Monday, 20 August 2018

Gravel puss and a solicitous damsel

Following the post where I was extolling the virtues of Wild Radish, I turned to more mundane matters and decided to tidy my van ready for the working week. The Satmobile has a hard life, lugging all manner of equipment to various points of the Orcadian compass, often in foul weather, so it was due a bit of TLC.

After vacuuming the cab, I bent down to coil up Henry's power cord and came face to face with this...

 A Puss Moth caterpillar, somewhat out of its comfort zone, in the middle of the gravel hard standing where we park our vehicles. How it came to be there, I know not, but after watching it for a few minutes, it became obvious that the caterpillar was trying to spin a cocoon.

We removed it to a place of comparative safety amongst the potted trees and shrubs tucked in by the garage wall, and left it to decide its own fate without becoming accidentally squished.

In the late afternoon, the sun eventually put in an appearance, so we drove down to Hoxa Head in South Ronaldsay to look for dragons and damsels at the pools there. Sadly, these were drier than my previous visit, with nary an ode in sight. Checking the old quarry nearby, we did manage to find six Blue-tailed Damselflies, including this bromance between two males.

The flight season in Orkney for this species has now passed its peak, so breeding opportunities will become ever more rare as numbers inevitably decrease. Some males struggle with this concept and will try to mate with females of a different species or, as in this case, with a male of the same species.

The lower male is showing his disgruntlement by flashing and flaring his wings at the other damselfly, which is as about as angry a sign as these insects can muster. For the record, mixed pairings, either of species or gender, are destined to be unsuccessful.

Sunday, 19 August 2018

It's a jungle out there

Having had the good fortune to finally identify, after four years, the Mystery Brassica growing in our garden (all we'd needed to do was attend a field trip to look at arable weeds), I thought I would re-iterate why we tolerate Wild Radish springing up randomly within our environs. In a nutshell, or more accurately in a seed pod, the local wildlife loves it.

All manner of insects flock to the flowers: several butterfly species (Green-veined and Large Whites); moths (Silver Y); and all manner of hoverflies, to name but a few. The Large Whites lay eggs on the brassica as the leaves are the food of choice for their caterpillars.

At this time of year, Greenfinches, which have been strangely absent for the rest of the year, suddenly appear to chomp their way through the Wild Radish pods, leaving the ground beneath the plants covered in a neat layer of evenly-sized remains.

Also at this time, the Large White caterpillars set off to find a safe place to pupate, often making quite a journey, as we usually find some on the walls of the house.

Quite whether the effort is worth it is debatable, as most seem to parasitised by a small wasp, whose own larvae emerge from the caterpillars to pupate themselves. Local bug guru LJ reckons these might be from the wasp Cotesia glomerata.

And here, below, is the remains of a past parasitisation with, alongside it, a recently-arrived Large White caterpillar preparing to pupate. It doesn't bode well, does it?

Still, every year, there are Wild Radish plants aplenty, a host of Large White butterflies, several Greenfinches and, apparently, parasitic wasps, so some sort of order is being successfully, if chaotically, maintained.

Interestingly, whilst Large Whites will feed on many types of brassicas, the Wild Radish is actually the favoured food plant of the Green-veined White. As mentioned above, we see these regularly in the garden, but I can't recall ever finding their caterpillars. Must try harder!

Wednesday, 15 August 2018

Stuff On My Phone (19)

It's been a while since the last SOMP post, and as other posts aren't exactly queueing up to splurge all over the blogosphere, here's my latest offering.

Last time out, there was a rather scientific slant to the whole thing, what with Professor Brian Cox explaining the creation of the elements within the life cycle of stars. This had me pondering some other scientists and science facts which have been included in popular music culture...

Within the lexicon that is the Tense Towers vinyl and CD collection, there loiters the 1976 Vangelis album, Albedo 0.39, named after the Earth's reflecting ability (39%). The eponymous and final track on the album features Vangelis (I presume) reading out all manner of Earth-centric scientific facts, culminating in the afore-mentioned Albedo 0.39.

In the 80s, of course, there was Dr Magnus Pyke, who featured in the Thomas Dolby hit, She Blinded Me With Science, all waving arms and booming voice.

Perhaps most famously, a sample of the voice of Professor Stephen Hawking was used on Keep Talking from Pink Floyd's 1994 The Division Bell album, having been previously used in a British Telecom television commercial.

However, the subject of this particular SOMP piece is a track found on Combination Head's 2008 album, Progress? Now, Combination Head, a band created by prog keyboard maestro Paul Birchall, aren't particularly famous, in fact, I had to send off to cdbaby in America for their first album, as it wasn't available in the UK at the time. Weirdly, some years later, I received an email to my personal address inviting me to add the sender to my LinkedIn contacts. This was a bit freaky, as LinkedIn don't operate like that, but when I realised who the sender was, it all made sense... Paul Birchall! So here's the track, it's Solid Ground and as well as some good old progressive rock keyboards, it features a few salient facts about the constitution of matter, read out by Lyn Christine (it says in the album notes).

Sunday, 12 August 2018

Welcome to I&Tplayer...

Blogging at Tense Towers just hasn't been happening of late, so time to catch up on what you've missed with a rapid round-up of recent romps.

At the end of July, First Born visited for a long weekend of food and frolics...

Ensconced in the Teashop in Stromness 

Watching Puffins at the Brough of Birsay

Our Lass and First Born pose for a sunny selfie

As she left, First Born managed to photograph Tense Towers from the plane!

On the 6th August, the Orkney Field Club organised a trip to Flotta, ostensibly to look for the presence of Emerald Damselfly in a bid to explain the recent spread of the species to Hoxa Head in South Ronaldsay. To break out from the population in Hoy, the Emeralds would likely have needed to travel across Flotta, so if we found any, it would add credence to this theory. An excellent day of general wildlife watching was had, especially as the first damselfly seen was an Emerald!

A fence post with a wig of lichen

Stanger Head, looking across to Switha, Cantick Head and the Scottish mainland

Kirk Bay, Flotta

Yours Truly participating in a bit of a spontaneous beach clean. The huge beach ball seen at the bottom of this cliff had likely come from a passing cruise ship or been blown across the Pentland Firth from the Scottish mainland. Photo courtesy of AG.
On the evening of the 8th August, the Flora sub-group of the Field Club met at a farm to learn about arable weeds. In many places these plants have been wiped out due to the excessive use of herbicides in an attempt to produce monocultures of specific crops.

Fumitories. There are six species in Orkney, two of which can be seen here.

Treacle Mustard

Annual Nettle, the much more potent cousin of the Common Nettle
Then, yesterday, Our Lass and I took a trip to Hoy in the hope of seeing the recently-fledged White-tailed Eagle chicks, the first brood to be successfully raised in Orkney for 145 years.

Looking across to the hillside of the Dwarfie Hamars, where the eagles had nested.

RSPB volunteers were on hand to help visitors spot the birds.

There are two young eagles in this shot, one on a mound towards the bottom left, and the other in a similar position top right.

A male Black Darter basking on a bridge parapet.

A pair of Common Hawkers making out.

A Black Darter perched on my camera lens (Pet, give us your camera quick!)

 And that's us up to date. Phew.

Tuesday, 24 July 2018

National Dragonfly Week 2018

As alluded to in the previous post, Saturday 21st July saw the beginning of 2018's National Dragonfly Week, as decreed by the British Dragonfly Society. Locally, I ran an event under the auspices of the Orkney Field Club, promoted through the Club's web page and Facebook site, as well as on the Odonata-centric OrkOdo page.

Nine hardy souls braved the early morning wind and rain to meet at the ferry terminal at Lyness in Hoy, for a gentle amble up to some bog pools on the southern side of Wee Fea. The eight folk who joined me varied in dragonfly experience, but they each brought plenty of enthusiasm for all wildlife, so prospects were reasonable for a good day.

The initial climb was quite sheltered, but two miles later, as we neared the first pools, a westerly wind was beginning to make its presence felt. In the absence of any direct sunshine, there weren't any dragons or damsels on the wing, so we began to search for roosting individuals amongst the rushes at the pool edges.

The group soon spotted a few Emerald, Large Red and Common Blue Damselflies, and began photographing the more approachable insects, a task made trickier by the afore-mentioned breeze.

Photo courtesy of MT
As I was explaining a few details of the life cycle of dragonflies, JT made the discovery of the day (ok, I called it early, but I was correct) by finding a recently-emerged Common Hawker dragonfly. Reasoning that it had not yet moved far from its emergence site, I was able to spot its exuvia, the shed larval skin, the only remnant left of the insect's several years spent as an aquatic creature. Although we didn't see any more Common Hawkers on the day, we did find six exuviae, proving that the species was breeding at these pools.

Photo courtesy of JT

As the clouds thinned and the temperature rose, a few Black Darters flew by, most of which were yellow and looked as though they had only recently emerged. However, the occasional mature individual was seen, including this male which actually became too hot in the brief spell of warm sunshine. It began 'obelisking', pointing its abdomen towards the sun, effectively limiting the surface area of its body able to absorb heat from the sun.

After a picnic lunch, we began the return descent back down the hill. The second site for the day was a larger bog pool which was located in a more sheltered location in the lea of the hill. For this reason, there were many more insects present, with butterflies, moths, bees and hoverflies all vying for our attention. But perhaps the most intriguing find was a Marsh Speedwell, a small plant with the characteristic blue Speedwell flower, but with leaves more akin to a Willowherb.

This site was predominantly populated by Black Darter and Emerald Damselflies.

The female damselfly above was in tandem with a male, but she didn't seem the slightest bit interested in mating with him, resolutely refusing to take their relationship to the next stage. However, she was having to be very patient, because until the male became bored and released her, she was rather stuck.

Here's a happier shot, of a pair of Emerald Damselflies ovipositing. Well, actually, it's obviously the female who's egg laying, but her partner is guarding her from other suitors.

Photo courtesy of PM
Another floral note at this site was a rather picturesque aquatic plant, Least Bur-reed Sparganium natans, many thanks to JC for the ID.

Our last target water body for the day was a pool beside the Scapa Flow Visitor Centre. This pool is less acidic, much more duck-infested, but blessed with pond weed and plenty of emergent vegetation. As well as more Emerald and Large Red Damselflies, we found several Blue-tailed Damselflies to take our species tally for the day to six.

Friday, 20 July 2018

Parched panic and possible precipitation

This weekend sees the beginning of National Dragonfly Week which, for 2018, runs from 21st to 29th July. What do you mean you haven't written it in bold pen on your calendar? Nor underlined it twice? Nor added exclamation marks? Just me then.

After 2017's full-on odofest around the islands, I decided to back off the gas this year, with maybe just a few events during the weekends. As it turns out, that's now seeming a bit ambitious, so there's only going to be one dragonfly walk, on Hoy.

What with all the hot weather in the UK, and Orkney hasn't been immune to it either, I began to worry that maybe the usual pools we visit on Wee Fea may have suffered from the lack of rain. To ease my concerns, I decided to carry out a recce, just to make sure we weren't going to be faced with vistas of baked mud and forlorn vegetation.

A previous graduate of the School of Odo, M, offered to help with the recce so, after consulting the weather forecast, we chose last Tuesday as a suitable time, close enough to be relevant, but space to plan (well, panic) for a new venue if needs be.

To refresh our collective memory, here's what the various pools usually look like at this time of  year:

And here's what we found on Tuesday:

However, and I don't fully understand the reasons behind it, there were good numbers of dragons and damsels to be found. In fact, the first ode we saw was a Common Hawker, silhouetted against the sky as we climbed to the higher pools. At one point, we witnessed three Common Hawkers at once, all males hoping to find a mate. I am guessing that perhaps many bog pools have dried up, so the remaining water is concentrating the population. For now.

Between pools, we wandered through a conifer plantation, listening for bird calls. Neither of us recognised the first one we heard as it made its way, unseen, through the treetops above us. We suspected a Crossbill, but couldn't be sure. We were more confident of the high-pitched calls of Goldcrest, and eventually were rewarded with views of this tiny bird. Then, in a clearing, I was amazed to encounter two Common Hawkers foraging, one even taking a butterfly on the wing.

At the lower pool, we stumbled upon what must have been a recent mass emergence of Emerald Damselflies, just too many to count. Again, perhaps the drying of the pool has forced their hand?

In all, we found six species, which is normal for these water bodies, although the distribution was different from previous years. We couldn't find any Blue-tailed Damselflies at the upper or lower pools, only recording them at the museum pool near the pier. The lower pool only produced Emerald Damselflies and a few Black Darters, so all I can really say is that this year is different. There has been a little rain overnight, so let's see what Saturday brings for the official Dragonfly Walk, hosted by the Orkney Field Club and OrkOdo.

My grateful thanks to M for her invaluable help.