LITMIR.BIZ

Скачать книгу

the others about the location of the food. But how? Von Frisch and his colleagues discovered that the information was being conveyed through a pattern of repeated body movements which he called ‘dancing’.

      It was taking a while to get out of the sheep-market car park. I had to negotiate my way through a slow reversing dance of Range Rovers and sheep trailers, as they manoeuvred to offload their noisy contents into the sheep pens. A bee floated indecisively across my windscreen, plainly not on a von Frisch mission.

      How had he worked it out? The researchers’ method was to put a small dish of sugar water some distance from the hive. The dish might not be discovered for several days, but as soon as one bee found it, and returned to the hive, others soon emerged and made their way to exactly the place where the dish was. It seemed to be precision navigating.

      The first time I read about this research, I remember thinking: how on earth could you keep track of a single bee within a hive? But there was a simple solution. The researchers marked the pioneer forager with a coloured dot while it was feeding, so that they could track its movements when it returned. The hive had glass walls so that they could see what was happening inside. And there they saw the dance – a ‘round’ dance, with the bee turning in circles alternately to the left and the right.

      The behaviour has now been observed by hundreds of researchers. It’s been filmed, and – these days – computer-analysed. The dance is evidently saying, ‘Hey, everyone, come and see what I’ve found, not far away!’ If the nectar source is especially rich, the dance language is especially lively. ‘Hey, you really have to see this!’

      I finally got out of the sheep-market, and followed the little back road around to the junction with the A5 at the edge of Gaerwen, near where the Lit – tle Chef used to be. It’s a quiet road now. The new dual-carriageway A55 across Anglesey took most of the traffic away, and the café went with it. But there are enough points of interest along the A5 to keep the tourists coming. Llanfairpwll is just a couple of miles away, on the edge of the Menai Straits that separate Anglesey from the Welsh mainland. I always have a linguistic compulsion to avoid the bypass and drive along its main street, just to take in the long name outside the railway station.

      Things have changed in Llanfairpwll. During the later decades of the last century you would see navy cadets (of both sexes) walking around the village. They were from the Royal Navy shore-based training school on the edge of the Menai Straits. The name of the school, inherited from a famous training vessel of the past, was on the front of their caps. It said simply Indefatigable. The school closed in 1995, and with it went an era of risqué jokes.

      These days Llanfairpwll has another magnet as well as the name: Pringle’s knitwear store – though its racks of souvenir mugs, books, and teatowels have added fresh nuances to the definition of ‘knitting’. Several tourist buses were lined up outside, and their contents were dancing to and fro at the entrance, excitedly pointing out things in the shop to one another. ‘Hey, you really have to see this!’

      A busload of Japanese tourists was posing for a photograph in front of the long name on the shop and trying to pronounce it. The one at the railway station has a pseudo-phonetic transcription underneath it, which I suppose helps.

      One of the buses was having some difficulty negotiating the turn into the car park, so a small traffic jam built up. While I waited for it to clear, I looked across at the buzzing forecourt. Just inside the door of the shop there is one of those signposts which gives distances and directions to major cities. It tells you that it is 6,879 miles to Buenos Aires that way (past Aberystwyth and keep going) and 5,923 miles to Tokyo this way (via Benllech). It is also 9,898 miles from Llanfairpwll to the South Pole.

      I expect when the tourists get back home they will tell their friends about where they have been, and more will come.

      That seems to be what happened to von Frisch’s bees. When the forager did its round dance, the nearby bees got the message, detected the scent of the kind of flower on the forager’s body, and flew off to look for it. When they found it, they too returned to the hive and did a similar dance. And so it went on, with more and more bees making the visit, until most of the nectar had been drained from the source. Late arrivals at the flower then found little to feed on, so when they returned to the hive they had, quite literally, nothing to make a buzz and dance about. Their dancing movements were slow or they stopped altogether. ‘Don’t bother going!’ And the other bees, noting the inactivity, stayed put – until the next excited forager arrived with news of a fresh source of nectar.

      There was no danger of the Pringle’s source being totally drained. Indeed, as I waited for the traffic to clear, I could see a delivery van unloading fresh supplies. Nectar yesterday, nectar tomorrow, and always nectar today.

      The round dance is enough to indicate the source if it’s fairly near to the hive – von Frisch thought within about 275 feet or so – but if it’s a lot further away, such as a mile or more, something more precise is needed. That’s when the bees do the ‘tail-wagging’ dance. Inside the hive, the forager runs a short distance in a straight line, wagging its abdomen from side to side, then returns in a semi-circle to the starting point. It repeats the run, and comes back in a semi-circle on the opposite side. Then it does the whole cycle again – and again…

      It’s the tempo of the dance that signals the distance from the source. For instance, in one experiment, a feeding dish was placed a thousand feet away, and the bee that discovered it performed fifteen complete cycles of the dance in thirty seconds. When the dish was placed two thousand feet away, the number dropped to eleven. The further away, the fewer the cycles.

      And how do they work out the direction of the food? That’s shown by the straight-line part of the dance. If the dance is done on the platform in front of a hive, in the light of day, the orientation of the bee’s body along the line with respect to the sun is enough to point other bees directly towards the goal. Inside the hive, where it’s dark, the bee’s sense of gravity allows it to make an upwards movement against the honeycomb wall. It’s as if the bee draws a straight vertical line on the wall. If it then runs straight up the line, this tells the others that the food is in the same direction as the sun. If the food is, say, forty degrees to the left of the sun, the run points forty degrees to the left of this line.

      It’s an amazingly sophisticated system, with modifications built in to allow for the sun’s movement across the sky. And it works. When other bees fly out, they know that the nectar source is, say, about half a mile away at a bearing of forty degrees left, and – from the excitement of the dance – how much nectar is likely to be there. And that’s the source they go for, ignoring everything else on the way. In one series of experiments, von Frisch placed other food dishes between the hive and the nectar source that the pioneer forager had found. The other bees flew straight over them, making a beeline, as it were, only for the source they’d been told about.

      The bus that had been causing all the trouble finally made it into its parking bay, but my little traffic jam stayed put. A tractor was trying to follow it in, and that was now blocking the road. What on earth was a farmer doing at Pringle’s at this time of day? As it slewed around, I could see it was pulling a trailer with two sheep in it. Now that’s what I call service. Out of the field, into the Gaerwen auction, and onto a Pringle’s shelf, all in one afternoon.

      I could hear the sound of the sheep above the noise of the traffic. Were there Welsh-English bleatlects? I fantasized about an article: ‘Dialects in the Language of the Sheep’. Von Frisch’s first experiments had used black Austrian honeybees. He then carried out some further experiments using Italian honeybees. The Italians restricted their round dances to distances of only thirty feet. For intermediate distances they performed a ‘sickle-shaped’ dance, which the Austrians did not do. Then, for distances over 120 feet they did the tail-wagging dance, but rather more slowly than the Austrians.

      As a result, when the Austrian and Italian bees were placed in the same hive, the wagging dance of the Italians made the Austrians search for the feeding place too far away. And vice versa. They seemed to understand each other, but not exactly. Just like the dialects of human language, really, von Frisch thought.

      If

Скачать книгу