Bee Quest

by Dave Goulson

  The reintroduction continues to the present, and like that of the reintroduction of the short-haired bumblebee to Kent – a project with which I have been personally involved – the eventual outcome remains uncertain. They have recently switched to Spain for the source population for the release, following genetic studies that showed the Spanish population was most similar to that which had once lived in the UK. There is also a suspicion that the Russian birds have a strong instinct to migrate south in winter, causing some birds to leave the site and then find themselves in unsuitable areas where they stand little chance of survival. A mix of Spanish and Russian birds now exists on the Plain – I wonder how a Spanish female might react to the exotic sound of a Russian male’s flatulent sneeze, and vice versa. Unfortunately, to my knowledge no home-grown chicks have yet survived a winter – hopefully it will happen eventually. A recent Tweet described seeing a drove (the collective noun for bustards) of five males flying past Stonehenge – what a magnificent sight that must have been. Perhaps one day a viable population will establish itself, though I suspect it will always be small and teetering on the edge of extinction, unless bustards can somehow master the skill of vertical take-off and landing.

  My favourite non-bee denizens of the Plain are rather smaller than the bustards, and have a peculiar mutualistic relationship with the tanks. I had been told to look out for these creatures, and so on my visits to the Plain that first summer I peered excitedly into every muddy puddle I came across. As you might imagine, the tanks churn up the tracks across the Plain whenever it rains, taking huge gouges out of the earth which then fill up with rainwater. By late spring these tend to be drying up, pea-soup green and stagnant, and this is the perfect time to see fairy shrimps. It was on just my second visit to the Plain that I saw my first one – a semi-transparent, greenish-brown creature perhaps three or four centimetres long, lying on its back, and using its innumerable bristly legs to rhythmically waft its way along just beneath the surface of the water. The eyes were black and protruding on stalks from each side of the head, and the tail long and forked – altogether a most bizarre creature. I got a little too close and it darted down into the murky depths where I could not see it, but after a few minutes it rowed itself back into sight. They turned out to be quite common on the Plain, though I never tired of looking for them. Sadly, this is one of the only places in Britain where they can reliably be found – the filling in of temporary ponds and the pollution of those that remain mean that the number of surviving populations of this species has dwindled to about half a dozen in the south-west of Britain. But the tank activity on the Plain provides them with plentiful habitat, and also a means of transport. Fairy shrimps are highly specialised creatures that can survive only in temporary ponds – they are virtually defenceless against predators such as fish or dragonfly larvae, so they can only survive in ponds that exist for such short periods that predators do not have time to arrive. Their eggs hatch in the winter rains as the puddles fill, and the shrimps grow fast in spring, using their many legs to sieve the water for the algae, bacteria and so on which are their food. Before their pond dries out in summer they must complete their development and produce eggs, which survive being dried out and then sit in the summer dust of the Plain waiting for the water to return. The eggs can survive for many years if the conditions aren’t right for hatching. In the past the eggs, mixed up in the sticky mud of a drying summer puddle, may have been spread from place to place on the legs or bodies of large mammals such as aurochs or boar – the latter’s constant truffling about in the earth may also have helped create small ponds for them to live in. More recently, I’d imagine that horses and carts passing along unpaved roads would have created a network of suitable habitat all over Britain, which the advent of tarmac did away with. These days, on Salisbury Plain at least, the mud-spattered tanks and other military vehicles are thought to do the job pretty effectively, spreading eggs along the tracks so that a high proportion of the suitable puddles are occupied. This serendipitous synergy between army vehicles and a tiny, delicate shrimp epitomises the relationship between the army and wildlife on the Plain. The army purchasing strategy in 1897 didn’t set out to create a huge nature reserve – one imagines that this would have been somewhere near the last thing on their minds – but that is nonetheless what happened. Although the purpose of their estate remains primarily that of providing a training ground for the troops, these days the army is sensitive to the needs of wildlife, and it has adapted to a new role as custodian of the rare plants and animals that flourish on the Plain. Some of the army personnel are wildlife enthusiasts, spending their spare time mapping and recording the populations of butterflies and flowers, in between dashing about in tanks and practising shooting one another.

  To return to the bees, you may be wondering what exactly I found out from my extended jolly on the Plain. You’ll recall that my aim was to find out more about the requirements of our rare bumblebees, particularly with regard to their preferred flowers, so that we might better look after them. I did end up with a very large spreadsheet, with the many different flowers listed down the side, the bee species along the top, and an awful lot of numbers in the middle, indicating how many of each bee had visited each flower type. Of course, most of the records I amassed were for common bumblebees – red-tails, in particular, which are inordinately abundant on the Plain. The large majority of all the bees I recorded were visiting quite a small number of plants: viper’s bugloss, red clover, sainfoin, melilot, knapweeds, red bartsia and thyme. Frustratingly, data for the rare species were sparse – even on the Plain, the largest tract of flower-rich grassland in Western Europe, the rare bumblebees were still scarce. For the shrill carder, my entire data set included one male on black horehound, one worker on red bartsia, and one worker flying round my head – not a very comprehensive picture of the foraging behaviour of the species, and certainly no basis for recommending the mass planting of bartsia and horehound all over the UK, though I can think of worse things to do. Likewise, I had just two sightings of ruderal bumblebees, three of red-shanked carders and four of moss carders – a depressingly small haul from a whole summer of work.

  However, I did have slightly more respectable data sets for some other rare species, enough to suggest that brown-banded carders seem to be legume specialists, visiting mainly red clover, sainfoin, melilot and bird’s-foot trefoil, and that the broken-banded bumblebees were mostly on sainfoin, red bartsia and field scabious.

  On my last day on the Plain I reviewed what I had found over the summer, going through my messily scribbled notebook while tucking into a lovely dish of locally caught potted pike (man cannot live on pie alone). All in all, it had been an interesting start, and it had been wonderful to at least get to see these rarities on the wing, but it was also clear that I needed to go further afield if I really wanted to find out more about these elusive beasts. I needed to find somewhere where they were still as common as in Sladen’s day, which was clearly not going to be easy.

  CHAPTER TWO

  Benbecula and the Great Yellow Bumblebee

  On earth there is no heaven, but there are pieces of it.

  Jules Renard

  As our tiny, noisy, twin-prop eighteen-seater plane banked hard right to come in for the runway at Benbecula airport, I looked directly down on a scene straight out of a Caribbean holiday brochure: a crescent of dazzling white sand lapped by a crystal-clear turquoise sea. Above the beach the dunes were splashed with colour: drifts of yellow, purple and red flowers. No palm trees to be sure, but in every other respect one might have been arriving on a subtropical isle, ready for a week of relaxation, sunshine, piña coladas and reggae music. I was sharply returned to reality when, a few minutes later, I stepped out of the plane into the icy wind; this was most definitely not Antigua.

  Benbecula airport is tiny, but it does at least have a runway. If you fly to the nearby island of Barra, your plane lands on the beach itself, and flights can only come in when the tide is out. This is t
he most remote corner of the British Isles, the Outer Hebrides, a chain of low-lying islands sixty kilometres to the west of the Scottish mainland in the North Atlantic. It was August 2005, and I was here on a mission: to see the great yellow bumble-bee, properly known as Bombus distinguendus, a contender with the shrill carder for the title of Britain’s rarest surviving bumblebee.

  One hundred years ago, great yellows were found all over the UK. They were never particularly abundant in the south, but there are records from almost every county from Cornwall to Sutherland, and Norfolk to Pembrokeshire. They were always more common in the north, seemingly preferring cool, wet parts of the country, though not the uplands. Sadly, the great yellow did not much enjoy the twentieth century. Populations in the south started to disappear from about 1940 onwards. Even the flowery ranges of Salisbury Plain were not enough to support them, and within forty years the species had disappeared from the entirety of England and Wales and from most of mainland Scotland. By the end of the millennium they were only to be found on a few Hebridean Islands, Orkney and in a scattering of tiny populations along the far north coast of Caithness and Sutherland. Now, the strongest surviving populations are in the Uists, the central part of the Outer Hebridean chain, comprising North and South Uist with Benbecula sandwiched between the two. Which was, of course, why I had chosen to come here: to see the last of the great yellows, to learn more about this scarcest of British bumblebees, and perhaps to do something to help save them from extinction.

  I was met at the airport by my PhD student Ben Darvill, who had spent the previous two summers in the Hebrides studying the bumblebees to be found there and taking DNA samples for genetic work. He was trying to find out whether these isolated island populations were suffering from inbreeding, and the gradual loss of genetic diversity that can occur when a population is small and cut off from gene flow – isolated from others of its kind. Ben was in his decrepit VW camper van, a vehicle so ancient and damp that moss and occasionally small fungi sprouted from the insides of the windowsills. It was to be our accommodation for the next week.

  I had expected it to be something of a struggle to find great yellow bumblebees. Seeing most scarce, highly endangered species requires considerable dedication – it had taken me nearly two months to see my first shrill carder on Salisbury Plain – but in the Uists great yellow bumblebees were everywhere that year. It was somehow almost disappointing. I saw my first one thirty yards from the airport, on the large pink flowers of a hedge of bushy roses growing along the edge of a garden. She was a worker, scampering around amongst the mass of stamens, emitting high-pitched buzzes to shake free the pollen. Tremendously excited, I spent a long time photographing her from every conceivable angle, anxious that she might be the only one I saw on my trip. However, I had to admit that she didn’t really live up to the name – she wasn’t particularly big, and nor was she especially yellow. The ‘average-sized, straw-coloured bumblebee’ would be a more appropriate name, if less catchy. She was rather pretty, nonetheless: tawny-blond all over apart from a clear black band across the middle of the thorax, the great yellow is one of our easiest bumblebees to identify.

  We headed south from Benbecula, away from the ugly gaggle of concrete buildings near the airport, and I was struck once again by the extraordinary beauty of the area. To our right we passed a succession of perfect, white-sand beaches, with not a single soul on any one of them. The sun sparkled off the sea beyond. To our left, in the distance, gentle hills rose, cloaked in purple heather. The road itself passed through a habitat known as machair, the secret of the survival of great yellow bumblebees in the Hebrides. Machair is one of the rarest habitats in the world – in fact, nearly all of it that exists anywhere is in the west of Scotland and the west of Ireland. It is formed from a flat plain of wind-blown shell sand – tiny grains of broken shells that have been ground up by the action of the oceans over millennia. The machair plain is sheltered from the prevailing westerlies by the dunes above the beach, but catches fine grains of sand that settle in their lee. The shell sand is inherently alkaline, and very poor at retaining nutrients, which wash through and leach away in the frequent rain. Further inland still, the bedrock rises into low, ancient hills that are clothed in a thin layer of acidic peat, which supports mosses and heathers, the more familiar moorland vegetation found across much of Scotland. So the machair is a flat ribbon of land, never more than a kilometre or two wide, running down the west coast of these islands, sandwiched between the dunes and the sea on the west and the hills on the east.

  A flat plain of nutrient-poor sand may not sound terribly promising, but this plain supports a wealth of wildflowers, and hence a diverse and thriving bee community, along with much other wildlife. Counter-intuitively, wildflowers proliferate where nutrients are scarce. In particular, legumes dominate – their root nodules, packed with nitrogen-fixing rhizobium bacteria, enable them to take nitrogen from the air and turn it into useable nitrates, vital for building proteins. Most other plants such as grasses cannot do this, and so they grow slowly on the machair, leaving lots of space and light for the legumes to flourish. As a result, as we drove along, the landscape on both sides was a carpet of red clover, white clover, tufted vetch, kidney vetch, and bird’s-foot trefoil – all plants that are also abundant on Salisbury Plain, and all of them well loved by bumblebees, with different bee species tending to have slightly different favourites. If bumblebees go to heaven, it might well look something like this.

  We pulled over and strolled through the knee-high flowers, butterfly nets and cameras at the ready. Ben had endured weeks of rain before I arrived, sheltering in his mouldy van: there isn’t a lot to do in Benbecula in the rain. I was incredibly lucky, for the weather while I was there was atypically fine; the sun did its best to blaze down from a cloudless sky, though it never got terribly warm, for at this latitude the sun never gets too high in the sky. A short-eared owl glided by, hunting for voles. It was odd to see an owl hunting in the daytime, but that is normal for this species. Perhaps at this latitude the summer nights are so short that they have had to become active in the day. As we walked, our feet disturbed hundreds of bumblebees, busy extracting pollen and nectar, making hay while the sun shone. I was particularly excited to see moss carder bees in abundance. In mainland Britain they are very hard to find, and they are also exceedingly tricky to distinguish in the field from the common carder and the brown-banded carder, as I had discovered on the Plain. In the Outer Hebrides, there is no need to worry about subtle distinctions, for the other carder species do not live out here, and in any case Outer Hebridean moss carders look quite different to their mainland counterparts. We have no idea why they should be different, but here they have a rich chestnut-coloured thorax and black underbelly, which combined with their ‘teddy-bear good looks’ makes them very handsome bees indeed. We also have no explanation as to why, on the most outer Hebridean islands, moss carder bees are by far the most common bees, bucking the trend found elsewhere across Europe. Here, they seem to be the dominant species, the superior competitor, while elsewhere in the UK they are invariably rare and seem to be hanging on by the skin of their mandibles.

  Moss carders are not the only bumblebee to have a unique colour form only found in the Hebrides. We also saw heath bumblebees, the queens of which are normally rather small with three yellow stripes and a white tail. Here, the queens were gigantic, with reddish brown tails. I was initially quite confused as they superficially looked like the big buff-tailed queens one commonly sees in most of Britain, but I knew that buff-tails don’t occur in the Hebrides.

  We spent the whole afternoon in that sea of flowers – I spent much of my time on my belly, camera at the ready, stalking great yellows and moss carders, and trying not to squash too many flowers. They were mostly workers, but there were still a few queens about, even in august, for the season up here starts very late, with most queens remaining in hibernation until June. The queen great yellows were still not really big enough to justify their name, but
were nonetheless extremely splendid insects. More by luck than judgement, some of the photos that I took on that day came out unusually well, and they have been used many times since in promotional literature by the Bumblebee Conservation Trust and on the cover of my scientific tome on bumblebees. Every time I see them, I am reminded of lying belly down amongst the flowers, the Hebridean sun on my back and bees buzzing all around.

  We spent the next few days touring to the bottom of South Uist and back up to the top of North Uist, recording what we saw, identifying the flowers that the different bees were feeding on to add to my growing database, taking genetic samples,fn1 and snapping as many photographs as we could. I was struck by how similar the flora was to that of Salisbury Plain – most of the common flowers were the same, despite the big difference in climate and geology. In fact, I should not have been surprised – both habitats are nutrient poor and well drained, and both are growing on the calcareous shells of long-dead sea creatures. Were it not for the distant roar of the surf, and the consistently chilly air temperature, one could easily have been on Salisbury Plain or one of the unspoiled fragments of flower-rich grassland on the South Downs. In addition to the many legumes, there was lots of knapweed, the tall purple flowers favoured by male bumblebees, perhaps because their large flowers on sturdy stems make perfect platforms on which groups of males can lounge about drinking nectar before going in search of a mate. There was also plentiful yellow rattle, a ‘hemi-parasite’ that parasitises grasses and sucks nutrients from their roots.fn2 There were also lots of arable weeds such as corn marigold, poppies and corncockle. Arable weeds have had a tough time in recent decades, for these are annual species that used to thrive in the disturbance created by annual ploughing and cropping. In days gone by, cereal fields were routinely washed with the blue of cornflowers, or red with swathes of poppies. Grains collected for sowing the next year were often contaminated with wildflower seed, so they were accidentally spread from place to place by man. These weeds would also thrive when fields were left fallow for a year, flowering in profusion and scattering seeds that could then sit in the soil for several years waiting for a chance to germinate. Poppy seeds are particularly good at this, being able to sit, inactive, in the soil for decades until the right moment arrives. Modern seed-cleaning methods now remove unwanted wildflower seeds, and most cereal crops are sprayed with herbicides that kill all broad-leaved plants, so most arable weeds have declined enormously. Some, such as downy hemp nettle and thorowax, are now extinct in the UK, while many others are declining and some teeter on the edge: corncockle, shepherd’s-needle, Venus’s looking-glass, pheasant’s eye, and so on. Surely they are worth saving for the evocative names alone?