A Sting in the Tale

by Dave Goulson

  Very slowly, over the last decade, the meadows have begun to fill with flowers. It has been frustratingly slow. Even if conditions are suitable, the flowers have to come from somewhere, and this limits how fast they return. Some, such as poppies, can survive for years as seed in the soil, but most of the perennial plants that typically thrive in a flower-rich meadow cannot, so seeds have to arrive from elsewhere. Some flowers have seeds which readily disperse over a huge distance. Dandelions are a well-known example – their seeds hang below a fluffy pappus of fine hairs and can drift for miles on the wind. They have lots of relatives – mouse-ears, cat’s-ears, hawkbits and so on (the last taking its name from an ancient belief that hawks ate them to improve their eyesight). All share the same seed-dispersal mechanism, and so these were among the first flowers to arrive. The meadow is now a sheet of yellow in June and July, but only from late morning through to the afternoon, for these flowers close overnight and they are not early risers. Wild carrot followed close behind; the seeds are light and flattened, and so can blow a short distance on the wind. They seem to be thriving in the drier soils in the higher parts of the meadow. Other plants are much slower. Cowslip seeds are heavy and round, so they will always fall close to their parent. There were some cowslips along the side of the track to the farm, and these have been slowly spreading into the meadow, but they have only made it a few yards so far.

  From a bumblebee’s perspective, legumes are among the most vital components of a wild-flower meadow. Plants of this family include clovers, trefoils and vetches, as well as garden vegetables such as peas and beans, and they have an unusual trick that allows them to thrive in low-fertility soils. Their roots have nodules, small lumps inside which live Rhizobium, bacteria that can trap nitrogen from the air and turn it into a form usable by plants. Most plants are severely limited in their growth by a shortage of nitrates, which they require to construct proteins, and yet nitrogen, the element from which nitrates are made, comprises 80 per cent of the air that surrounds them. By enlisting the help of bacteria, legumes get around this problem – they feed their pet bacteria on sugars, which they obtain by photosynthesising, and in return the bacteria provide them with nitrates. This relationship gave legumes a huge advantage in the days before artificial fertilisers were widely deployed. Ancient hay meadows are full of clovers, trefoils, vetches, meddicks and melilots, able to outcompete grasses because they alone have access to plentiful nutrients. Most of these plants are pollinated by bumblebees.

  Over the last fifteen years or so I have gathered a lot of records as to which bumblebees feed on which flowers, separated into visits for pollen and visits for nectar. One of the striking features of these data is that some bumblebee species, such as the brown-banded carder, the garden bumblebee and the ruderal bumblebee, seem to get nearly all of their pollen from legumes. What is so special about legume pollen? To find out, I gathered pollen samples from various different flowers – a remarkably tricky business, which bees make look ridiculously easy – and sent them off to a lab in Cambridge where their nutritional composition was analysed. It turned out that legume pollen is especially rich in protein. What is more, the protein in legume pollen was itself unusually rich in ‘essential amino acids’, those which animals cannot synthesise for themselves. To ensure the fidelity of bumblebees, it seems that legumes offer pollen which is unusually rich in high-quality protein. Since pollen is the only source of protein available to bees, it makes perfect sense for them to selectively visit the flowers that provide the richest source.

  There is an interesting parallel to be made here with vegans and vegetarians. Bees are the vegetarian descendants of wasps, having turned to feeding on pollen and nectar instead of the flesh of animals. They visit legumes to obtain protein. In much the same way, human vegetarians and especially vegans tend to include a large proportion of pulses in their diet because they provide a rich source of protein and particularly of essential amino acids – and pulses are the seeds of legumes. Legumes can afford to put plentiful protein into both their pollen and their seeds because of their root nodules.

  The mutualistic relationships between bees, the flowers that they pollinate, and the bacteria that live within the roots of those plants are at the heart of the functioning of a natural, species-rich meadow. The problem is that these relationships can be ruined by application of a sack of fertiliser, which allows the grasses to swamp the legumes and other wild flowers, swiftly resulting in a bright green, flowerless sward, with no legumes, no Rhizobium, and no bees. In the farming world this is known as ‘improved’ grassland. In the 1940s, Britain had in the region of 15 million acres of flower-rich grasslands. It is hard to get precise figures, but about 250,000 acres remain; a staggering loss of over 98 per cent. Fertilisers were cheap, and successive governments were keen to persuade farmers to boost productivity, so ecosystems that had taken hundreds of years to develop were subject to swift and wholesale destruction. Most of what remains of our flower-rich grasslands is in tiny patches of less than 5 acres, usually on nature reserves. I cannot find equivalent figures for France, but I suspect that they would be equally depressing for lowland areas such as the Charente as I have yet to discover a single sizeable patch of flower-rich grassland anywhere near Chez Nauche other than my own. It is hardly surprising, then, that many bumblebees and other insects have disappeared from much of the countryside, both in Britain and across Western Europe, for most of the flowers, including their favourite foods, have all but disappeared.

  Unfortunately most legumes, like cowslips, have heavy seeds and no clever mechanism for dispersing them on the wind, and so they are slow to return once they have been lost. Many, such as vetches, have chunky pea-like seeds, so unless they are carried by ants – which they sometimes are – they do not disperse more than a foot or two each year. To speed them up a bit, I have cheated a little in my meadow by collecting red clover and bird’s-foot trefoil seed from nearby verges and sprinkling it by hand. Whether this has helped is hard to say, but both species are now scattered in patches through the sward, and each year the patches spread further. Clumps of bush vetch have appeared, as have other legumes such as hare’s-foot clover. Slowly, the false oat grass has declined, presumably because the nutrients it needs are disappearing.

  Aside from creating my own bumblebee reserve, I had another motivation for wanting to buy some land. Much ecological research requires long-term experiments, but long-term experiments are very hard to maintain. Grants for research generally run for only three years, and cash-strapped universities rarely have sufficient land that they can set aside over many years for such purposes. I had my fingers burned in this respect at the University of Southampton. I set up an experiment to study hybridisation between red and white campions in a walled garden owned by the university.29 It involved planting out dozens of patches of plants, either red, or white, or mixtures of the two, and then studying them over time to see whether red or white or hybrid offspring came to predominate. These are fairly long-lived plants so I planned to run the experiment for at least ten years – only to have the experimental plots sold off to developers after just eight, before the most interesting results could be obtained. If I owned the land myself, such disasters could be avoided.

  Recent research by Richard Pywell and colleagues at the Centre for Ecology and Hydrology in Oxfordshire suggests that the restoration of species-rich meadows can be accelerated by use of yellow rattle, a hemiparasitic plant. Yellow rattle is a relative of foxgloves, but is a plant typical of ancient hay meadows. Much-loved as a nectar source by long-tongued bumblebee species, it is a pretty but unpretentious annual that grows to about a foot or so tall, with small yellow flowers. Its name derives from the seeds, which rattle within the dried pods. Yellow rattle is unusual in that it parasitises other plants, particularly grasses, tapping into their root systems and extracting nutrients.30 Since the grasses are being parasitised, they grow less, leaving more room for other flowering plants. Pywell demonstrated that sowing rattle seed into
an English meadow significantly boosted the diversity of flowers present by suppressing growth of grasses.

  This seemed like an interesting idea to follow up in France, since adding rattle might both directly provide flowers for bees and boost the colonisation process. It occurred to me that there were many other hemiparasitic relatives of rattle that might be deployed instead of or as well as rattle, and that it would be worth trying out as many as possible to evaluate which were most effective. To this end, in September 2010 I arrived at Chez Nauche with a posse of helpers, volunteers from among my PhD students and the staff of the Bumblebee Conservation Trust. We marked out 120 plots, each 10 by 10 metres square, using aluminium plates pegged to the ground. Before sowing the seeds we had to prepare the ground, which first involved cutting and removing as much vegetation as possible. I have an ancient ride-on mower which I used at first, but after half a dozen plots it spluttered to a halt, and for the life of me I couldn’t persuade it to go again. I rushed out and bought a push mower, the largest I could afford but ridiculously small for the task in hand, and I spent the week mowing. Behind me, the rest of the team followed, raking, sprinkling seeds, and stamping them in with their feet. We used mixtures of seeds including two species of yellow rattle, two of cow-wheat, eyebright, and red bartsia, all of them hemiparasites, and we included control plots in which nothing was sown.

  A farm track runs along the north boundary of the field, and on the second day I noticed Monsieur Fonteneau driving slowly past with one of his large sons. Both of them were staring at us intently, presumably wondering why this eccentric Englishman was mowing neat squares into the huge field with a small garden lawnmower, while a gang of helpers raked, sprinkled and performed strange shuffling dances. Over the following days other local farmers came to watch in bemusement. None of them came over to ask what we were doing, which was a relief as my French would not have been up to the task. I feel sure that our behaviour was the subject of considerable speculation in the nearby village bars.

  My long-term aim is to follow these plots for many years, assessing the diversity of flowers in each. In spring 2011, eight months after we had set the experiment up, I returned to see whether the seed had taken. I could hardly bear to look as I drove down the track to the farm, but of course I did. At first glance there wasn’t much to see. Over the next week, and with help from my PhD student, Leanne Casey, and Andreia Penado, a visiting Portuguese scholar, we identified and recorded the amount of every plant species in every plot, eagerly looking for the hemiparasitic species. We did the recording blind, in the sense that we deliberately did not check which mix had been sown in which plot before we evaluated them – otherwise we might have subconsciously biased our efforts, for example by looking harder for particular flowers in the plots in which they had been sown. One of the advantages of having a rather poor memory is that there was no chance that I would have remembered which were which from the previous year.

  I was thrilled to find rattle in some of the plots, although there wasn’t very much, but try as we might, we could not find any of the other hemiparasites. When I subsequently checked, the rattle had at least appeared in the plots in which it had been sown. No other differences were evident between the plots, but of course we wouldn’t have expected them so early. It will take a year or two for the hemiparasites to become established in number, if they survive at all. I returned in 2012 and the pattern was much the same. In another four years or so I will be able to say which of the hemiparasitic species is best – at the moment, my money would be on rattle, which would be a slightly boring result since it will not add much to what Pywell and colleagues have already demonstrated. Nonetheless it will be valuable to show that the other hemiparasites don’t work, if this is the case, so that other folk don’t bother to try the same thing.

  It has been incredibly rewarding to watch the large but rather dull grassy field that I bought a decade ago slowly turn into a flower-rich sward. Every year I discover that a few more flower species have somehow arrived. I keep a running total, which is now in excess of 130 plant species if I include the shrubs and trees in the field margin, and I am sure that there are more to find.

  With the arrival of plentiful flowers, a myriad of insects have returned. Most insects can fly, and so it does not take them long to find good habitat when it is present. The field is now alive with butterflies every summer, including many which I would have regarded as spectacular prizes in my butterfly collecting days. Swallowtails soar powerfully over the field, searching for fennel on which to lay their eggs. Scarce swallowtails, with more angular wings and a slightly scorched appearance that gives them their French name le flambé, swoop around my peach trees. Their larvae eat the leaves, which doesn’t do the trees any good, but I can’t begrudge such beautiful creatures. Glanville fritillaries lay batches of eggs on the plantains in the meadow. Their jet black larvae are gregarious, spinning dense webs in which they live together through the winter. On one memorable occasion a male purple emperor soared past, his iridescent wings flashing in the sunlight.31 So far I have recorded over 60 species of butterfly, almost as many as live in the whole of the British Isles.

  Among the more spectacular insects, praying mantis lurk on the tall stems of the wild carrots, attempting to snatch passing flies. Male great green bush crickets sing incessantly and deafeningly through the warm days of summer, in an attempt to impress a mate. On the ground, chubby black field crickets sit outside their burrows, their more melodic chirrups drowned out by the bush crickets. They have enormous oversized heads, which make them resemble cartoon characters. On a warm summer’s evening, male stag beetles fly clumsily past, their wings barely able to carry the weight of their heavily armoured bodies. They seem to suffer an appalling mortality rate, for the local kestrels snatch them from the air and settle on the hay bales in the field to dismember them. In some years every bale has two or three stag beetle heads on it – the heads seem to be too tough to eat, so are discarded. Distressingly, the heads remain alive for a day or two, their antennae twitching and their great jaws slowly opening and closing.

  Kestrels are not the only predators to take advantage of the bonanza of prey. Voles and mice have proliferated and attract hen harriers, which hunt low over the meadow. The local barn owl population appears to have boomed judging from the rate at which their pellets are deposited in my attic and the surrounding barns, although I rarely spot more than one or two of them. Impressively long western whip snakes bask on the stone walls of a collapsed barn to warm themselves in the morning, before stalking through the long grass for small mammals. They are a lovely dark olive with bright green speckles, almost iridescent in the sunlight. They live up to their name and can move like lightning so, as my boys and I have discovered, they are a great challenge to catch.

  Even these fierce predators appear to have an enemy, a top predator that stalks the farm at night. I have found the remains of kestrels, snatched from their roost under the eaves of the house, and on one occasion I found the wing of a barn owl beneath one of their favourite perches – the rest of the bird having presumably been consumed. Most gruesomely, one early morning my boys discovered the remains of a particularly large and splendid whip snake which we had seen several times in the preceding days. All that was left of the 5-foot snake was a 6-inch portion from the middle – the remaining 4.5 feet having been eaten. I’m still not certain what this mysterious beast is. It can clearly climb, is nocturnal, and is big enough to eat a large amount of snake in one sitting. I have found scats that may belong to it, in appearance similar to those produced by pine martens with which I am familiar in Scotland. I’ve installed Velux windows above the bedrooms upstairs, and one morning awoke to find sizeable footprints across the glass – the beast had paced right above my head in the night. The prints were not crystal clear, but they roughly fitted with those of a large marten of some sort. Beech martens are said to be found in this part of France, so this is my best guess as to what it is, and I would dearly love to see it.
Perhaps one day I will borrow one of Steph’s bumblebee nest cameras and try to film its nocturnal activities.

  Of course with all the flowers in the meadow, the bumblebees have also returned en masse. Shrill carders are now an everyday sight, hardly worth interrupting one’s ablutions for. Red-shanked carders are also two-a-centime, distinguished from the even more common red-tailed bumblebees by the red hairy bristles on their legs. The long-tongued ruderal bumblebees remain scarce but regularly put in an appearance, feeding mainly on the red clover. All of these species are exceedingly rare in Britain, so it is a joy to see them thriving here. I have planted a row of lavender along the front of the house under the windows, so I do not even need to leave my picnic bench by the front door to see a plethora of butterflies, hummingbird hawkmoths and bumblebees. In July of 2009 I was enjoying a morning coffee when I spotted a slightly unusual-looking bee on the lavender. I think my heart knew what it was before my head had really had time to take in the details. It was, unmistakably, a short-haired bumblebee, the species we were working so hard to bring back from New Zealand to the UK. There are very few places in Europe where these bees are regularly seen, and to my knowledge western France was not supposed to be one of them but nonetheless here it was. Imagine my excitement, and the frenzied rush to grab my camera so that I could record the moment. I must confess that I have not seen one since then, but I hope that one day they might become regular residents.