A Sting in the Tale by Dave Goulson Page B

bees to return, eagerly looking at each incoming bee to see if it was one of those I had released.
    Some I released within 1 kilometre of my house, and more often than not these bees would beat me back to the nest. Even from 2 or 3 kilometres the bees would often be back within a few minutes, while I got caught up in the usual Southampton traffic (bees don’t have to worry about such things). From further afield, it took rather longer. I released bees up to 15 kilometres from my house and sadly none of these ever returned. I like to think that they had a nice life, freed from the burden of work in the nest, and enjoyed themselves. Perhaps they found a different nest of their species and tried to lay some eggs in it (something that worker bees sometimes do). I am probably kidding myself. Whatever happened to them, I never saw them again.
    The record distance over which a bee successfully returned to the nest was 10 kilometres. I was very proud of Blue 36. It took her two days to get home. Between 3 and 10 kilometres the number of bees that made it back steadily declined, and some would take up to three days to return to their nest. White 15 was released next to a nice patch of borage flowers in the grounds of Chilworth Manor, about 3 kilometres from my house. Borage produces particularly large amounts of sweet nectar, which both honeybees and bumblebees love (the flowers also make a colourful addition to salads, and the leaves are considered by some to be an effective cure for premenstrual tension, should you need any other reason to grow some). I happened to be doing some other experiments with bees on this patch of flowers, and was returning to them at regular intervals when not transporting bees around Hampshire or sitting by the loft waiting for them to return. White 15 was one of the clever bees that made her way home successfully and swiftly, but to my amazement on subsequent days she went back to the borage flowers. Every evening she was in her nest in my garden, but she would spend her days repeating the 6-kilometre round trip to Chilworth over and over again to collect nectar.
    What can we learn from all this? Firstly, that bumblebees have pretty amazing navigational abilities. Scale the feat up in proportion to size, and Blue 36’s feat is equivalent to a man being taken about 1,600,000 kilometres from home and managing to find his way back again under his own power. This is more than four times the distance to the moon. White 15’s repeated journey to Chilworth to collect food is the equivalent of a man circumnavigating the globe ten times just to get to the shops – and then having to come back again – several times a day. Perhaps these comparisons are a bit silly, but it is hard not to be impressed.
    So how do bumblebees find their way home and, more generally, how do they navigate? This is hard to study – after all, they are small and move fast, so it isn’t possible to watch. Some clues may be gleaned from observing how a worker bee behaves when she first leaves her nest – the behaviour is very distinctive. She usually flies out just 20 or 30 centimetres, and then turns to face back towards the nest entrance. She hovers from side to side, and sometimes flies a few small loops around the nest, not going more than 2 or 3 metres away. She is probably memorising the entrance to her nest, fixing the relative location of any obvious landmarks in her tiny brain (sticks, tussocks of grass or whatever). If she flies out and cannot find her way back in, then she can never bring food to the nest – and given that her role in life is to help her mother rear more of her siblings, this would be a disaster. After a few moments, she ventures off and is lost from sight, but she usually returns soon afterwards, and repeats this several times before disappearing off for longer periods. After a little while she then settles down into foraging, flying purposefully from the nest, and reappearing