Tag Archives: yellow dung fly

The life of a Yellow Dung-fly

05 Tuesday Sep 2017

Posted by in Insects, Nature, Nature of Wales, Wildlife of the Wales Coast Path

≈ 12 Comments

Tags

, , , ,

This post is possibly not one for the squeamish, but lately I’ve become more aware of these bright little flies and given thought to the vital role they and their kind play in maintaining balance in our environment, so decided it was time to learn more about them. Yellow dung-flies are one of the most familiar and abundant flies here in the United Kingdom and indeed throughout much of the Northern Hemisphere. They are out and about from March to November and at their peak in the summer. Anyone that walks in the countryside, particularly in areas where there are large mammals will undoubtedly have seen them. They may look a little fearsome close up, but are harmless to us, they do not sting or bite people or other animals!

Common Yellow dung-fly or Golden dung-fly – Scathophaga stercoraria

Yellow -dung-fly male

As its common name suggests, the life of a Yellow dung-fly, particularly that of the males is centred on, yes you’ve guessed it … dung! They spend most of their lives either upon it, or looking for it. They favour cow pats, but are adaptable and will settle for the dung of other large mammals such as horses, deer or wild boar if that’s what’s available. Unsurprisingly here in Wales they mostly have to settle for that of sheep.

 

Male and female yellow dung-flies

Dung-flies belong to the Scathophagidae family of flies which are integral within the animal kingdom in the role of  assisting in the process of the natural decomposition of dung in fields and grasslands. 

Description: 5-11mm long. Average lifespan is 1-2 months. Sexually dimorphic, males are golden-yellow with orange-yellow fur on their front legs and are larger than the females. Females are generally duller in appearance, more of a green-brown colour and have no brightly coloured fur on their front legs.

Behaviour 

Males and females are attracted to fresh dung by its scent and actually approach deposits flying into the wind. Males spend most of their time on the dung waiting for females to mate with and being predatory insects, sometimes feeding on other insects that visit the dung, such as blow flies. Females on the other hand spend most of their time foraging in vegetation and only visit dung to mate and subsequently deposit her eggs.

Reproduction 

Rival male dive-bombing a mating pair

The male-female ratio of flies on a dung pat is typically heavily biased towards males. Often several males can be seen waiting for a female to arrive, so if and when one does, competition to mate is high: the smaller, outnumbered females don’t have much say in choosing their mate.

The act of copulation lasts 20 to 50 minutes during which the couple may be subject to aerial attacks from rival males attempting to dislodge the male. When the act is completed, the male attempts to guard the female from the attentions of other males, although both males and females often mate with several individuals.

Life-cycle

The adult dung-fly is mainly carnivorous, catching and eating smaller insects, but they also eat nectar. After mating females lay their eggs on the dung, where she selects small ‘hills’ on its surface, deliberately avoiding depressions and sharper pointed areas. This strategy is aimed at preventing desiccation and drowning thus giving eggs and offspring the greatest chance of survival. Depending on ambient temperature eggs hatch into larvae after 1-2 days. Larvae burrow quickly into the dung for their protection and proceed to feed on it; they also predate on other insect larvae also living in the dung. They grow rapidly and after 10-20 days the larvae burrow into the soil around and beneath the dung where they pupate.

Environmental influences 

The Yellow dung-fly has a short life cycle, a factors that has made them of interest to scientists, who have been able to study not only the insects themselves but also the effects various environmental factors has on them. For example:

The viability of a clutch of eggs depends strongly on the environment. In warmer climates a sharp drop in population occurs during the summer when temperatures increase to 28° or above. This does not happen in places with a colder climate such as Iceland, Finland and the north of Britain, nor at higher elevations.

The health of juvenile dung flies is in turn affected by the quality of the dung they inhabit, factors such as water content, nutritional quality, the presence of parasites & drugs and chemicals given to the animal that excreted it may all contribute.

 

 

 

 

 

 

 

A Windy Wildflower Walk II

27 Sunday Aug 2017

Posted by in Butterflies of Wales, calcareous grassland, coastal walks, Nature of Wales, North Wales Wildlife Trust, Rhiwledyn Nature Reserve, Wales Coast Path, Wildflowers of Wales, wildflowers on limestone, Wildlife of the Wales Coast Path

≈ 3 Comments

Tags

, , , , , , , , ,

August 3rd

Part 2 – Rhiwledyn Nature Reserve -The main track

Onwards and upwards; a flight of shallow stone steps make a steep rocky section of the path a little easier to climb (except when it’s wet & they get a bit slippery).

Pause here to admire the views back down onto the road and the many shades of green of the fields and woodland on its opposite side.

Looking down onto the road into Llandudno

Facing around to the way I’m going, the views to the right of me, seen over a rampant tangle of brambles and wild clematis on the reserve boundary, are extensive and stunning. At once pastoral and contained and wild and open to the elements.

On the other side of the track is the biggest and best patch of harebells that I have seen for years, a truly beautiful sight.

Harebell- Campanula rotundifolia

I can’t resist sitting to watch them being blown and rippled by the wind and am captivated by their charm. For me this little flower has it all. Beautiful in colour and form, they have delicacy and fragility but also great adaptability and resilience to an often hostile environment. Each flower had turned its bell back to the wind to reduce its impact; their slender but tough and wiry stems having the flexibility to bend to the wind, not break. A life lesson in a wildflower!

There were yet more of the little beauties a little higher up on the slope contrasting delightfully in colour and form with frothy lemon-yellow Lady’s bedstraw. I clambered up rather inelegantly to take a closer look. Amongst other plants, these had grown taller and in a more sheltered spot, their bells were turned to the light rather than away from the wind.

Before going back down to the track, I take another look at the glorious view across the bays to the Clwydian Hills and with sheep where they are supposed be.

click to enlarge

Back on track there is a change in ambience and habitat. There are small trees and shrubs on the boundary with the farmland sufficient to cast shade, and the sloping ground on the other side provides a windbreak. The trees are mostly hawthorn, prevalent throughout the headland as its one of the few plants not grazed by sheep or rabbits and again, tough enough to withstand exposure to fierce salty winds.

I spot a movement and see a small Grasshopper jump onto a lichen speckled rock catching dappled sunlight; the perfect place to soak up a little warmth whilst staying camouflaged.

I round a bend in the track and see – sheep! Five naughty trespassing sheep! They are strictly banned from the reserve unless invited in as their indiscriminate grazing may damage or even destroy the rarer wildflowers that grow here. Fencing prevents them wandering into the higher part of the reserve from the rest of the Little Orme where they are not restricted, so I think they got in at this field level, no doubt irresistibly tempted by the sight of the lush long grass over here. I tell them they should return to their field, but can’t see where they may have got through and they pay me no heed anyway, just amble away showing me their bottoms.

I let them get ahead, the last thing I want to do is frighten them and send them scattering and concentrate on the patch of golden flowers I see amongst the long grass on the slope. I thought at first it may be Goldenrod as I’d seen some on the roadside earlier, but soon realised it was a Hypericum – St.John’s Wort.

Another plant with several species that share the same common name, but this is the one I am most familiar with and has all the right features to be Perforate St John’s Wort – Hypericum perforatum.

St John’s Wort-Hypericum perforatum

click to enlarge

Black horehound – Ballota nigra

I apologise, but need to digress a little here to explain the significance of my next plant. Earlier on in the summer a group of NWWT members were treated to a walk around this reserve guided by its manager, Rob and a guest expert botanist, Nigel. It was a brilliant walk on many levels and we learnt a lot about our special flora and its history, about its fauna and the trials and tribulations of modern Reserve management. Typically as on any walk, even guided group ones, I lagged behind snapping interesting stuff and in a rough bramble-and- nettle patch (in the pic above), spotted the plant to the right, which is still going strong. Yet another minty-looking one I didn’t recognise. I took hasty photographs and hurried after the rest of the group. No-one else immediately recognised it either, so Nigel suggested I email the pics to him later on so he could have a better look. From them his best guess was that it was Black Horehound, reservations having been that this was a vigorous, tall specimen of a plant that usually is, in his words, ‘much scruffier-looking’ He also mentioned it smells unpleasant, so this time I had a closer look and bruised and smelt a leaf. It definitely did not smell pleasant and as all its other important bits match the botanical specs, I’m taking that as another one to add to my list of wildflowers-I-will-know-how-to-identify in the future. (Unless anyone has a different idea……?)

It’s amazing what you can see in five minutes along a short shady stretch of track. I watched a dragonfly patrol up and down at speed, pausing only in his labour several times to ‘buzz’ me and let me know I was in his space. I was hoping he’d stop so I could at least see what he was, but no, much too busy. There was yet more mint here, and one I recognised from the distinctive scent of a crushed leaf – this is Water Mint-Mentha aquatic. A similar-looking plant is Corn Mint, but it grows shorter than this and doesn’t have a ‘terminal’ flowerhead (one that crowns the top of the stalk).

Water mint-Mentha aquatica

A fresh-looking Speckled Wood rested on a sun-warmed stone on the path

Speckled Wood

and a Red Admiral flew across to seek out the nectar of bramble flowers

Red Admiral – Vanessa atalanta

There is a farm gate here which I checked for security, but tightly closed there would have been no exit for sheep. Another great Clematis-framed view from here, considerably enhanced by the clouds I think, although they were blocking out the sun at this point.

click to enlarge

At the side of the gate another member of the Lamiceae (mints & dead-nettles) family, this one I know well, the Hedge Woundwort Stachys arvensis.

Yellow Dung Fly – Scathophaga stercoraria

I moved on and round the next bend found evidence I was still on the trail of the errant sheep; a smallish neat and fairly recent deposit of fresh dung. And where there is dung there may be Dung-flies, one of my favourite insects, although I’m not exactly sure why. Perhaps because I’m keen on recycling? As I hoped, a single male Yellow Dung Fly had laid claim to the heap of treasure and was intent on guarding it. A bit of a drama then ensued, but I’m saving that for later.

To the top

I had reached the Reserve boundary, marked by a gate through which the two marked ‘Trails’ continue on to cross the rest of the Little Orme headland. There is no marked official track up to the top reaches of the reserve from here though, so getting up there is a matter of a)wanting to; b) paying attention to where you are putting your feet; c)taking care not to slip on damp grass and d) watching out for rabbit holes.

Rock-roses are still fresh and lovely up here, as is the fragrant Lady’s Bedstraw.

I followed the path chosen by the sheep; they almost always know how to find the best way upwards. They were up there now, all standing facing the view. I may have thought they were admiring it, but one of them who seemed to be in charge, maybe the mother of some of them, was bleating loudly, eliciting a response from the field below. Was she calling to her friends telling them about the feast to be had on this side and inviting them over?

Once more I reminded them they were not welcome here, but Mrs Boss Sheep just gave me ‘the look’ that clearly said “mind your own business and what are you doing up here yourself?” Once past them it became more overgrown and not as clear where to head, but I kept going in the general direction of where I wanted to be and hoped for the best. I heard a bird making some squeaky sounds and spotted him as he perched atop a gorse bush, a speckly young Robin beginning to get his adult feathers. I realised this was the first bird I’d seen and heard so far on this walk apart from gulls and the occasional cormorant flying overhead.

I also realised it was lunchtime, so time to find a sheltered spot, take a break and sit and admire the sheep’s-eye view.

 

 

 

Little Orme Level 2 and Higher

23 Friday Jun 2017

Posted by in bird's nests, Birdwatching on North Wales coast, coastal wildflowers, Little Orme, Nature of Wales, North Wales, Rhiwledyn Nature Reserve, Wildflowers of Wales, wildflowers on limestone

≈ 10 Comments

Tags

, , , , , , , , ,

Cormorants flying overhead refocussed my attention and I began the climb up the steep slope to the next level of the cliff.

I didn’t get far before stopping to watch the Whitethroat I had been heading for pre-Chough. He was singing from an old bramble stem close by and was nicely visible apart from being seemingly garotted by a twiggy branch. Song done, he flew across the track into the base of a huge bramble shortly followed in by his mate coming from the other direction, carrying food in her beak. So this is where they are nesting, no doubt tucked low down in the protective thorny thicket.

About half-way up I welcomed the excuse to pause, granted by the sight of another Swollen-thighed Beetle, this time a male sporting a splendid pair of said swollen thighs.

At the top is a reminder that the slope’s purpose was not originally as a walking track. Here stand the remains of supports and cogs for winding gear, once employed to steady trucks full of quarried stone on tracks down the steep slope, then to haul back empty ones.

TGLOVW-Winding gear remains at top of slope

This quarry face accommodates many nesting pairs of Jackdaws, whose cries often echo loudly around the bare stone cliffs. They were quiet today, the only sound made by a sheep bleating from the edge of the wall towering above. Clearly a mother, she may have been calling for her young one; I hoped he hadn’t been hauled off to market to end up as Welsh Spring Lamb in a butcher’s shop.

I took a very quick look at nesting Fulmars, didn’t want to disturb them so stayed well back.

Attractive birds with an elegant stiff-winged flight, it’s hard to believe they produce such a loud, rather harsh cry and that their tube-like nostrils are designed to allow them, inelegantly, to snort out salty water.

From up here you can look down on the flat quarried-out ‘Level 1’ of the site, with the cove of Angel Bay at its edge. The dry grassed areas are already showing signs of wear and tear.

Onwards and upwards, following the track that is both on the routes of the North Wales Coastal Path and the national Wales Coast Path. It is heavily eroded in parts, and bridged by gnarled old roots, (or branches?) of gorse.

Ravens had made me aware of their presence since arriving here today, being more mobile and noisier than usual and as I ambled along this part of the track an outburst of their calls broke out from somewhere ahead of me. I had just seen birds harrassing what I assumed to be a Buzzard and thought that may have escalated into a bit more of an incident. Getting closer I saw three birds having a bit of a to-do; two of them seemed to be attacking a third that was sitting atop a fence. Not a Buzzard.

I was still too far away to see properly, but this may have been a pair of Raven upset with an intruding one. Does it have something in its beak in the first picture, an egg maybe? I have no idea but they took off from here and continued to express their annoyance from the field below for some time.

None the wiser as to what I’d witnessed I carried on, scanning the track ahead of me, as I am wont to do at this time of year, checking for sheep poo; you never know when there may be something interesting dining out thereon. I got lucky, a fairly fresh deposit yielded a little male Yellow Dung-fly. In an awkward spot to photograph, I had no option than to kneel down in front of the dung, then almost had my nose in it to get him in close up without using the lens zoom, quietly hoping no-one came along the path to witness my odd behaviour. It was worth it; I realised he hadn’t flown off as he was otherwise occupied with a lady Dung-fly. Females are far fewer in number than males, so there was no chance he was leaving, whatever I was doing.

Yellow Dung-fly pair mating
Same image but bigger

THE CORMORANT COLONY

Reputedly the largest Cormorant breeding colony in the British Isles, this is an impressive sight, even from this distance and this is only a part of it; it continues around to the other side of the rocky outcrop in the photograph below, where there are even more of them.

I’ve shown this aspect of the Cormorant colony several times before, but this is the first time I’ve visited it at the right time to catch the birds on their nests. I was thrilled to get a glimpse of young birds in some of the nests; Cormorants usually lay 2-3 eggs, and from those I could see most seem to have hatched and grown successfully, so there must be plenty of food available locally to keep offspring and parents well fed.

Some of the young birds seemed a bit more advanced than others and were already out of the nest exercising their wings, but many birds were still sitting.

The bulk of the colony is not as easy to see, and viewing the birds involves a bit of rambling up and down the uneven cliff top, then peering down from cliff edge, but it is well worth the effort. The photograph below shows the colony to be situated well out of reach of nosy people.

Around the rock I was now upwind of the birds, so as well as amazing sights and sounds I was greeted with the equally amazing smell produced by a large number of fish-eating birds confined to a relatively small space. I wish I could share it with you!

But pungent aromas aside,the colony on this side holds another treat; right in its centre is another smaller colony – of smart little penguin-like Guillemots. Surrounded by the much bigger Cormorants I imagine it is a safe haven for them from potential predators such as gulls and the Cormorants seem perfectly accepting of them.

Cormorants and Guillemots sharing fishing space on the rocks below. There were many more birds of both species flying back and forth and hunting and diving in the water too. Cormorants stay separate but Guillemots often join together in ‘rafts’ floating on the surface of the sea.

These two birds, who I fancied were enjoying some fresher air away from the colony, is my favourite Cormorant image from the day. The birds weren’t making a sound; they gape their beaks as a means of cooling down their bodies, but it seems like they’re commenting on something out at sea. Possibly the ever-encroaching turbines of the wind farm, or maybe they were sureying for likely fishing spots. 

It was a sunny day with some cloud and really strongly windy, particularly noticeable up here at the top of the headland on its sea-facing edge, but the elements’ combined effects on the water was breathtaking. I sat for some time watching the ever-changing patterns of light and shade on the surface of the blue sea as the wind rippled across its surface and clouds cast shadows above it. It really was the colour of the photograph below and quite mesmerising.

View from the Little Orme across Llandudno Bay to the Great Orme

Birds flew past the cliff at eye level; mostly Herring Gulls, but one Greater Black-backed gull too, and a Raven gronked a greeting as he passed by; all strong birds gliding effortlessly on the wind and thermals created by the cliff face. A Rock pipit popped up over the edge briefly but popped down again when he spotted me. A Jackdaw also appeared over a ridge, but disregarded me completely and carried on foraging within touching distance, even posing for a portrait.   

THE CLIFFTOP

Returning to the main track I passed a ewe and her lambs who had found a shady and sheltered place to rest with her lambs.

I watched a 7-spot ladybird scrambling through the mossy turf. Grazed by sheep and rabbits, baked by the sun and exposed regularly to strong, salt-laden winds anything that survives here has to be tough, especially the flora. Amongst the toughest of our native flora are the thistles, the two most common species of which thrive here.

The Creeping thistle has already begun flowering and even up here was being visited by bumblebees and a wind-blown Red Admiral butterfly.

The other is the fierce-looking Spear thistle with its aptly-named long sharp spikes protecting its every part, which has flower buds almost on the point of opening now.

On the ledge beneath an overhanging rocky outcrop I was surprised to spot a clump of white-flowered plants. Getting closer I saw they were Sea campion and also Moon (Ox-eye) daisies with one of the best specimens of Salad burnet I’ve seen anywhere so far this Spring. I wonder how they got there?

Sea campion – Silene maritima

Going back down I took a photograph to remind me to say that although fading fast there is still gorse in flower and also hawthorn, but the main blossom plant now is the creamy white elder.

And another to remind myself that I can never tired of looking at this view across Penrhyn and Colwyn Bays, even when on hot days like this one much of the distance is lost in a haze.