Tuesday, 19 January 2016

Baffling Blue-tails

Going through my photos from the 'summer' now and tying any loose ends up. Which brings me to this pic of a female form of blue-tailed damselfly with a rusty orange thorax I hadn't seen before and didn't seem to appear in the field guides :

The mystery damsel
A striking individual with a rusty orange thorax and faint antehumeral stripe
Appears not to have a seg 8 tail light of any description
Not a great photo but I was straining over the fence just to get a shot
So needs to be sorted out properly. My Dragon ID 'bible', namely this one (published 1997) . . . .



. . . . states as we know, the female immature starts in two forms, either rufescens, with a pinkish thorax with faint antehumeral stripe and blue (seg. 8) tail-light, or violacea, with violet thorax and black antehumeral stripes and blue (seg. 8) tail-light. Fair enough, seem plenty of both of these forms :

immature form violecea

immature form rufescens


Both of those immature forms are little beauties, shame they have to change really. The development of the violacea can go one of two ways, maturing into either the infuscans form (green thorax with black antehumeral stripe and dull brownish tail light) or the typica form which resembles the male (bright blue thorax with black stripe, blue tail light). Here's a few I took earlier :

The only photo I can find of a mature typical form female
is this mating pair, where you can see quite clearly the female (left)
is exactly the same shade of bright blue as the male (right)

This photo shows an individual half-way between the immature violet form
and the mature bright blue form, she will eventually have a thorax
the same colour as the tail light.

This individual is again at a stage of development between
violet and mature but note the dulling of the tail light, I reckon
this individual will morph into the infuscans form
How to age the colours changes during development is something I don't know, but I have also encountered different shades of the infuscans form, it isn't easy but I'll have a go :

This dull form may be an early stage of development from the violacea

This individual seems to be getting close to the green of the
mature female infuscans shown in the books

This green individual photographed in shade is nearer the mark
Note the combination of the well defined black antehumeral stripe
and brownish tail-light, diagnostic of the infuscans form in whichever
stage of maturity 
It's the black antehumeral stripe which certainly means my mystery female is not a development of the violocea form as it has faint antehumeral stripes just slightly darker than the rest of the thorax, which leaves the rufescans form to look at.   
This form on the other hand, matures into only one type, the infuscans-obsoleta, with yellowish brown thorax, faint antehumeral stripe, and yellow-brown tail-light.
Or does it? because now there is a bit of a twist.

Fast forward to my European field guide  (published 2006) :



Which uses the same wonderful Lewington illustrations but the text by Odonata leading expert Klaas Douwe B Dijkstra refers to the different female forms as simply A, B, and C (where A=Typica, B=infuscans and C=infuscans-obsoleta, noting that B and C type females can become very dark when over-mature (a clue to my mystery girl perhaps).
Let's have a look :

This individual is on the turn from a rufescans, still showing
the pink thorax but the tail-light browning off nicely

This (apologies for crap photo) is an ovipositing female of the
mature infuscans-obsoleta form (type C) according to the books

Mystery girl is obviously of this form as told by the lack of
antehumeral stripes. The bolder colouring I conclude is due to ageing,
this must be quite an old individual and was indeed quite late in the season
when I found her. The tail light I presume also darkens with age which
is why it appears to be uniform with the rest of the abdomen.   

I think I've nailed it for definite, but the story keeps on throwing more confusion at me. Fast forward again to my latest acquisition (published 2014) :


This guide contains photographs of all the colour forms but the mature form of rufescens is referred to as rufescens-obsoleta rather than infuscans-obsoleta and shows a more orangey form of mature individual, now I'm more confused than ever, what's going on?
I look at the BDS website for clarity. Lo and behold, the home page has an item on the blue-tailed damsel which again refers to a rufescans-obsoleta form, so I look at the species account pages and find no mention of rufescans-obsoleta, but photographs labelled infuscans-obsoleta. (Hope you're keeping up with this :-O)
I then decide to use good old Google and I came across a scientific paper from 1999 which was aiming to standardize the names of the female colour forms and letting it be known that the form infuscans-obsoleta was to be known as rufescans-obsoleta, as simple as that :-)

So it seems that change has come into being and it looks like the BDS is complying with this but has yet to change the names on the species account.

So I conclude that my mystery individual will go down in the records as an over-mature form of rufescens-obsoleta (and certainly not as a boring old type-C female).
And what of infuscans-obsoleta? you may still see it being bandied about but I'm afraid it is now most definitely obsoleter ;-)

PS - By the way, the typica form can also be referred to as the andromorph form, just in case we need a bit more confusion.





Sunday, 10 January 2016

Changing Climate

As I've already stated numerous times, the summer of 2015 was awful for dragonflies (here in the north anyway), mainly down to the weather pattern for the whole year, not just the summer itself.

It's amazing to think that 2015 ended up as being one of the wettest years on record, considering we had hardly any rainfall in the first six months which led to usually shallow ponds being devoid of any water whatsoever when the first damsels and dragons should have been emerging, and this combined with the cold nights right through to July, would have the effect of either killing off many aquatic larvae or at least retarding their growth through lack of available food through abnormally cold water temperatures, with the cold water not being particularly conducive to emergence anyway.

Now I know one of the most consistent things about British weather is its inconsistency, no two consecutive summers are the same, so there's a good chance this year will be better altogether (fingers crossed), but what of the changing climate? It's well documented the world as a whole is changing, and whether you believe it to be man made or just the natural cycle there is no doubt the planet is heating up. So what does climate change actually mean for the future of our Dragons and Damsels?  
 
Well, as it happens I recently followed a link on Twitter which led to a scientific paper on the potential effect of climate change on British odonata, based on a study of records collated between 1980 and 2012.
Written by leading experts including Steve Cham and Dave Smallshire (who's Dragonfly book I just got at Christmas).



It was interesting reading (as is the book) with so many detailed factors taken into consideration but the conclusion was pretty much inconclusive, so no startling scare-mongering headlines on climate change for the Daily Mail to exploit (not that it would stop them).
 
Being a bit thick, I had to read it with the aid of a dictionary to semi-understand what they were on about but I did learn some new dragon-jargon in the way of science mumbo-jumbo, my favourites being :

Lentic – of standing water
Lotic – of running water
Phenological shift – A change in the time of growth and breeding of a species

Biotic homogenization- the process by which species invasions and extinctions increase the genetic, taxonomic or functional similarity of two or more locations over a specified time interval.

All good stuff, but here’s a summary of some of their findings in terms I can understand myself :

Of 36 British breeding species which were studied, 8 have significant negative distribution trends over the period, whereas 19 have been positive.
Before the study was made one of the things they expected to find was that species with longer flight periods would have greater ability to respond to environmental change as they have a greater opportunity for dispersal . . . . but this proved not to be the case.
They also expected to find that species which overwinter as larvae would suffer more than those which remain dormant as eggs, seeing as larvae can be washed away in floods to unsuitable habitat which will affect their development . This also proved not to be the case.

So what did they find? Well, they found that positive trending species (the biggest gainers being Emperor and migrant hawker) come about for two reasons. Climate warming has increased habitat suitability for those dragonflies with lower thermal tolerance, meaning southern species used to warmer climes will drift north. But the increased distribution of many species since the mid-2oth  century can be as much attributed to far improved water quality over the period due to the dismantling of heavy industry, mining and the introduction of environmental laws.
I remember as a lad there were pitheads visible in all directions as you travelled through the northeast and we used to play on the slagheaps which are now parks and nature reserves, so it stands to reason that dragonflies among other wildlife would benefit greatly from this and start to spread into previously uninhabited areas.


Red-veined Darter
I photographed this one as a migrant at Kibblesworth in 2006, With the change in climate they are become
established breeders in the south of England so how long before we see more of them oop north?
On the other hand there is a negative effect on those species with a northern bias, as they require more specific breeding habitat and due to the changing climate find they have to share their landscape with more species as a result of the northward charge of southern species. Moorland (common) Hawker and Black Darter being the two most noteworthy, though the decline of another two of the greatest losers over the period, scarce blue-tailed damselfly and common clubtail, are most likely to do with destruction of suitable habitat in their limited range rather than climate change.

Black Darter
Appears to be one of those species losing out, but a good year for them in Gateshead, with more noted
than ever before late in the season.

So there we have it. Though a large number of dragonfly species have increased their range in the UK between 1980 and 2012, it is as much a response to increased water quality as it is climate change.
Here in the North East we have a paltry number of species to look forward to each year so I'm all for a positive effect of colonisation due to climate change or whatever, but the long term forecast is as much a mystery as a whodunnit? with the last page missing, there are so many theories being bandied about. Some say our summers are going to get hotter, some say wetter, some say cooler and drier. Whatever the future holds, it's just as I said at the beginning, where our weather is concerned, the only certainty is the uncertainty. 
Here's to the next summer, and whatever it brings ;-)
   
And for anyone interested, here's a link to the actual paper I took the info from :

https://peerj.com/articles/1410/?td=tw



 

 

 

Wednesday, 6 January 2016

Review of the Dragonfly summer 2015 - Part 2 (of 2)

Into August thenand the awful weather continued to dominate the summer. This, combined with the school holidays and sadly a family bereavement, meant dragonfly days (indeed days out of any kind) were few and far between.
Early in the month (and before everything went pear-shaped) our annual family summer outing to Cragside provided the usual dragonfest at Slipper Tarn, once again a major highlight of the dragonfly summer, with Black Darters in abundance, including for the first time immature males, so a great result that :-)

We hit lucky with the weather today, as seen in the strong shadow being cast by this cracking male Black Darter
one of many on show at the Slipper Tarn.

But the stars for me were a handful of immature males, I'd never even seen one before
never mind photographed one.

Note the wavy lines along the flanks of the abdomen of the young male . . . .

. . . . compared with the straighter edges along the flanks of the female.

I spent the majority of August just snatching brief visits to Far Pasture when a bit of spare time allowed, which did get me some superb views of a female Southern Hawker at the top of the access road on the 4th, an area frequented by hawkers on most of my fleeting visits :





Perched low down, I could get some good angles on this
tired female Southern Hawker.

And on the 26th a male posed similarly in the same area :



Beautiful markings on the mature male Southern Hawker
Despite those two close encounters, my visits mainly showed low numbers of common darters, and similarly small numbers of damselflies, and despite a few treks up to Thornley Woods Pond where past years have provided spellbinding encounters with the southern hawkers, this year proved to be the worst ever, with just the odd patrolling male, and I never once witnessed the ovipositing of a female, in past years a guarantee and highlight of the calendar.

The valley was poor all round if I'm honest, but reports from Kibblesworth at least showed it had not lost any of its star billing, including stunning news on the 26th, when Ron Hindhaugh (Notmanywords) photographed a superb male Brown Hawker there in flight, a cracking find and a cracking set of photos too :

Brown Hawker (male)
Without doubt Gateshead's star dragon of 2015 - and first sighting of the species in over a decade
Sadly circumstances meant I still couldn't get over to Kibblesworth to try and see this beauty for myself, but I'm determined to get over next year and hopefully find another, we'll see ;-)

It was early September before I finally caught up with a Ruddy Darter at Far Pasture, a long time in coming (indeed I was beginning to wonder if it was coming at all), but worth the wait for this cracking little dragon, and a single male was seen numerous times during the month by the roadside :

Ruddy Darter (male)
These confiding little dragons are one of my favourites

Once they get used to your presence they are usually very approachable for close-ups
Note the extended black around the frons, black legs and a combination of rich rufous colours giving its name.

Southern and Migrant Hawkers were also thin on the ground for the most part, with a maximum of 4 Southern and 5 Migrants (including a pair in the mating wheel) seen on the same day at Far Pasture being the best count, though none remotely photographable. So if it hadn't been for the Ruddy encounters, September too would have been a non-event.

But we were due a bit of luck and lo and behold, the mildest autumn in years prolonged the dragonfly season beyond normal parameters and ensured some cracking late season entertainment. George Simpson had been keeping me informed of the build up of Migrant hawker numbers at Shibdon Pond, sending some lovely photos over, and when early October brought possibly the best spell of sunshine of the entire year, I spent a couple of afternoons up there trying to get some shots of my own, hard going on the first outing, but quite successfully on the second, and a bonus male Southern Hawker as well :

Migrant hawker (male)
My first visit to Shibdon didn't offer many photo opportunities despite a decent number present,
 this being the best of them
A similar pose started off the second session well, but it was hard going after that as feeding time
kept the hawkers airborne for long periods.

This male Southern Hawker was star of the show on my second visit,
I could see he was tiring so waited until he settled before closing in for photos.

And got some decent shots in the not so harsh autumn sunlight

Until a second male came along and the inevitable skirmish took him away :-(

Then I stumbled across this Migrant Hawker low in the reeds for best photos of the day of that species too. 

Again getting some cracking close-ups to end an entertaining session on a high.


Mild weather continued through late October into early November, and small numbers of Common Darters hanging on at Far Pasture gave me ample opportunity for some late season photos, one mating couple in particular allowed some superb close-ups :

This pair wouldn't budge even with a camera stuck in their faces, so I could focus on the male . . .

. . . . then shift focus to the female

And amazingly my latest ever record, with still a dozen Common Darters still present on November 10th, 6 days later than my previous latest sighting.

Common Darter at Far Pasture - one of a dozen still on November 10th
So a poor year at least ends with a new record
I'd heard during a cold spell that work had been going on at the Forbidden Pond, so I had a look on my last visit to the area and couldn't believe what I found :

Forbidden Pond :-O
The whole area had been basically removed. All surrounding vegetation taken away, and the pond had been
dredged to make it deeper, with a man-made bottom (like a massive garden pond) in place to stop the water
from draining away. Looks bad at the moment but hopefully it will be landscaped and be better in the long term 

So to summarise ; on the plus side, the melanotum form Large Red damselfly in the first month was my personal dragon of the year, though Ron's Brown Hawker was undoubtedly Gateshead's dragon of the year.
A new pond to keep tabs on at Far Pasture was a bonus, though I wish they'd kept the ponies out a while longer, and now it's a matter of wait and see with the reconstruction of the Forbidden Pond.

I enjoyed searching for demoiselles in the valley, and early season chasers and late season darters and hawkers were all good sessions, it was just the middle bit (the actual summer) which was a major let-down.
My species count of 14 was the poorest since I began this blog 5 years ago, I only got out of the valley twice over the summer which didn't help in that respect, was gutted not to get to Kibblesworth at least once, and didn't even get a proper day out at Gibside, which is just over the road and always good for a dragonhunt at the height of summer.

This of course was mainly due to the weather, which had a knock-on effect from very early on. The long winter, the short cool spring and finally the basically shit summer had a drastic effect on the state of ponds and early season damselflies which I've never known to be in such sparse numbers. Only the Indian Summer (to mid Autumn) saved the season from total disaster, Shibdon Pond providing the best sessions late on.
Of my local patches, Thornley Woods Pond was disappointing for the second year running with hardly a hawker to be seen, and is beginning to look really overgrown since it was opened up three years back.
Far Pasture had all the usual suspects, bonus four-spot chasers, but disappointing numbers-wise especially damsels.

All in all I have to say 2015 was poor in so many respects, but still with some cracking memories.
I'm already looking forward to seeing that first pale damselfly fluttering up out of the grass on milky wings come early May, so bring on 2016, when I'm sure the disappointments of last year will soon be just distant memories. Thanks for reading, and for all your comments and sharing of sightings over the year, much appreciated :-)

Tuesday, 5 January 2016

Review of the Dragonfly Summer 2015 - Part I (of 2)

A big (if belated) Happy New Year to all my readers and fellow Odo-enthusiasts, time for a review of last Dragonfly season, though 2015 was by no means the best on record (large dose of understatement to start).

Have to say I was looking forward to the 2015 season, being armed with my new Fuji X-S1 camera (after losing my Panasonic lumix last year in the Stargategate incident) and ultra close-focussing Pentax Papilio binoculars for viewing dragons in supermacrovision, I couldn't wait to get started.

But wait I did, the winter, though not particularly harsh, dragged on through early spring, resulting in a particularly cold but dry April, resulting in delayed emergence, and when the sunshine finally arrived in May it didn't hang around for long.

I found my first teneral Azure damsel at Far Pasture on May 8th which was as pleasing as it was surprising, and numbers increased slowly during the month, but May consisted of mainly cool, dry weather, meaning reports from elsewhere were all negative, and shallow ponds throughout the borough were left bone dry by the prolonged lack of rainfall, again affecting emergence and numbers.

First dragon of 2015
Teneral female Azure damsel @ Far Pasture
Only very late in the month when the sun appeared again did I find my second species, a teneral Large Red damsel at Thornley Woods Pond, after numerous disappointing visits for this usually early emerging species, so a very slow start indeed. But May ended with a cracking highlight when I found a melanotum form female Large Red damsel at Gibside Lily Pond on the 30th, my first ever of this rare form, and just reward for scrutinising or photographing every individual possible for the last five years :-)


Large Red damsel (Gibside Lily Pond)
Female of the rare melanotum form, whereby each abdominal segment contains a large percentage of black
(rather than red), and is the only form which retains the yellow antehumeral stripes (braces) when mature.
 
June was different altogether, as our first period of warm and sunny weather continued, and the early dragonflies at least burst forth with a vengeance.

A maximum of seven Broad-bodied Chasers at Far Pasture Forbidden Pond in early June was a best ever count, though my attempts at photographing them were poor.

Male Broad-bodied Chaser
Very difficult to get a pic from a decent angle at the Forbidden Pond, and a good number present meant
skirmishing took up most of their attention, never posing long enough for an approach.
And then a tip-off about the previously unvisited pond in the next field came up trumps for Four-spotted Chasers, with a maximum of five seen on frequent visits to the end of the month. A lovely pond this which on occasions was teeming with Azure damselflies for certainly the best damsel count of the summer (and another 4 species present in smaller numbers) so I don't know how it's escaped my attention these last few years.

Far Pasture 'Ponyfield Pond' A hidden gem in the valley

Four-spotted Chasers repeatedly came to provided perches offering superb photo opportunities

Beautiful wing markings of this male in his prime

A trip along the river to Haghill on the 11th resulted in an excellent count of 13 Banded Demoiselles, including one which captured a Mayfly and landed beside me on the path to devour its meal.

Opportunity missed
Banded Demoiselle afforded an unbelievable opportunity for photos as it devoured its meal on the path beside me,
but despite reeling off over 40 snaps I was unable to get one in perfect focus, as I was still struggling
with the settings of the X-S1 in the early season.
Unfortunately, after an excellent first two weeks of the month, the rest of June was back to cool and cloudy weather with hardly a dragon to be seen, resulting in very poor counts for damselflies all round.
Into July and again the early part of the month was by far the most conducive to dragonhunting. A return to the 'Ponyfield Pond' at Far Pasture gave me some cracking photos of a Four-spotted Chaser at last, and a trip along the banks of the Derwent for Banded Demoiselles paid dividend with some superb close-up views and decent photos as well.

A superbly poised Four-spotted Chaser, a new alpha male taking the most prominent perch on the pond.

Love this snap of the same male, he appears to be having a right laugh.
Male demoiselle in the meadow on the banks of Clockburn Lake, unexpected but super views. 

This male gave even better views through the Papilios on the bank of the river,
gorgeous metallic sheens in the sunshine, and superb wing patches on this prime specimen
Thornley Woods Pond was still disappointing but 6-8 exuvia found early month and an emerging female Southern Hawker was the only one I would see this year.

Southern hawker exuvia, one of 8 found in total

Female Southern Hawker emerging
I missed her maiden flight after spending almost an hour watching I took a five-minute wander
and she'd gone on my return, sod's law strikes again.

On one visit I spotted what I thought was a drowned male Southern Hawker in the pond which made a quite captivating if tragic image, but he began moving so I fished him out and left him to dry.

Tragedy and beauty in one image, immature male Southern Hawker apparently drowned.
 
But not so, he started twitching so I fished him out and hung him on a bracken frond in the sun.

Which is where I left him to dry out, and only hope he recovered to live out his second chance.
The remainder of July was again poor. I didn't manage my annual pilgrimage to Gateshead's flagship dragonfly site, namely Kibblesworth Brickworks Pools as I couldn't synchronise a day off with good weather so missed out on Black-tailed Skimmer and Emperor there, though they were both reported in decent numbers through the month.
Also the ponies were back in the field at far Pasture, preventing me from checking on that lovely pond again for the duration of the summer :-(

By the end of the month the last of the damsels, the Emerald, was on the wing but not in any great numbers and photo opportunities were few and far between, and Common Darters were also beginning to show, though in disappointingly small numbers too.

I caught a decent emerging day at Gibside Lily pond mid-month, and captured some decent images
on a brief visit during a family day out. This immature Female Emerald was best of the bunch.
 

Or was it this one? for once I managed to get the whole insect in decent focus,
must be getting better (or just lucky) 

An arty shot of a Common Darter, taken between gaps in vegetation but a nice composition.
 By now of course I had the school holidays to contend with as well, would the second half of the season be any better than the first? Find out in part two of my season's review, coming up shortly. Cheers :-)