Local Med Gull.

Gull flocks on freshly ploughed fields are always worth a look at this time of year. Several hundred gulls had gathered adjacent to the main Sawbo-Stortford A road so I went through them from a safe distance. They are always on the move as the tractor goes to and fro, and this lot spent quite a time over the horizon, all of which is just an excuse for saying I might have missed quite a lot.

Hundreds of Black-headed Gulls, lots of Lesser Black-Backed Gulls, low tens of Herring Gulls including a couple that generously dangled their legs in flight showing them to be Yellow-Legged Gulls. about 10 Common Gulls and one juvenile Mediterranean Gull.

Local birder Alan has some fantastic shots of juvenile Med Gull from Rye Meads on his blog. This may have been the same bird. My photos are inevitably nowhere near as good, but I like to think give a flavour of the reality of scanning through a distant flock. It is in focus - honest. It's just the heat haze giving it that blurred look.

Dipping at Minsmere

Baird's or Broad Billed? both 2 hrs in the car and about 100 miles. In the end, the Baird's at Minsmere has it because Minsmere is a top quality nature location and Frampton Marsh RSPB (Broad-Billed)  looks to me like a shed in a muddy field.

The Baird's had gone, along with all the more interesting waders. There were still Spotted Redshank, but not whilst I was there, and a Honey Buzzard flew over, but I was elsewhere at the time, and there was a Stone Curlew in the field but I missed it. I missed so much I'm not sure I went to Minsmere at all. Maybe I ended up at a nearby country park by mistake.

There was other stuff though, particularly the famous Beewolves. These are solitary wasps, although given the numbers that may be a bit of a misnomer. I guess 'solitary' refers to the fact that they don't form communal nests but instead each has their own burrow. They dig about a metre down, have 4 or 5 nest chambers, lay eggs and then feed the larvae on bees they paralyse and drag down the holes. Brutal. Here's some pictures.

with paralysed bee

... and into the larder it goes.

There were a few Grayling butterflies on the beach. As soon as they land they show a bit of a brown fore-wing underside with orange flash and eye, then retract it. Here's one in typical pose.

Up to Whin hill. At the top there were meant to be silver-studded blues. I saw only brown ones that looked like Brown Argus, and when I got home and looked in Tomlinson that's exactly what they were. Check the flash on the lower underwing.

There was lots of an attractive pink -thyme like plant, which may be Wild Thyme or may be Marjoram. I'm not sure.

And lots of this bumble bee. The elongated abdomen with extensive white tail is quite distinctive.  I think it may be Garden Bumblebee as this says they have a distinctive long appearance which these have. But it doesn't have the lower band on the thorax ... hard work sorting out these bumble bees.

What's that bird #2 - Hatfield Forest.

another one in a series of birding fiascos. Returning to the car at Hatfield Forest I heard a song I couldn't quite place. Blackcap? Song Thrush? If it's one of those two why am I not sure what it is? Out comes the phone and here's another very crap recording. All the action is in the last 10 seconds.

On getting home I went on to Xeno Canto and after some searching and got a match. Icterine Warbler! So that's another occasion when I could have made a decent recording, even seen the bird, and didn't.

I've been back twice since then, and today on the second trip found a bird giving pretty much the same song at the same place. Here's a second, better recording.

Finally I located the bush the song was coming from, saw a twitch in the leaves, and there it was, a ...  well the answer is at the bottom of this post.

I've spent a few hours in the Forest as you can imagine, and apart from the usual woodland birds (Nuthatch, Garden Warbler, Great-Spotted Woodpecker, Buzzard), saw Spotted Flycatcher - three minimum with at least one juvenile, and also a couple of Marsh Tits. I saw two female Purple Emperors, 7 Silver Washed Fritillaries, and some Purple Hairstreaks. I've finally got my eye in on the Hairstreake; there are often Ringlets in the higher branches of trees, but these have a leisurely flight. Hairstreaks are smaller and whizz around like mad things. I eventually got a distant picture, which is shown much blown up and cropped here.

Purple Emperor Female

Purple Emperor opening its wings. 

Purple Hairstreak

Spotted Flycatcher

Great Spotted Woodpeckers having a disagreement

Purple Emperor sunbathing

Oh and the mystery bird? Blackcap! I know. I'm pretty sure that was the bird that was singing. I'm still reeling.

Hatfield Forest Emperors

Purple Emperors have been found in Hatfield Forest in the last few years, so I went up (again) to try and find them.

I eventually found a master tree up a broad ride going NW from the Forest Lodge area, up toward Beggars Hall Coppice. the master tree had the key signs, an oak tree taller than the surrounding trees, and two likely-looking people stood looking up into it. Before long we saw a female come down towards eye level, and as our eye got in we saw two more butterflies flying at the top of the tree, presumably males.

I did wonder whether the female was a White Admiral, but fortunately someone else there knew what they were doing, and saw the key eye-spot underneath. Here's some dodgy photos, much cropped and expanded.

some more butterflies

Small Skipper?

Silver washed Fritillary

Longhorn Beetle

Master tree straight ahead.

More insects and stuff.

various trips to various places. Finding out that insects are in their own way every bit as hard to find and identify as birds. who knew? 

 A visit to Canvey Wick , a buglife reserve in West Canvey, an old oil container site now left to go wild for plants and most significantly bees. I went hoping to see the rare Shrill Carder Bee. There were quite a few bees but only one that fitted the bill. I was quite happy at the time it was a Shrill Carder Bee but on getting home and comparing the photo to the book I can't see any reason why it isn't just a Common Carder Bee queen. No obvious orange tail (although I thought at the time it had one) or brown band. And as digital photography is now the only acceptable evidence of sightings then this one just has to pass unidentified.

No idea what this is ... not a corn cockle as it has a very different thick-leaved plant structure.

A Darter. It seems to have black legs so is a female Ruddy Darter?

Not sure where I saw this one, but it looks like a brown-form female Common Blue Damselfly so is really very common.

Hatfield Forest Wall Wood in a desperate hunt for decent butterflies, but came away empty handed. A nice Fallow Deer, and what I thought was a Hornet on close inception was clearly not one - the head was all wrong. I think it is Volucella Zonaria, the Belted Hoverfly. Scarce up to the 1940's, now quite common in the south.

A visit to Portland Bill in bright sunshine with some cloud. Some spectacular colours ...

At this time of year the Lulworth Skipper is a significant local species and with some guidance from the jobs I located one in the field between the jobs and The Pulpit. The main id feature seems to be its monumental dullness. Plain brown. None of that flashy bright-orange seen in other skippers.

Lulworth Skipper

more flashy Small Skipper

lots of dense webs in the brambles, all with tubes with a spider sat at the base.

a number of these post flowering ... an alum of some sort?

Anyone lost some bees?

I have some spare ones in my garden...

The science of Greenhouse gases – The physics is simple

The physics of greenhouse gases is well known. The sun radiates energy, mainly in the visible spectrum, which falls on earth. The earth radiates it back, but because it is cooler than the sun it is radiated back at a lower frequency in the infra-red spectrum. Some gases, (mainly ones that are not diatomic) absorb this radiation so reducing its radiation back into space. Without these gases the earth would be colder than it is with much larger day/night temperature variation. Increasing the amount of these gases should increase the temperature of the earth. For an excellent account see [1]

A table of greenhouse gases generated by human economic activity is shown below[2]. The main ones are Carbon dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O). There are then a whole raft of CFC’s and other entirely non-natural gases which occur in trace amounts but are highly greenhouse-causing shown below. I have included just one(CCl2F2) The table has a column of “warming potential (100year)”. This is the contribution to global warming from a molecule of gas over 100 years based against that of carbon dioxide. For carbon dioxide and nitrous oxide these do not break down by themselves, but methane reacts with ozone to create water vapour and carbon dioxide, so over time will disappear. The warming effect of a molecule of methane is, by itself, higher than the 21 shown here.

Gas	Pre industrial levels ppmv	2011 levels	warming potential (100yr)
Carbon Dioxide	278	391	1
Methane	0.7	1.803	21
Nitrous Oxide	0.275	0.324	264
CFC-12	0	0.00053	10800

So the basic physics is indeed simple. We have generated greenhouse gases which have gone into the atmosphere and have resulted in the previous balance of energy being disrupted, and the earth is slowly heating up as we have seen in the previous posts.

Science is about numbers, and a key number in the science of global warming is the Climate Change Sensitivity. This is “broadly defined as the equilibrium global mean surface temperature change following a doubling of atmospheric carbon dioxide concentration”[3]. There is considerable dispute as to what this number is, for instance a widely quoted letter to Nature in 2004 [] states “We estimate a probability density function for the sensitivity of climate to a doubling of atmospheric carbon dioxide levels, and obtain a 5–95 per cent probability range of 2.4–5.4 °C.”. Well for something where the physics is simple, that’s an enormous range, and the reasons for this range illustrate many of the difficulties at the heart of the science of climate change and the debate about global warming.

The reason for the range is primarily around the changes in the concentration of water vapour which is a greenhouse gas, and the extent to which consequent changes impact the temperature. It is not clear how much additional water vapour will be present in the atmosphere due to warming, or how much the reflection back of light from clouds offsets the additional warming.

One aspect of warming is that temperature change is not equally distributed. The loss of ice, for instance increases warming in arctic regions. This can be seen most clearly in the chart shown below [4] which shows the UK as having a 2C increase in temperature but the high arctic having an increase of over 4C. Here Antarctica is not warming, but Antarctica is different – it is surrounded by sea which acts as a means of drawing heat away from Antarctica. Some use the lack of warming or melting in Antarctica as a piece of contrary evidence for warming taking place, but there is no basis for thinking that everywhere warms at the same pace, so that criticism is not a valid one.  One feature is a blue blob south of Greenland – this is believed to be due to melting ice producing a flow of cold water into the north atlantic, so is no source of comfort.

Reflection back of sunlight is one of the main contributors to determining whether and how much the earth warms. Events such as volcanoes, or even forest fires, can increase the aerosol effect [5], whereby particles in the atmosphere reflect back light, and so reduce the heating effect of greenhouse gases. Melting of glaciers, snow, and ice also decreases reflection back of sunlight. Climate changes often have offsetting effects, so the increased greening of arctic regions due to warming and ice-melt has the effect of lowering warming due to increased absorbtion of carbon dioxide by plants, and of increasing warming due to loss of reflectivity. It seems that losing snow and gaining plants is generally warming is the loss in reflection outweighs the reduction in carbon dioxide.

There are a range of feedback effects that occur, some positive and some negative. Increased carbon dioxide increases temperature which increases the amount of water vapour that increase the greenhouse effect that increases the carbon dioxide in the atmosphere, and ice and snow melt reducing the reflection of light back to space increasing the greenhouse effect. There is a clear difficulty in evaluating theories where an input can become its own output, so Climate science uses the term “forcing variable” to identify which quantity is being independently changed.

Others have a different explanation for the changes in gases we see today.  There are well established relationships between temperature and the concentration of certain gases in the atmosphere. As temperature increases, carbon dioxide levels increase. Some people believe that we are in a warming cycle, hence global temperature rises and the equilibrium concentration of carbon dioxide in the atmosphere increases. We are generating carbon dioxide  and the concentration of carbon dioxide is going up, but that is just coincidence not causation. I will be returning to this in a later post.

Next post I will look at some of the history of global temperature and composition of the atmosphere and try and see how this informs the current debate.

1. http://www.sandia.gov/~jytsao/physics_global_warming_2008_04_notes.pdf

2. “Climate change, a very short introduction” Mark Maslin

3. https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-6.html

4.http://assets.climatecentral.org/images/made/2_16_16_Brian_NASAJan2016Temp_720_465_s_c1_c_c.png

5. http://www.metoffice.gov.uk/climate-change/guide/science/explained/aerosols

Update. So that bit about the pacific ocean cycles causing the hiatus post 1998? turns out it might have been the aerosol effect from burning fossil fuels  (http://www.skepticalscience.com/aerosols-key-to-slowdown.html). Or not.

Insect Interlude

With hay-fever rampant and birds getting on with raising young, its local visits for insect life for me at the moment, mainly with my new macro lens.

Usual disclaimers on photographic incompetence apply. If you want really top quality insect photographs I recommend Marc Heath.

Here's some from the patch

Marbled White hiding behind an annoying blade of grass. 5 of these seen today - don't think i saw one last year.

Cinnabar Moth

Small Skipper, orange antennae distinguish this from EssexSkipper.

Not my best, but I think from the complexity of the markings on the wings this is Large Skipper.

Ringlet. Quite widespread and numerous.

The yellow on the top of the thorax identify this as a male Red-Tailed Bumblebee (Bombus Lapidarius), What a fantastic bee!

A common one, either Garden Bumblebee (Bombus Hortorum) or Large Garden Bumblebee (Bombus Ruderatus)

One of the benefits of being an idle and clueless gardener is that the forest of unkempt plants does attract a few insects.

This is black bean aphid as found in all the best untended gardens. If you look carefully you can see ants too. Here's the explanation for their presence courtesy of wikipedia: "Ants climb the host plants and feed on the honeydew secreted by the aphids. Many species of ants have developed behaviours to enable them to protect and encourage their aphids. Black garden ants (Lasius niger), for example, remove predators such as ladybirds from the vicinity of aphids, thus keeping their "milch cows" safe."

A plug for a fantastic book "A Buzz in the Meadow" by Dave Goulson, in which he observes that the aphids usually reproduce by parthenogenesis, i.e. the females produce more genetically identical females, but toward the end of the year some grow wings (you can see some winged ones in the picture). These winged ones fly off and reproduce sexually. The ants don't like this so tear the wings off some aphids. It is just great to see this kind of drama being played out in your own garden

A second too late as a bumblebee flies off. The dark tan head, black body and white tail show this is a female Tree Bumblebee (Bombus Hypnorum). Appropriately in the midst of a series of posts on global warming,  the Tree Bumblebee was unknown in the UK before 2000, but has expanded its range north and is now common and widespread throughout southern England.

I Interrupted a Common Garden Spider having its lunch.