Bee Quest Page 7

  The only plants able to grow upwards and flower were spear thistles, protected by their fierce spines, and in places the thistles were taking over, forming dense stands that were extremely uncomfortable to push through. In fact, the thistles turned out to be a life-saver for us, for it was on their flowers that we did find a few bumblebees, though there were ‘only’ moss carders, mostly males. How they managed to survive through the year on such sparse resources was beyond me. Perhaps this was the tail-end of a dying population. We took our bee foot samples, and when Ben analysed them back in the lab it turned out that many of the males were diploids. Sex in bees is determined in a rather bizarre way, quite different to our own. In bees, males normally develop from unfertilised eggs, and so have half the normal amount of DNA, with just one copy of each chromosome; they are ‘haploid’, in scientific jargon. Females develop from fertilised eggs, and so have the full complement of DNA with two copies of every chromosome; they are ‘diploid’. This all works very reliably in a large, healthy population with lots of genetic diversity, but it malfunctions in inbred populations. The reason for this is that sex is actually determined by a single gene, which occurs in the population as dozens or even hundreds of different forms, known as alleles. Any individual that has just one allele becomes male, and if it has two different copies it becomes female. Haploid individuals, with just one copy of each chromosome, must by default have only one allele of this gene, so they must be male. Usually diploids have two different alleles, since the chances of them getting two identical copies from their two different parents are slim; hence diploids are normally female. The problem arises when the population is small, for in small populations genetic diversity is lost; the number of different copies of any particular gene is steadily eroded, a process known as genetic drift. If the gene that determines sex loses its genetic diversity, so that there are only a few different alleles left in the population, then it becomes common for a queen bee to mate with a male who has the same allele as herself. When she lays fertilised eggs, intended to be daughter workers, half of them inherit identical copies of the gene and instead become diploid males. Since these don’t do any work in the colony (in bumblebees, males never do any work to speak of, unless you count copulation), she is losing half her workforce, and her nest is likely to expire. The presence of so many diploid males on the Monachs was not a good sign for this remnant population of moss carders.

  Yet despite the sheep and the depressing lack of all but a few inbred bees, I had an idyllic day. The tide was low at lunchtime and I made my way out across the sandbars to the second and then the third and endmost island. I ate my packed lunch, a rather low-quality but nonetheless enjoyable pepper steak pie, sitting on the dunes looking west towards Nova Scotia. On my way back I was vomited on by a young fulmar, not an experience I would choose to repeat but worth doing once just for the novelty. I’d been making my way along the north shore, between the dunes on my right and a rocky tidal ledge to my left, and had not noticed the large burrow amongst the tussocky marram grass until it was too late. I’d not heard a sound for hours apart from the lapping of the waves, the call of a few gulls overhead and the baaing of the sheep, so I nearly jumped out of my skin when there was a loud, guttural, retching bark close by and an instant later my leg was splattered with a hefty dollop of half-digested fish. The stench was horrendous. Apparently, surprising walkers in this way is a favourite pastime of fulmar chicks. The parents create nests in rabbit burrows close to the shore, sensibly preferring to nest on offshore islands where there are few predators. Once the chicks are old enough they are left alone during the day; fluffy, off-white little monsters, they sit in the entrance to their burrow waiting for passers-by, whom they target with surprisingly accurate jets of projectile vomit. Of course it is presumably meant to ward away predators; I was not inclined to go too near to a burrow again, and after being forced to smell their vomit I would certainly not fancy trying to eat one, so I guess it works pretty well. It took me ages to wash my shorts clean in the shallows, and despite my efforts the smell stuck with me for days (my apologies to the lady who had to sit next to me on the plane home). There were dozens more fulmar nests along that section of coast, and I had to pick my way between them very carefully.

  A little while later as I climbed through the dunes, having left the fulmars behind, I became aware of a distant clamour; incongruously, it sounded like a primary-school playground in the lunch hour, a hubbub of noise that slowly swelled as I approached the top of a tall dune system. After the fulmar experience I was a little cautious, wondering what other noxious creatures might be lurking in wait for me, and so I started to creep slowly through the dunes, hunched down in what I recall from my experiences in our school’s ludicrously incompetent cadet force as being called the ‘monkey run’ position. As the noise got closer I moved into the ‘leopard crawl’, edging forward on my tummy to peer over the crest. Below me on the beach were perhaps 1,000 Atlantic grey seals, hauled up on the warm sand. There were lots of pups, old enough to be gambolling in the shallows, nipping each other in play, barking, yelping, and annoying their parents. It was a magnificent sight – I can think of very few occasions when I have seen such numbers of truly wild large animals anywhere in Britain. Better still, they were entirely unaware of my presence, and I spent ages photographing them with my camera, though the range was a little too distant. I lost track of the time, and eventually had to sprint back across the wet sand, splashing through the shallow water as the tide came in, to get back to the island where our boat was pulled up.

  It had been a fascinating day, but it held one more surprise for us during our return journey. Despite the wind and spray I was nodding off in the boat when it suddenly veered to one side, almost causing me to fall out. As I grabbed the rope along the rubber wall of the boat, a huge grey-brown fin passed within touching distance, protruding perhaps a metre from the sea, followed by a second, much smaller one. The dorsal and tail fins of a basking shark: Craig had swerved to miss it. Sadly the boat frightened it, and though we circled back to get a better look it had sunk beneath the choppy waves. Harmless filter feeders, basking sharks are the second biggest fish in the sea, growing up to ten metres or more. Sadly, these slow-moving giants have been hunted to extinction in many parts of the world, but here in the Hebrides there are still reasonable numbers.

  The future of this remote corner of the UK, and of the wildlife it supports such as the great yellow bumblebee, is far from secure. Our studies of the genetics of small, isolated populations of bumblebees have found that these populations have little genetic diversity, exactly as we would expect. This means they have limited capacity to evolve if their environment changes, and they are likely to be susceptible to outbreaks of disease. It is very likely that this same issue of inbreeding affects many of the other organisms that live here, for most inevitably survive as small, isolated populations. Once upon a time, when these species were also found on the mainland in abundance, extinction of island populations could be reversed by re-colonisation, and genetic diversity could be boosted by occasional immigration. Now, for many Hebridean species, there is little chance of that. They are on their own.

  Worryingly, this unique environment faces many other challenges. I have already mentioned the changes to crofting that are taking place, and the depopulation of these islands. One might think that fewer people would be good for wildlife, but much of the floral diversity of the machair is the result of human activity – the small-scale, low-intensity farming. The move towards large-scale sheep ranching is not favourable for bees or flowers – as we saw on the Monachs, too many sheep can be a disaster. At the opposite end of the spectrum, land abandonment can be almost as bad.

  In the longer term, there is a potentially more devastating threat, in the form of climate change. The great yellow is a species well adapted to cold climates. It is big, with a long, shaggy coat, both attributes that help it to keep warm in the cool, damp climate of north-west Britain. It was always most common i
n the north, and as it declined in Britain in the face of loss of flower-rich habitats, its range contracted northwards to the places to which it is best adapted. It cannot go any further north. A warmer climate is likely to favour the displacement of the great yellow by more southerly species moving northwards. Since there is nowhere for the great yellow to be displaced to, that could be the final nail in the coffin for this species in the UK. Climate change also poses another threat. The machair is just inches above sea level, and thus even small rises in sea level – as predicted in the coming decades – might mean that the machair becomes inundated by the sea. This is particularly likely if extreme climatic events such as storms become more common – as they are predicted to do, and as we have already seen in recent years – because these can rip holes in the protective coastal dunes, allowing the sea to burst through. Of course, if this were to happen, then more or less all of the species that live here would be lost, not just the bumblebees, and there is very little that anyone could do locally to combat this.

  Perhaps the best long-term hope for the great yellow in Britain is to work on boosting its populations on the Scottish mainland. There is a string of small populations clinging to the northern coast of Caithness and Sutherland, and here at least they are not going to be inundated by the sea as the coast is mostly rocky and steep. The Bumblebee Conservation Trust has done a lot of work in the area, encouraging farmers and working with local communities to sow flower mixes and rotate grazing to allow pastures to flower. The Royal Society for the Protection of Birds are also busy, trying to create and manage habitat for both corncrakes and great yellows at Durness, Dunnet Head, and elsewhere. Corncrake numbers are tiny but increasing. The extent of the range of great yellows on the north coast seems to have increased slightly, though it is unclear whether this is due to an increase in recording efforts or to a genuine spread of the bee.fn5 Let’s hope it is the latter. Realistically, there is little chance that either species will ever reclaim their former range, and most of us will rarely if ever get to see or hear them, living as they do in such remote places.

  It is often argued that the best way to justify conservation efforts is to calculate the value of the services that wildlife provides – in the jargon of the day, we calculate the ‘ecosystem service’ that they provide. Bees are often used as an example; pollination is worth perhaps $215 billion globally, calculated as the value of crops we would lose without bees and other pollinators. It thus makes sense to look after them, because they look after us. The same argument can be rolled out for many other organisms; ladybirds and hoverflies that eat greenfly, flies that decompose dung, and so on. It is an argument that does not sit well with me. Why should nature only have worth if it does something for us? Just how self-obsessed are we? In any case, this approach falls flat on its face when presented with the corncrake or great yellow bumblebee. Recent studies suggest that most crop pollination is delivered by just 2 per cent of the bee species in an area – the common ones, as you might guess. Economically, great yellow bumblebees are utterly inconsequential; they probably contribute a tiny bit to the pollination of a few garden vegetables on crofts in the Uists. In truth neither corncrakes nor great yellow bumblebees – nor a great many other plants or animals – contribute anything meaningful to ecosystem services – we would not be noticeably worse off in any easily measurable way if they were one day to shuffle off – but I for one would consider that a very sad day indeed. We should not ask what nature does for us, but instead ask what we can do for it. I don’t know when I will next get a chance to go to the Hebrides to see these fascinating creatures, but the world is a richer place for their being there.

  CHAPTER THREE

  Gorce Mountains and the Yellow Armpit Bee

  Look deep into nature, and then you will understand everything better.

  Albert Einstein

  My travels in search of rare bumblebees have taken me to many corners of the UK over the years – from the Scottish Highlands in search of montane species to the iris-lined ditches of the Somerset Levels via the coastal dunes of Pembrokeshire, the Fens of East Anglia and the rocky cliffs of Cornwall. In almost all of these places – the sole exception being the Outer Hebrides – the nationally rare bees remain very hard to find, even in the most spectacularly beautiful of habitats with more flowers than one could shake a stick at. Yet the old books on bumblebees suggest that these species were once quite common, if never as abundant as the ubiquitous species such as the buff-tailed bumblebee. In Frederick Sladen’s The Humble-Bee from 1912, he talks about shrill carders and short-haired bumblebees (the latter now extinct in Britain) as if they were very familiar creatures to him. The short-haired bumblebee he describes as ‘common in many localities in the south and east’ and the shrill carder as ‘common in a good many places’. The ruderal bumblebee was in his day known as the ‘large garden bumblebee’, suggesting that it was regularly found in gardens. He found and dug up the nests of all of these species and describes them in detail – whereas in over twenty years of studying bumblebees I have never found a single nest of any of these species, even with the help of a succession of sniffer dogs that we had trained by the army specifically to find bumblebee nests.fn1

  It seemed to me that the changes that have occurred to the landscape in Britain are so profound that, even in the relatively unspoiled fragments of habitat, perhaps all that remains is a pale shadow of their former natural glory. It is hard to know for sure. Without a time machine, we can never really know what it would have been like to be a naturalist rambling through the British countryside in the eighteenth or nineteenth centuries, other than by reading their books and notes. We might infer from the fact that there are old recipes for cowslip wine – which require as the first step the collecting of two buckets full of cowslip flowers – that they were once much more common than they are now, but we can’t know how common, or how abundant the bees were that visited them, or how numerous the worms that burrowed beneath their roots. This said, it occurred to me that there might be a way of gaining an insight into what Britain used to be like – by going to Eastern Europe. I had heard that in parts of Eastern Europe agricultural systems remained little changed, having escaped the drive for increased yield that afflicted Britain from the Second World War onwards, and which was subsequently driven throughout Western Europe by the Common Agricultural Policy’s labyrinthine and often perverse system of subsidies for farm ‘improvement’.

  Poland seemed like a good place to start. Perhaps there I might find species such as the shrill carder in abundance, sufficient that we could gather lots of data on their habits, favoured foods, preferred nesting places, and so on. Old museum records suggested that the rugged mountains on the borders of Poland, Slovakia and the Czech Republic were extraordinarily rich in bumblebees, with many species that had never occurred in Britain. The prospect of potentially seeing exotic species such as Bombus veteranus and Bombus wurflenii was mouth-watering.fn2 Friends returning from holiday reported seeing farmers still using horses to pull their carts, and old-fashioned handmade haystacks in the fields. It sounded as if farming here might still be much as it was in Britain one hundred years ago, the nearest thing to a time machine that I was ever likely to find. And so it was that in August 2006 I found myself on a cheapo-jet flight to Krakow with Ben Darvill and Gillian Lye, the latter having just started a PhD with me on the nesting biology of bumblebees. We didn’t tarry in Krakow, despite its famed beauty and charm, for we were here to see bees – we hired a car and headed due south from the airport, towards Zakopane in the foothills of the Tatra Mountains.

  The Tatras form the western end and the highest part of the 1,200-kilometre-long Carpathian mountain range, which extends from Poland south-east through Slovakia, Ukraine and Romania. On the Polish side they are a popular skiing destination in winter and favoured by hikers in the summer, though attracting mainly Polish holidaymakers rather than those from further afield. The Tatras are quite recently formed by geological standards – along with
the Alps, they were thrown up when Africa, rushing headlong in a northwards direction at the approximate speed of a growing fingernail, crashed into Europe, a slow-motion collision that began about 100 million years ago and is still happening today. Being young, the Tatra Mountains have not had long to erode, and so they are steep-sided with jagged peaks – very reminiscent of the Alps, but a little smaller, with the highest peak being at 2,650 metres. We found a small hotel in Zakopane and that evening we dined heartily on sausages and pierogi (dumplings),fn3 on the pretext that we would need plenty of energy for hiking up the mountains in search of bees the following day.

  The morning got off to a bad start. We drove out of Zakopane on the only road that appeared to head into the mountains, failing to notice a tiny sign that said ‘no entry’ in Polish. At the end of the road was a policeman, whose job it was to fine the succession of unobservant tourists who drove up. Our wallets duly lightened, we drove back to Zakopane and caught the tourist bus, which took us back past the policeman – who still seemed to be doing good business – to the bottom of the mountains. On the Polish side the Tatras are a national park, and we had to pay a hefty entrance fee to enter, but at least when we began to ascend the steep mountain trail we were not unnecessarily burdened with cash.

  The path initially wound through dense forests, a mix of dark conifers and deciduous trees, with very few flowers or insects of any sort in evidence. After a couple of hours of steep ascent we emerged into an alpine meadow, and suddenly there were flowers and bees everywhere. Dramatic indigo spikes of monkshood rose amongst the yellows of St John’s wort and saxifrage, mauve powderpuffs of scabious, and the delicate blue bells of campanulas. On the more disturbed, steeper slopes where rock falls had recently occurred, swathes of rosebay willowherb clothed the mountainside in pink. We scrambled about – trying to catch bees on such steep meadows was challenging as one couldn’t keep an eye on the bees while watching one’s footing, so all three of us fell over a few times in our excitement. Ben and I were old hands at catching and identifying bumblebees in the UK, whereas Gillian was pretty new to the whole thing, but pretty soon all three of us were confused. Compared to the UK, we seemed to be encountering a bewildering array of species: some looked familiar, others were similar but slightly odd, and others still were quite unlike any UK species. We’d known to expect this and had tried to prepare, but nonetheless it was clear that it was going to take some time to get to grips with all of these new bees. We took lots of photographs, and some voucher specimens so that we could confirm our identifications.fn4