Messing about on the river: wildlife in the River Tale, Escot

http://www.escot-devon.co.uk/Messing-About-on-the-River/Event/28-July-2013

Now, I love watery wildlife, and had been pestering Sally for a chance
to come to work with her one weekend so I could poke my nose in the
wetland habitat there, so I was very happy to be allowed to tag along
this Sunday. There was raft racing, clay pot making, dam building, and
all manner of other activities, but obviously the most important thing
was the Day List of Species, so here goes…

While the kettle was boiling, I had a wander along the banks. A number
of insects were warming up and having breakfast on the daisies and
thistles, including pollen beetles, mirid bugs, and a great variety of
hoverflies. A number of black caterpillars could be found along the bank
– I think these were caterpillars of peacock butterflies (Inachis io),
but none were reported to be found on their food plant, the nettle.

Among the leaves of docks on the banks, I found some eggs and a number
of heavily pregnant and wonderfully coloured Green Dock Leaf Beetles
(Gastrophysa viridula), and I guessed the eggs belonged to the beetles.
(They did – http://www.reddishvalecountrypark.com/#/green-dock-beetle/4554601367)

A big greenish dragonfly started patrolling our stretch of river – one
of the hawkers, but I didn’t get a proper look at it. There were a few
damselflies drifting about – one of the Coenagrions, we decided.

The largest visitors to flowers were bumblebees – brown carder bees, and
one of the white-tailed bumble bees, Bombus lucorum or B.terrestris; the
queen of the British race of B.lucorum has an off-white behind, but you
have to get quite close to the workers to tell the species apart.

A Cabbage White Butterfly wandered through the site during the day, and
someone netted a froghopper, the adult of the grub that lives in cuckoo
spit, which must have fallen in from the bank.

Further investigation of the land insects was possible, but I avoided
the kamikaze pooter provided (one without a mesh filter, suitable only
for those who aren’t getting enough insect protein in their diet).

Meanwhile, most excitement was generated of course by what was coming up
in the nets.  We had at least five species of freshwater fish:
Minnows (of all sizes) Phoxinus phoxinus
Bullheads Cottus gobio (a fish I call the Miller’s Thumb – obviously a slightly clumsy miller)
Three-spined sticklebacks Gasterosteus aculeatus aculeatus
Stone loaches Nemacheilus barbatulus
and a number of small Eels Anguilla anguilla, which were pleasing to see.

Eels are under threat in this country (and elsewhere) as their habitat
disappears. Lindsay was amazed to hear about the life cycle of Eels:
adult eels swim downstream to the coast, and travel far to breed in the
Sargasso Sea, off the south-east coast of America, then their young swim
over 3000 miles back to the rivers where their parents grew up.

The most common invertebrate finds were many, many mayfly larvae – some
species with two and and some with three tails – and gammarid shrimps.

I was happy to meet some stonefly larvae – unknown in my native Fens –
which, having read one of Yog’s excellent ‘wet feet’ leaflets, I now
know are an indicator of good water quality.

In the muddier areas under trees were bloodworms, larvae of Chironomid
midges.  I think the red haemoglobin helps them absorb what little
oxygen there is in the river bottom.  With the bloodworms were other fly
larvae, I’m sorry to say I don’t know what they were.

What else… oh, several ‘true’ bugs, the little guys with beaks: the
lesser water boatman (Corixa), the pond skater (Gerris lacustrus), and
the water cricket (Velia caprai).

I have a curious fondness for beetles (as God is rumoured to do), but
they are fiendish things to identify. So I will say that we found a
number of water beetles of more than one family – and without spending a
bit more time on them, we’ll have to leave it at that!

Another beetle found among the gravel was identified by Mike as a
‘riffle beetle’ – which looked to me like a small ground beetle – and
could even have been just that, we weren’t sure…

We could be more confident about the identity of a small number of
whirligig beetles (Gyrinus, probably G. substriatus), and all agreed
that they have a very fitting name. They are the only insect I know
with bifocals – to be able to focus above and below the water surface.

The insect find of the day was Mike’s: a female Golden-Ringed Dragonfly,
Cordulegaster boltonii, found immobile in the river, drowned or
drowning. We displayed it in a small dish, but as it showed a bit of life
later in the day, it was then left in some sheltered vegetation to dry
out. When I checked later, it had gone.

http://www.dragonfly-images.co.uk/#/golden-ringed-dragonfly/4531807174

Thanks to Alun Bruford and colleagues for organising, and all hats
should be tipped to Yog, Mike and other colleagues from the Environment
Agency and other organisations.

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2 Comments

Filed under science & natural history

2 responses to “Messing about on the river: wildlife in the River Tale, Escot

  1. Pingback: River dipping again: messing about on the river 2014 | minorityattack

  2. Pingback: Messing about on the River, 2016 | minorityattack

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