A team from the University of Freiburg led by neurobiologist and behavioural biologist Prof. Dr. Andrew Straw studied the flight behaviour of honey bees. Using a drone, the researchers tracked honey bees as they flew between their hive and a food source about 120 metres away in an agricultural environment. In order to observe the bees on their respective routes, the scientists used the 'Fast Lock-On (FLO) Tracking' method developed by Straw's working group. This involves attaching a small, highly reflective marker to the insect. On the drone, a computer uses image analysis of reflected light to reliably locate the bee within a few milliseconds and keep track of it. The results show that each honey bee navigates in its own unique way and maintains these individual routes with the utmost precision on both the outward and return flights. The animals use landmarks in the landscape as orientation aids.
"Our tracking system makes it possible for the first time to record high-resolution 3D flight paths of honey bees in natural landscapes," explains Straw. "Our recordings show that each bee has its own preferred route and flies it very precisely. You could almost say that each bee has its own personality."
Bees use their environment to navigate the world
The 255 flight paths analysed were obtained near the Kaiserstuhl, Germany, in an agricultural region containing hedges, a cornfield and a tree blocking the direct route between the beehive and the food source. "We found a high degree of precision in the flight paths. Individual bees repeated their individual flight paths nearly exactly on several flights. They often fly just a few centimetres away from their previous paths," Straw emphasises.
The team identified the smallest deviation in the flights near prominent landscape features such as the tree. In contrast, the greatest variability was measured above the cornfield, an area with a very uniform visual structure. "Our results suggest that visual landmarks aid the bees' navigation and increase the precision of their flight paths," explains Straw. In contrast, the bees' uncertainty increases in visually monotonous environments.
More precision than in the waggle dance
The study also provides new insights into the interpretation of the waggle dance, which honey bees use to indicate the location of food sources to their fellow bees. "It was previously known that the directional information in the waggle dance is not entirely accurate," explains Straw. For food sources approximately 100 metres away, the directional information in the waggle dance can deviate by around 30 degrees. "Our research has shown that individual bees navigate much more accurately to destinations they are familiar with. Even where their flight paths vary most, they deviate from their individual route by only a few degrees. Our results allow us to conclude that the inaccuracy of the waggle dance is not due to the bees' limited navigational abilities. Rather, individual animals are spatially much more accurately oriented than their dance communication would suggest," says Straw.
