as my wife tidily summed it up "lost to the world, no-one sees them".

Here is the gallery with some attempt at identification, or more precisely speculation.

Type A (maybe Mesapolobus amaenus or M. tibialis)


Type B (very similar to Type A, but smaller maybe a different sex (?), Mesapolobus amaenus or M. tibialis perhaps)


Type C (maybe Mesapolobus sericeus)

Type D ( maybe Eurytoma brunniventris)


Type E (perhaps the only iniquiline,  maybe Synergus sp.)


Tuesday, 10 January 2017

Emerging Knopper Gall Wasps and an Unofficial NYD Plant Hunt

In September, the Common Oaks nearby had been affected by knopper galls, and I have been fascinated by the peculiarity of these galls since.  In late December I collected 14 galls from under an oak and kept them at home.   The gall wasps (Andricus quercuscalicis)are now emerging, the first around 1st January, then one on each of 7th, 8th and 9th January, and one today.  Clearly this is earlier than would happen in the wild, as they have been kept at a temperature of 20℃, but it has meant a chance to look at the wasps.

Only the female affects Common Oaks; the sexual generation is restricted to Turkey Oaks.  These are close ups of the female.   The body length is around 4mm and the wing 5mm.

Another, smaller, insect has just emerged from the galls, but as it is only 2.5mm long then ID might be challenging.

BSBI's New Years Day Plant Hunt officially ended I think on day 4.  Surprised at how few species I found in and around Hook Norton, on the 5th I walked from Traitor's Ford up to Gallows Hill over to Sibford Gower and back to my starting point, a couple of miles north-west of the village.

Traitor's Ford might have got its name in the civil war - the battlefield at Edgehill is not far away, but it could also be a mispelling of 'Trader's Ford'.   (I am reliant on the local history society's webpages). The Ford crosses the River Stour which rises near Wiggington, east of Hook Norton.   We are on a significant watershed such that the Stour flows west, ending up in the Avon and Severn, whereas the springs and streams through the village and to the south flow east into the Cherwell and on to the Thames.

I wrote an almost new car engine off in the Fords some years ago.   The water was quite high, but the car in front got across without any issues.  So keeping the revs up I crossed the river.   Unfortunately the engine had a turbo, and the air inlet was under the engine  (unlike the rally version of the car where the air intake was above the engine).   With high revs it sucked up water at pace through the inlet and into the engine.  A deep intake of breath by the AA rescue man suggested expensive damage and he was right.

From Traitor's Ford the route followed a couple of green lanes to Sibford, and then back across pasture and arable, where mercifully the frozen ground made walking easier.  Great views but very few plants in flower, a total of only 7.   Surprisingly there were very few in Sibford village, a single primrose and autumn hawkbit but none of the weedy plants seen three days earlier in Hook Norton.
Ditchedge Lane

Path to Sibford Gower

Autumn Hawkbit

Traitor's Ford

Monday, 2 January 2017

New Years's Day (+1) Plant Hunt - a Few Weeds

Delayed by rain yesterday we took part in the BSBI New Year's Day Plant Hunt today.  Cold and sunny in complete contrast to yesterday's rain we were out for 2 hours, covering 4.6 km across the village over a couple of pastures and then one arable field, following roughly the same route as 2016 bit without an extension to the north.

 Our total was only 11 species, which compares to 21 last year (8 the same, 3 new and 13 not found this year).   None of the early spring flowers were in flower; for example a few snowdrops were in bud but nowhere near opening up, but then December 2016 was colder and drier than in the previous year. The average minimum temperature drawn from my wife's records was 3.4°C (2015: 8.2°C) with 7 nights of frost (2015: 0).  The rainfall total was less than half that of 2015 at 30mm in the month (2015: 68mm).

What we did find therefore were a few common and persistent weeds, though fewer than in 2015.   The village is now kept 'tidier' by a part-time village warden, such that weeds are cleared out.  Here are some of those weeds:


Red Dead-nettle


Common Field-speedwell


White Dead-nettle


As ever the arable field proved very dull, and the only interest was a nice clear badger print on the footpath crossing the field.