Was it the full moon?
Or the sudden warming in temperatures last week? Or impending Easter – which won’t fall this late in April again until 2030? Or the threat of predators? At that stage unseen.We’ll never know, but after a full beehive inspection last week, when every frame was lifted out and examined – and still the queen bee wasn’t spotted among the increasing numbers of workers covering most of the frames, the bees became stroppy. For the first time since this hive has been on site. They obviously felt that my mentor’s comment, rating their behaviour as just 3 out 10 on a scale of potential aggression during the inspection, needed some adjustment.
Our subsequent tea on the terrace was aborted after we got buzzed in warning fashion by a bee.
The following day, it was warmer still, and Fiona and I both got “head” buzzed in a similar way – not the direct in your face smack that I’d experienced years earlier, but still unnerving. Later in the afternoon the alert level ratcheted up a notch, when our weekly garden helper got stung beside the eye. After appropriate short term first aid William left early to recuperate, whilst we pondered the way ahead, with 5 insect averse grandchildren due to arrive about 4 hours later, and our planned first ever “pop up” garden open day just 2 days later.
After much discussion, garden visitors were emailed and warned about the situation and we decided that with the grandchildren, we’d better get them down to the stream whenever we could, and hold the annual garden Easter egg hunt after supper, when the temperatures were falling. Interestingly, nearly all of our garden visitors still wanted to come.
In glorious weather, and with water levels very low, the stream side proved to be a great success and very popular with adults and children alike. There’s nothing like pottering in sunshine in a stream, collecting sticks and building mini dams and dens.
In fact, we’d started these a few months back, when our son had created one over the Christmas holidays – a simple low, angled affair which had already survived a couple of spate events, and was really designed to divert the main flow back to where it had been before storm Callum rearranged stream banks, and large chunks of our wet meadow disappeared overnight.
Such incomplete low structures add habitat diversity to the stream, by creating longer pools with a range of gravel sizes, to complement the rills and riffles. With the low water levels there was much to observe – Pond skaters, Gerris lacustris, venturing onto the larger pool’s surface. Click here for more.
Fiona commented on the shadows they create.
There must be some interesting physics to explain the large dark circular shadow pads, brightly rimmed, which must be formed from the very slight depressions created in the water surface film, by their thin hydrophobic, waxy hair covered legs – the key to their walking-on water capability. Look in the image below, how the water surface surrounding the leg/water contact area, lacks any clarity.The middle legs are the real powerhouse for pond skaters, the rear pair more of a rudder mechanism for steering, and the front pair used to detect vibrations in the surface film, which might indicate a struggling insect, and then aid holding onto it – for pond skaters are predators, with quite fearsome sucking mouth parts, or beaks. Notice too, how having only recently emerged, that the observed “pond skater” is in fact a mating pair. The smaller male atop the larger female.
Beneath the surface, the year’s crop of small finger smudged salmon, sea trout or brown trout parr are already growing fast and carving out their small feeding territories within the pools. Holding station, waiting for any food that heads their way. Food supply is the main limiting factor for the population density of these parr, which will have hatched out from eggs which somehow survived the winter spates buried deep in the gravel spawning redds. Last year’s 3 or 4 inch fish all seem to have disappeared from the stream by spring, which makes me think that the parr are indeed migratory fish, washed further downstream and eventually out to sea.
It seems the warm weather is a trigger for several caddis larvae, of the order Trichoptera, to decide it’s time to leave their watery stem and gravel encrusted homes and metamorphose for aerial life. Clinging onto rush stems on the water’s surface, I watch many prepare to escape. Leave their aquatic confines for a brief aerial fling.
They’ve gone by the afternoon. I dug out my original and slightly worn “Observer’s Book of Pond Life”, by John Clegg, which I remember helped to set me off on my interest in the natural world decades ago. The design and materials used in the larval cases is specific for the different species of caddis fly. The one above looks like belonging to a Brown sedge, Anabolia nervosa.
As we lifted the stones, both Fiona and I thought we glimpsed the odd dark eel like fish which rapidly wriggled off. Perhaps we had eels in the stream?
Then I found a bullhead, Cottus gobio. A wonderful four inch long catfish-like bottom dweller. And even a clutch of eggs beneath another stone. It reminded me of the Hypostomus plecostomus catfish I used to keep as an algal cleaner in my tropical aquarium as a teenager. Interestingly sold as I recall, as just a “Plecostomus”. Though not actually even in the same phylogenetic family as Cottus, just the same class of Actinopterygii, or ray based finned fish, which constitute nearly 90% of all fish anyway.
The bullhead has some great adaptations for its life in an upland stream – very strong pectoral fins, a flattened body with eyes more on the top of the head, no swim bladder to help it hug the bottom, and an unusual eye structure with a double cornea which includes a gap in between the layers, which possibly helps it in an environment which will often be full of fast moving debris.
The male excavates a nest beneath a stone, and will attract a mate by creating loud knocking sounds. The female lays eggs in batches within this created space, which are fertilised by the male. Apparently, bullhead sperm is more similar in structure and function to that of animals which use internal, (i.e. within the body) fertilisation, so perhaps locating a spawning site out of the worst of the current is critical to allow the bullhead sperm a decent chance to successfully fertilise the eggs? Spot another gravel clad caddis larva moving over a stone bottom right in the image above – maybe this one is the species Sericostoma personatum, the adult of which is called Welshman’s Button sedge, click here for an image of the adult fly.
Unusually in British fish, the male bullhead will defend the nest against predators, including the ever present caddis fly larvae. The male bullhead fans the eggs with his pectoral fins to keep water circulating over them – in the absence of this, they’re very prone to fungal infections. The eggs hatch in 20 to 30 days and the young will then disperse. The limiting factor for population growth seems to be food supply, and these fish are very sensitive to water pollution. However, given how quickly I found examples of these fish, it could well be that our stream supports numbers around 1 per square metre, which has been reported elsewhere. Click here for more detail on their life cycle and ecology, in a great pdf from Natural England.
As we returned to the stream after lunch out on Good Friday, our eldest granddaughter called out, from ahead of us, that there were 3 eels in the stream. Doubtful, I reached the bank side and indeed she was right. Barely 4 feet from where we stood were three intertwining eel-like fish, about 6 inches long and the thickness of a finger, sinuously twisting and focusing their activity on a very small area of the gravelly stream bed. As we all made it to the viewing point, it became clear that this was a prelude to spawning, and Fiona spotted that the fish were using flexing body movements and physically picking up stones in their mouths to fashion some sort of shallow depression. However, my limited knowledge of eel ecology included the fact that all eels migrate to spawn in the Sargasso sea, that unique area of the Atlantic that has no immediate land borders, defined by four different rotating ocean currents. Someway East off the coast of North America. So maybe these weren’t eels at all? Click here for more on the Sargasso sea.
Then they must be lampreys! How exciting since none of us had ever seen one before, and here in front of us they were performing their mating and spawning ritual, completely unfazed by our presence, noise, and even stick waving by the youngest of our clan.
After several minutes watching we moved downstream and I kept looking for any more. I spotted one dark form swimming purposefully upstream. An hour or so later at the spawning site, there were indeed four fish in the mating group.
Returning on my own, just before dusk, the number had risen to 8, I think, though it’s difficult to count a writhing mass of lampreys. Good Friday was the night of a full moon.And being clear, warm and dry, I was intrigued to see the state of affairs the following morning, so around sunrise at 6.10 a.m. I walked back down to the stream. They’d all gone. It was only when looking at the second You Tube clip below, that I realised that the accumulated plant debris in the spawning site, just downstream of the larger stones, wasn’t “just plant debris”, but a collection of caddis larvae which had moved into the site for breakfast eggs!
It’s taken me several days to find out more about the ecology and life cycle of the lampreys we saw – the smallest of the British lamprey species, the Brook lamprey, Lampetra planeri, ( from the Latin, lambere = to lick; and the Greek, petra = stone, Planer being the name of a German naturalist). Indeed, I’m including several links later on, because no single source seems to have the complete range of information in them. This is in part because no one has yet managed to rear them in captivity – it’s been possible to collect eggs from such spawning sites, or indeed from mature adults and strip spawn them, but after the eggs have hatched, their remarkable life cycle involves the juvenile larval forms, known as ammocoetes, settling in parts of the stream bed with muddy or silty deposits. They bury themselves with just their mouths at the surface, and then spend the next 5 years or so feeding on plant and animal debris like small invertebrates, algae and even pollen which washes past.
They never migrate to sea, and never attach with their suckered mouths to parasitise larger fish, unlike their British cousins the larger river and sea lampreys. I didn’t realise this when I recorded the voiced over You Tube clip, so please excuse this error!
What’s more, after these several years of largely secretive and hidden development, they metamorphose. Though there’s no great detail I could find on this, it’s only the adult form which develops the typical round suckered mouth which you can see being used to shift pebbles in some of the images here. At the same time, their alimentary tract atrophies, so the adult lamprey which emerges from this metamorphosis in late summer or autumn, never actually feeds at all over the winter and into spring. It simply hides and moves around the stream, largely by night, waiting for the spring triggers of warming water – over about 11 degrees C, and some think the pull of a full moon, to migrate further upstream for spawning.
During the brief mating episodes, the female will often anchor herself with the suckered mouth to a pebble in the mating redd, whilst the male anchors himself to the back of her head, using his sucker. Then he wraps around her body bringing their joint anogenital openings into close proximity, and there is a short period of vigorous vibration during which time eggs are released, fertilised, and some will end up being buried under gravel during this process.
Other eggs will wash downstream. In any event, surviving viable eggs will hatch into larvae after just 3 to 4 days. Once mating has been completed, the adults die within a few days – or indeed are taken by predators. Fortunately we haven’t seen a heron here for several days, since the lampreys would have made easy pickings.
Finally, I should add that lampreys, and their closely related cousins the marine hagfish, which have similar round mouths with rasping teeth, are some of the oldest species of vertebrates on the planet. They diverged from the mainstream of vertebrate evolution perhaps 500 million years ago, and have several distinctive features:
- They are the only surviving forms of jawless fish. So, whilst all other vertebrates which developed later on have hinged jaws for chewing, lampreys and hagfish simply have their round suckered mouths. They are thus known as cyclostomes or agnathans, to separate them from all other vertebrates with hinged jaws – the gnathostomes.
- They have primitive gill slits on each side of the head, (7 in lampreys, 12 in the case of hagfish), and a simple eye and nostril.
- They lack bilateral appendages like fins or limbs. All other vertebrates have these – or at least did before they became vestigial or “lost” as in eels or snakes. Other fish and tetrapods have matching paired fins, legs or arms.
- They don’t have a conventional vertebral column with articulating mineralised or cartilaginous vertebrae. Instead they have much simpler cartilage-like nodules, which give their adult body structure. In part this contributes to their extremely flexible body.
- Lampreys have both a primitive innate and also an adaptive immune system, though this is entirely different to that found in other vertebrates.
- Unlike most other fish, lampreys lack any scales.
- Lamprey larvae, their ammocoetes, are effectively blind for all the years that they live, feeding buried in silt or mud. Their eyes at this stage are much like those of a hagfish, being small and buried beneath the skin with a very poorly differentiated retina. Only at metamorphosis into the final adult stage, after all those years of blindness, does the eye develop to end up quite similar to that of other vertebrates, erupting at the body surface, developing extra-ocular muscles, though no intra-ocular ones, a conventional type eye lens, and a fully functioning retina. Meanwhile the cornea splits into both sclera and dermal layers, which means that the eye can move relative to the rest of the skin, as it does in other fish. Hagfish eyes remain extremely primitive structures throughout their lives. Click here for more on the significance of these differences from an evolutionary point of view.
- They don’t have conventional vertebrate brain development, though do possess the precursor of a distinct neural crest. Click here for more on the special evolutionary status of lampreys. And in a late discovered link to some of the distinctive features of hagfish and lampreys, there are even recipes for hagfish slime with gruyere cheese scones (hagfish produce copious amounts of this from special slime glands along the side of their bodies!) and lamprey Bordelaise! I kid you not, but this piece was from the Wisconsin School of Veterinary Medicine, which perhaps explains their sense of humour, (and in 2021 the link no longer exists!) Lampreys were however a significant delicacy food dish in the UK, a tradition which continues to this day, when the city of Gloucester prepares a unique lamprey pie for the monarch on special occasions. This tradition stems from a huge fine being imposed by King John on the city, centuries ago, when it failed to deliver his annual Christmas lamprey pie. The custom was dropped in Victorian times, but revived in the 1950’s. So Queen Elizabeth has received several impressive examples. Click here for images of how ornate these pies can be, though the last one had to use imported Canadian Lampreys, since the ones remaining in the river Severn are now so few in number that they are protected by law. In a final historical link, some readers may recall that Henry 1st was reported to have died in 1135 from a “surfeit of lampreys”. For much more detail on a fascinating piece of English history, click here for an excellent piece of research ad writing by Elizabeth Chadwick on the wonderful History Girls Blog site.
The brave souls who visited the garden for our pop up opening the following day, Easter Saturday, had to endure my enthusiastic description of this special spawning event, and were able to have a first look at some of the video clips of this. The garden looked lovely, the weather was sunny and warm, and we had a great afternoon, without the large numbers of visitors which had overwhelmed us in February.
Fortunately, the bees behaved up to a point – late afternoon, around tea time, one or two bees decided to do some slightly aggressive head circling and buzzing, but visitors sensibly withdrew inside and the day ended with an after-supper Easter egg hunt for the grandchildren skillfully laid by Fiona, once the temperatures had dropped a little.
Thinking that was the end of the excitement for the weekend, we were proved wrong, as on Sunday morning, our oldest grandchild remarked on the very big wasp inside our high ceiling living room, next to a Velux window. Fiona quickly spotted it wasn’t a wasp, but a queen hornet, so once more our guests decamped to the stream whilst I figured out how we could tackle this large insect. Hornets will certainly catch and eat honeybees, though we’ve never seen one at Gelli before, and perhaps this had contributed to the bees’ grumpiness.
Eventually, with patience, my bee suit, a butterfly net, and an old can of Vapona, we removed the potentially troublesome insect. It certainly has a fearsome set of jaws, but it was a relief to see, up close, that it was a European hornet, Vespa crabro, and not an Asian one, which are currently viewed as a huge potential threat to British bees, should it ever become established in the UK. There is a very good Natural History Museum ID guide to Asian hornets which I found, after this event. Click here. Recently updated, it hints that Asian hornets may already have become established in a couple of parts of the UK, so vigilance is called for. A quick guide to their differences is that the Asian hornets have an orange face, yellow legs, and a blacker body than the native European one. Although European hornets will take honeybees on the wing, Asian hornets lie in wait by the beehive and grab worker bees as they return to the hive, chopping them up, and feeding the thorax to their own larvae. Since there can be up to 1,000 hornets in their colony, the significance of this threat becomes clear.
For now, with cooler weather, the hornet removed and the moon having waned, the bees are once more, calm (see later!), though we’re still avoiding those areas closest to the beehive until the cool of the evening.
Only a few benign “nomads” remain, yet another species witnessed for the first time during the last week, but difficult to photograph and identify. These are species of small bees, which look a little more like wasps, which survive and complete their life cycles by finding the larval nests of other solitary ground nesting mining bees. The female nomad bee enters these tunnels, and lays eggs which devour the host larva, and later emerge as nomad bee offspring.
There’s never been a better spring that I can remember for Orange-tip butterflies, Anthocaris cardamines. We’ve seen Holly blues, Celastrina argiolus, Peacocks, Aglais io, Red admirals, Vanessa atalanta, and even a fleeting glimpse of another Brimstone, Gonepteryx rhamni, in the recent warm sunshine. But so many Orange-tips. I even managed to capture, just, 3 males in the same frame, nectaring off sparse bluebells in the North West corner of our wet meadow – a reminder of Steven Falk’s tip to look in this part of any field early in the morning, as the warmest spot for any feeding insects.
The images were meant to be added to this post this early evening, but after having to deal with a swarm of bees this afternoon, and some very speedy frame and hive construction and manipulations, it’s meant a late evening to get it finished, after a 5.30 a.m burst of creativity this morning.
Never a dull moment here at present.
I’ve walked the banks this generation past,
Watched these mill waters tumble, glide,
Now clear as gin, then swiftly,
Impenetrable, silt laden, brown.
Seen the spraints and caught the patient heron’s
Yet missed you all.
But this Good Friday’s lunarcy filled me
With awesome wonder. Caught shamelessly in flagrante,
Your glorious all afternoon long orgy,
Entwining, sensuously, in this the gentle brook,
Warmed, beneath this gentle breeze.
I saw them first. Three twisting eels, just feet from where I stood.
The bank here firm, not giving way.
Near where the morning’s simple slanting dam
Was piled with random stones,
This day. He died and bled, to take away my sin.
Grumpy, excited as I’ve never seen before,
I wonder if I’ll remember, when I’m as old and grey,
Two generations hence, this morning?
Before the eggs were laid amongst the flowers,
These suckered fish. Will I believe?
In Life and Death and Resurrection?
Or contemplate just what those hands have made?
Or even evolution?
We’ve seen the stars. We’ve heard the thunder.
But now this special day’s the time. Predestined,
Pulled by some invisible lunarcy. We simply know.
After all those blind, long years, encased in
Cold deep mud, mouths gaping. Waiting for whatever
Can sustain and grow our feeble larval form.
Lying, not living.
But now our eyes are wide and opened. Our wasted guts,
No longer filled with hunger pangs,
For this is life.
This glorious special day.
We’re well rehearsed, innately ready,
Fine tuned by half an aeon’s worth of
Dead end, jawless, round mouthed practice.
The slits and suckers, simple clues to those
Who dare to watch our lithesome tea time passion.
And glimpse us roll those well worn stones.
As though our very lives depended on it…
And then, too soon, it’s over. Spent. The bodies, gone.
Drifting lifeless, seawards, our offspring will inherit
This glorious earth. Or water.
And we’ll proclaim:
How Great Thou Art!