Saturday, 26 May 2012

Crouching naturalist, hidden dragon

At HESC, this morning, I was walking alongside one of the ponds and stopped to watch several species of damselfly in the vegetation at the water's edge.

Fortuitously, whilst using my bins to identify a particular individual, my gaze alighted upon a dragonfly larva, tucked away amongst the reeds and ready to emerge as an adult dragonfly after two years underwater.

By the time I had deployed my camera, the action had started, the larval cuticle splitting behind the eyes and along the upper surface of the thorax.

8.14am - the thorax bursts through the larval skin
8.15am - the head and eyes are withdrawn from the larval skin
8.16am - the thorax is now free of the larval skin
8.17am - the first few segments of the abdomen emerge
8.18am - as the adult hangs backwards, the compressed wings can now be seen
8.20am - the breathing tubes linking the adult's thoracic spiracles to openings in the larval skin are breaking
8.26am - a period of quiescence follows whilst the legs harden in the sun's warmth
8.36am - the adult springs forward and grasps the top of the larval skin
8.36am - the remainder of the abdomen is now withdrawn from the larval skin
8.36am - the pale, newly-emerged adult sits on the now empty larval skin or exuvia
8.40am - body fluid is pumped into the wing veins to expand the wings
8.42am - bigger...
8.48am - and bigger...
9.05am - and bigger...
9.12am - until they are fully inflated
9.27am - the fluid is now withdrawn from the wings and used to pump up the abdomen
9.42am - once the thoracic muscles are warm enough, the wings snap open for the first time
9.47am - wings and body harden in the heat of the day and the body starts to develop colour
9.53am - the wings are now starting to look capable of flight
10.01am - the adult dragonfly adjusts position and reveals the characteristic wing markings of a Four-spotted Chaser 
10.10am - nearly two hours after emergence commenced, the adult dragonfly takes her maiden flight and moves to a safer position in full sun
During this time, I was joined by Our Lass, who played her part in an excellent morning's odo-ing by finding a Banded Demoiselle in the Centre garden. Other sightings included Hairy Dragonfly and a host of damselflies: Large Red, Common Blue, Azure, Blue-tailed and Red-eyed.

Another visit in mid afternoon added Broad-bodied Chaser to the total, making 9 species for the day. Odo-tastic!

Friday, 25 May 2012

Vicarious living

Other than typing these words, I play very little part at the sharp end of this blogpost.

The scene: at work, mid afternoon. An email arrives. It's from Our Lass.

Odd, I muse, she rarely contacts me at work unless something's broken or developed a technical malfunction. Car, computer, television, light bulb, bottle opener, that sort of thing.

The email header suggests otherwise, however.

"Garden tick".

I surmise that she's either been bitten by a very small invertebrate or the nature-watching bug.

As it turns out, it was the latter.

The email went on, "Slow-worm by pond".

Now, you could count the number of times we've seen a Slow-worm, Anguis fragilis, on the fingers of one hand. And none of the sightings have been in Milton Keynes.


Predictably, I mail back, "Photo?"

"Too quick, " comes the reply.

So not too much of a slow-worm, then.

STOP PRESS, 27/05/12: After a two day stake-out, Our Lass spots the creature again. Once more, it disappears in an instant. I manage one glimpse and a photo at range.

Grass snake, Natrix natrix
Not good news for the local frog population!

Saturday, 19 May 2012


A slow start to the day this morning. Grey cloud, a little breeze and the ground wet from overnight rain.

For the second year running, Crows have nested in a neighbour's Ash tree. By this time last year, foliage had hidden the nest from view, so we weren't able to see when the young fledged. However, so far in 2012, the leaves are barely bursting from the buds. Our Lass and I watched the antics of the pair of nestlings, who were in a blur of frantic wing flapping, as they attempted to build up their flight muscles.

Following breakfast, a text from the Admiral alerted us to the presence of a Cattle Egret, Bubulcus ibis, which had appeared at Manor Farm quarry workings, a little further upstream across Milton Keynes. We needed some fresh air and a walk, so decided to try the footpath loop through this area, between the West Coast main line railway viaduct across the River Great Ouse and the Iron Trunk Aqueduct, which carries the Grand Union canal across the same valley.

Path, earth bank, gravel, factory. Just another wildlife walk
We parked just off Haversham Road, by the viaduct, and walked up through the fields to the buildings at Manor Farm. Conveniently, a birder had set up his x50 'scope here, looking down into the floodplain, and he had already located the Cattle Egret, so we were able to enjoy views of the bird, even at such a great distance. The peachy markings on head, front and back, characteristic of summer breeding plumage, were clearly visible. Using bins wasn't much use and I'd wisely left the camera at home!

Thanking our saviour profusely, we sauntered on towards the canal, whilst overhead, countless Swallows, House Martins, Sand Martins and Swifts careened through the air, hoovering up any insect brave enough to attempt flight in the cool conditions.

At the canal we turned right along the towpath and were amazed to find the world's most obliging Grey Heron. It stood stock still, by the path, as we walked past, not even batting an eyelid when I stopped to take its picture using the camera on my phone.

Just before we reached the Iron Trunk Aqueduct, we descended the steps back to the valley floor and followed the path between the river and the gravel workings. This area had recently been flooded, as is mentioned in one of the local wildlife blogs, but water levels have returned to normal once more. Occasionally, views of the quarry workings would open up through gaps in the banking. We stood at one of these for a while, scanning the area with our bins. Within a short time, we had located a Wheatear, a Yellow Wagtail, a Redshank, several members of a species of Ringed Plover (could've been Little or plain old Ringed, difficult at distance with bins) and, happily, the Cattle Egret. Common Terns were plunging into the river behind us and Lapwings were busy chasing away Crows from their nest sites on the shingle banks. Thinking about my ID quandary above, I suspect that whatever I say, it would be a Wronged Plover!

After the gravel extraction is completed in a few years' time, this area will become a wet woodland nature reserve, managed by the Milton Keynes Parks Trust. Obviously, the wildlife hasn't read the relevant documentation and has already moved in.

With nary a glimpse of the sun or much in the way of any warmth in the air, the sum total of visible dragons and damsels was zero. Oh well, next week promises to be hotter.

Thursday, 10 May 2012

Ruby, Ruby, Ruby, Ruby

Eh? What's this? His Tenseness is a Kaiser Chiefs fan?

Not as such, though in our family, their 2007 hit is very much pertinent at this time of year.

Large Red Damselflies have started to emerge from the Tense Towers pond, each leaving behind a tell-tale empty larval cases, or exuvia, prompting many happy shouts of "Zuvi, zuvi, zuvi, zuvi!" at their discovery.

The fact that the Large Red Damselfly is... er, red in colour, does make the choice of lyric all the more apt. And, as I have just discovered, 'Zuvi' is a girl's name derived from the Kashmiri word which means 'life'. The emergence of the adult damselfly from the exuvia constitutes a life change for the creature. It has recently undergone a metamorphosis, triggered by an increase in day length and Spring temperature. One of the most profound changes that occurs at this time is the switch from gill-breathing to air-breathing. The larva's gills are in fact the caudal lamellae, the three leaf-like appendages at the tip of the abdomen. During the last few days of metamorphosis, the larva has to breathe directly from the air, so will migrate to the water margin near a place where emergence can take place. Here, the spiracles on its thorax, which have been sealed during its underwater life so far, are now opened enabling it to breathe air directly (my thanks to the Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland by Brooks and Lewington for these details). Once this has occurred, the insect has effectively crossed the Rubicon (or Rubycon!), there is no return to underwater life and it must now carry on with emergence into a winged insect.

Fully grown larva in the final stages of metamorphosis on a Marsh Marigold leaf
Exuvia of a Large Red Damselfly on a dead Water Mint stem
The white thread poking out from the larval case is the remains of one of the tubes linking the spiracles of the larva to the outside world. These are left behind as the adult body emerges.

Monday, 7 May 2012

May in Little Linford Wood

Waking early on a work day is such a chore, but on a day off it can be a real treat. So it proved this morning. I rose from my slumbers at 6am and chanced a peek through the curtains. Not raining, hey, result!

In fact, there were a few breaks in the cloud letting the odd shaft of sunlight through, which was invitation enough to scramble into some clothes and gather together my optics for May's trip to Little Linford Wood.

As I drove through Newport Pagnell, there was an occasional patch of frost on car or shed roofs and the road in the river valley was still half-covered in flood water. Fancying a longer walk than normal, rather than use the usual car park, I stopped in the corner of a field, just off the tarmac road, and set off on foot along a broad path towards the wood.

In the distance, mist was blanketing the southern edge of the trees and, as I worked my way along a hedgerow, there was the welcome song of a Whitethroat, Sylvia communis. Another Summer migrant arrives! Nearing the wood, the weak sun had burnt off the mist and all was clear and crisp once more. It felt like the landscape had been freshly unwrapped and spread out in the warming light. The lush green growth of the leaves and the swathe of colour from innumerable Bluebells were still glistening in the early morning dew.

Arriving at the car park on foot, I startled a Buzzard, Buteo buteo, that was roosting in an Oak tree in the clearing. There always seems to be a pair of these raptors around the wood and they certainly have plenty of choice for a nest site.

Following the recent rain, I was pleased to find that the ephemeral pond by the car park was holding water again. Who knows, if we have a wet summer, this could once more prove to be a good spot for dragonflies.

On through the woodland paths and there were more signs of Spring. Greater Stitchwort is now in flower and there were a few specimens of Wild Strawberry (though as I didn't take a photo, I'm unable to say which species, sorry).

Greater Stitchwort, Stellaria holostea
The results of the wild weather of the past few weeks can still be seen. Here an old Oak tree has fallen across the main ride. No longer standing dead wood.

On the path to the west of the wood, I was fortunate to see a Hare across the field. It was sat in a furrow made by a tractor wheel, which at least rendered it visible, as the crop is now too high otherwise. As the ground was very wet with dew, I couldn't disagree with its reasoning. I had been employing much the same tactic, walking wherever the grass was shortest! The Hare was busy grooming (or just drying itself, I guess) and then with a final flourish, it sat up and boxed the air, before loping off along the furrow.

Up by the old barn, the songs of Chaffinch, Fringilla coelebs, Tree Sparrow, Passer montanus, and Lesser Whitethroat, Sylvia curruca(another arrival) could be heard. As I was trying to photograph a few of the sparrows, another pair of birds flew into the hedge and perched in my viewfinder. Linnets! (Carduelis cannabina!)

The skies were growing darker by this point, heralding a return to the prevailing dreary drizzle, but before that, I was allowed one more ray of sunshine in the form of a sumptuous Yellowhammer, Emberiza citrinella.

Here's hoping for some warm sunny days in June and the promise of insects on the wing.

Sunday, 6 May 2012

Damsel dilemma

What will the month of May deliver to the UK?

Following the third warmest March since records began and the wettest April that the Met Office can recall, Nature could be forgiven for being in a bit of a flap and somewhat confused in 2012. After the fantastic experience of recording a Large Red Damselfly on the 3rd April (admittedly much further south and west than the county where Tense Towers is located), things have been pretty lean in the Odonata department. As it turns out, the day after our sighting, the weather changed for the colder and then the wetter, so I guess it's not so surprising.

Yesterday, in a brief respite from the gloom and rain, there were a few sunny spells, though this was tempered by a bitingly chilly north wind. In fact, Our Lass, who is currently on a work placement in Orkney, reported that it had snowed on the islands that morning. Undeterred, the Admiral and I ventured to Walton Lake, on the west side of the Open University campus, to search for the first Buckinghamshire Odonata records for 2012. This site is usually one of the first in the area where damselflies (and dragonflies, if we're really lucky) emerge, as it has some sheltered pools and glades. As it was, the 5th May was an unprecedentedly late date to be searching for that elusive first ode in the county.

After scouring some likely spots, mainly south facing slopes with plenty of roosting vegetation, we eventually found two Large Red Damselflies. Both were mature individuals, so had probably emerged a few days ago. But that was it, just two.

In similarly vein, the Tense Towers pond has not yet shown any evidence of odonatological emergence by these harbingers of the flight season, nor the various pools and ponds at Hanson Environmental Study Centre. However, whilst checking out the latter, the Admiral did point out some Swifts overhead, the first ones I have seen this year.

Today, the weather has returned to grey skies. It remains cold and the forecast for the week ahead is for slowly rising temperatures with yet more rain. Whoop.

Thursday, 3 May 2012

Treatise on religion, natural history and heredity

Recently, I was perusing the book shelves at Tense Towers, where there are several natural history tomes which have been handed down from generation to generation. These books have been in my possession for some years, filed away amongst the varied subjects and titles of our own collection and the inherited sacred texts from my paternal grandfather, a lay preacher.

These latter texts are kept, not because we're particularly religious (for, in fact, we are particularly secular, just in a spiritual way), but rather because of the family connection. Although, as works such as 'Counsel and Comfort Spoken From A City Pulpit' and 'Altar Of The Household' aren't the "go to" books for wildlife ID, I rarely tend to browse that section of shelf.

However, whilst looking for some gentle holiday reading, before last month's trip to Gower, I discovered 'Watching Birds' by James Fisher. This paperback book was a 1951 revised edition of the 1940s original and was a thoroughly absorbing read. As far as ornithological history is concerned, I have to admit that until recently I was a bit of a philistine. For instance, I was totally unaware of the significant role that Fisher played in shaping British natural history after the Second World War. This book, presumably purchased by my father in his twenties, wouldn't really be out of place today, though there's no mention of Collared Doves, who, in 1951, were still four years away from colonising Britain.

One particular paragraph brought a smile to my face. It was on the subject of geographical tally-lists, as a way of keeping records, but touched on a topic that's still hotly-debated in ornithological circles today.

Fisher writes,

"But the tally system does produce certain peculiar results. It tends to focus people's attention on the variety of birds they can see, and among a certain section of ornithologists it induces useless rivalry."

Ouch! That'll be twitchers then.

The next book I discovered was 'Life of a Scotch Naturalist' by Samuel Smiles, a seventh edition from 1879. This is a biography of Thomas Edward, a 19th Century shoemaker with a love and a talent for natural history. Despite a poor education and having to work long hours to support his wife and eleven children, Edward amassed several splendid collections in his lifetime. Sadly, they all had to be sold for a fraction of their worth to keep the family from falling into poverty. He was elected as an Associate of the Linnean Society in 1866 and later became the curator of Banff Museum.

However, on a personal level, the most amazing fact about this book, is that it belonged to my maternal great grandmother. On an inner leaf is a printed label bearing her name, above a short poem,

"If thou art borrowed by a friend,
Right welcome he shall be
To read, to study, not to lend,
But to return to me.

Not that imparted knowledge doth
Diminish learning's store;
But books, I find if often lent
Return to me no more.

Now slowly read, and often pause,
Think much; the book keep clean
And when returned to me, let not
The folded leaves be seen."

Who'd have thought it? There's a gene for pedantry!