Wood mouse opportunist

I've finally taken the bird feeders down in the garden, because there's plenty of natural food available now that spring has arrived. That means that this wood mouse, that hid amongst the flower pots near the back door and raced out to pick up the seeds that the birds scattered, will also need to look elsewhere for a free meal.

There are always wood mice in the garden, usually living in the log piles, but they do occasionally find their way indoors. We've caught five in humane traps since Christmas and released them into a hedgerow about a mile away, hoping that they won't find their way back indoors. I wrote about them in the Guardian Country Diary last week.

Dung beetle aka dumbledor aka dor beetle aka lousy watchman

 Some more pictures of the dung beetle described in today's Guardian Country Diary

' Deerness Valley, County Durham

Waiting for the clip-clop of hooves to fade away, using a polythene bag as a glove, I picked up a tennis ball-sized, steaming lump of horse manure. Checking that no one else was around – this kind of old-school natural history might seem a tad eccentric to a casual passer-by – I hurried home: I had dung beetles to feed.

 

I’d found them on the edge of a pasture and, coincidentally, had recently been reading The Sacred Beetle, Jean-Henri Fabre’s century-old account of the breeding biology of scarabs, including our native species. Could I witness what the great French naturalist first described in such fascinating detail? Fabre, meticulous observer, curious experimentalist, cautious interpreter of facts, spent years studying these ‘dealers in ordure’ whose coprophilous habits make them an agricultural asset. One study has estimated their value to the UK cattle industry, as soil improvers and recyclers of dung, at £367m per annum.

 

My captive Geotrupes stercorarius, also commonly known as dor beetles, dumbledores or lousy watchmen (they often host parasitic mites), fell out of the collecting tube onto their backs, revealing beautifully iridescent amethyst-violet undersides.

 

They have endearing parenting skills; Fabre discovered that both sexes share in tunnelling and nest preparation. They clambered over the ball of dung in the vivarium, pausing to saviour it before dropping into the grass, then digging with flattened fore-legs, forcing themselves into the soil with powerful thrusts of spiny hind limbs. Clumsy on the surface, they’re superbly equipped for subterranean life. Within a minute they had disappeared.

 

Fabre’s account describes how they dig downwards, excavate side-tunnels provisioned with what he called ‘sausages’ of ordure dragged down from the surface, then the female lays an egg in each. The next generation should emerge in autumn.

 

‘The mind, wrote Fabre, ‘is an activity, not a repository’. In some respects, naturalists live in a golden age, with so many resources available for identifying and naming what we find – AI, web sites, apps, on-line keys, social media study groups – but there’s more to natural history than compiling an inventory of biodiversity. Nothing comes close to that pleasure, first experienced in childhood, of first-hand observation, marvelling at lives of other creatures that share our planet. '

 

Here is a short YouTube video of the beetle digging its tunnel 

Goosanders

 We encountered this female goosander and her nine ducklings, not long out of the nest, when we were crossing the footbridge over the river Wear at St. John's Chapel in Weardale recently. We caught her  by surprise, tapped between a low waterfall that her ducklings couldn't navigate and us on the bridge. 

Outside of the breeding season she would have taken flight in an instant, but she had no option but to stick with her flightless ducklings, swimming in agitated circles, with her ducklings clambering on her back. We moved on quickly, leaving her and her family to white-water raft down river and away to safety. 

This was a single-parent family: drake goosanders undertake a moult-migration to Norway while the duck is still incubating her eggs; he won't be back until late autumn.

I wrote about this encounter in the Guardian Country Diary this week.

Golden-ringed dragonfly

Dragonflies are the subject of my Guardian Country Diary today.

This is the peak period locally to watch these spectacular gold-ringed dragonflies Cordulegaster boltonii, which have the longest body (but not the greatest wing span) of any UK species. We discovered this female in the early morning, torpid after a cool night, resting on a patch of rushes next to a footpath.
.

There are several prime locations for this impressive insect here in the North Pennines. One of the best is in Hamsterley forest, near Spurleswood beck, which has the kind of crystal clear, highly oxygenated water and stony stream bed that forms a perfect breeding habitat. Another is along the river Derwent near Blanchland in Northumberland. A third is in Weardale, in a shallow stony beck that runs down the hill into the top of Tunstall reservoir near Wolsingham in Weardale.

While I was photographing this individual she began to warm up her flight muscles, first with just the merest hint of a vibration in her wings, until she was like a helicopter on the verge of take-off. Then she let go with those legs, which are of little use for walking but are used for gripping perches and catching prey in mid-air ..... and she was gone, hunting flies over the bracken.

The marvels of dragonfly vision are almost beyond our comprehension. We have trichromatic vision, with sensors that detect red, green and blue, which together define our visual spectrum. Dragonflies have sensors that detect at least five wavelengths, in addition to ultra-violet which is beyond our perception, and some species have thirty sensors that each detect a different wavelength, so their colour spectrum is vastly more complex and subtle than ours.

It's an interesting thought that those bright colours that we admire when we watch a dragonfly are not the colours that they see.

Then there are those massive compound eyes, each composed of thousands of separate facets (ommatidia), which give them highly sensitive flicker vision. When fast-moving objects cross their field of view they are tracked by a succession of ommatidia that convey the information to the brain.

Their amazing eyes, coupled with their speed of flight and extreme manoeuvrability, make them deadly aerial interceptors.

Soundtrack to Summer

Today's Guardian Country Diary is about grasshoppers.

These lovely insects, that provide a soperific soundtrack to late summer, are sun-loving so their greatest species diversity in the UK is concentrated in southern England.

We have two common species here in the North Pennines ......

... the green grasshopper  Omocestus viridulus....

.... and the meadow grasshopper Chorthippus parallelus.

Both 'sing' by stridulating - dragging those pegs on their hind femur over the hard edges of the wing. The meadow grasshopper has the most varied song and both sexes chirrup, though the female's song is quieter than the male's because those stridulatory pegs tend to be smaller in females.

Males have three distinct songs - a loud one for attraction, a quieter one for courtship and a stucatto one during mating. 

They can be hard to spot because they are well camouflaged amongst dry grasses and heather, and on warm afternoons their -leap-flutter-glide escape technique can make them hard to catch.

Grasshoppers hatch from overwintering eggs as a tiny worm-like organism that then undergoes four moults as the nymph grows. This is a meadow grasshopper in the  penultimate instar before becoming an adult - it still has wing stubs but these will reach full size during the next moult. 

This female, sitting in the sun amongst bell heather, has lost her hind leg on the left-hand side. Nymphs in early instars can regenerate lost legs but this one must have lost the limb after becoming an adult, perhaps to escape the grip of a bird's beak.

Surprisingly, there are documented instances of grasshoppers that have lost a hind leg being able to stridulate and respond to a mate's song with the remaining limb. The impediment must make for lop-sided leaps though!

Butterfly alcoholics

Thursday's Guardian Country Diary is all about intoxicated butterflies.

We had our best ever plum crop this year - too many to eat, store in various forms or give away all of them. Branches broke under their weight.

The beneficiaries from those that fell on the ground were red admiral butterflies. I piled some plums on the bird tables, where the natural yeast on their skins fermented the juice to produce an alcoholic liquor that stupified the butterflies that fed on it. The whole area under the tree smelled of vinegary alcohol after a few days in the sun.

Sometimes there were a dozen or more red amirals on the bird table, where they usually tolerated each other as long as their wings or antennae didn't touch. If they did they flicked there wings, clearly irritated.

If  other butterfly species tried to join them - and peacocks and speckled woods sometimes did - the red admirals became more aggressive and chased them away.

The red admirals were clearing drunk and had lost their inhibitions. If I put the fermented plum pulp on my fingers they extended their proboscis and drank from my skin.

And if I deliberately chased them off they just flew around my head, landing in my hair or on my clothes and hands.

Some days they were so drunk that I could poke them on the nose and they wouldn't take flight.

The last of the plums has now rotted and the red admirals have returned to their favourite nectar source in the garden - Buddleia x weyeriana, which flowers right up until the frost. But all the time the plums were available they completely ignored it, confirming my suspicion that they had fallen under the influence of the demon alcohol.

Quarry life in early autumn

Today's Guardian Country Diary is about autumn gentians and heather bees in a Weardale quarry.

Weardale is a valley full of old mines and quarries, mostly legacies of the lead industry and quarrying of the Great Limestone. Most of these are now worked-out or abandoned, like this one near Hill End at Frosterley.

From a distance it looks a bleak place, but when you take a close look there are some fascinating plants and animals here.

The bottom of the quarry is flooded, with a shallow lake and islands in the centre, surrounded on the north side with weathered rock spoil tips ...

..... and the vertical rock walls are being colonised with plants and even rowan trees.

In autumn the thin turf that covers the weathered spoil tips is covered with a tapestry of small flowers, like this eyebright and ground ivy .....

.... and this wonderfully fragrant wild thyme. Everything that's more than about one inch high is grazed off by rabbits, except for ....

... a fabulous display of autumn gentians Gentianella amarella.

Rabbits must find these distasteful because in late August there are thousands of them in flower, unmolested. 

The short calcareous turf, well-drained and with most of its nutrients leached away by rain, seems to suit this delightful little plant.

The quarry's other autumn speciality is its colony of heather bees Colletes succincta. These little bees are slightly smaller than a honey bee and each digs its own nest tunnel in the terraces of earth that build up where sheep make regular tracks across the spoil heaps. The bees excavate individual tunnels, where they lay their eggs and provision them with heather pollen, but they nest colonially. 

This colony has several hundred individuals, whose nest tunnels are sometimes just a few inches apart. 

Smart-looking little bees, with their ginger furry thoraxes and striped abdomens.

These bees are only around for about 3-4 weeks in late summer, when the heather comes into bloom. Their first priority is to mate and the males patrol just a few inches above the ground, intercepting the females when they come within reach. Sometimes several fall to the ground, locked together in a ball of wings and legs.

After mating the bees shuttle backwards and forwards to the heather moorland, in this case several hundred metres distant, to collect food to feed their brood when they hatch from the eggs, then cap the tunnels. Autumn rain washes away their little spoil heaps of excavated soil and all trace of them disappears.

Just a few weeks in the sun, then the rest of their life cycle is spent underground.

A Day in the Life of a Dung Fly

Thursday's Guardian Country Diary is about dung flies Scathophaga stercoraria

These common insects carry out their courtship on dung but are particularly fond of cow-pats. This is a male, awaiting the arrival of females. They prefer fresh dung, before it becomes too crusty, for attracting the females that scent the trysting place from downwind.

Males usually outnumber them so there is intense competition for a mate, which females usually choosing the largest suitors. Their sex lives have been intensively studied because these insects are easy to rear under laboratory conditions - you can read about the intimate details of their mating habits by clicking here.

Their Latin generic name Scathophaga (originally Scatophaga, but it seems to have acquired an additional h) means 'dung-eater' but it is only the larvae, which hatch from eggs laid in animal dung, that do this. The adult flies are formidable hunters, needing to catch and eat other insects to complete their sexual development before they are capable of breeding. This one has caught a small hoverfly and is holding it between its front legs, in much the same way that mantids hold their prey.

Many dung flies suffer a gruesome fate when they are infected with a fungus called Entomophthora. Its hyphae grow into their host through its spiracles and invade its body, digesting it until it weakens. In the final phase the fungus turns its host into a zombie, affecting its nervous system in a way that makes it climb towards the light. The flies die clasping grass stems, where the spores erupt through their body and are passed on to other inquisitive flies that investigate the corpse.

The pictures below, taken using a microscope, show the sticky spores on the dead dung fly host.