Windkompensation und Seitenwindkorrektur der Bienen beim Flug über Wasser

Summary

• 1. Bees were trained to a feeding station, where they obtained a 2-mol sucrose solution. The course of flight led across water and covered a distance of 247 m. The speed of the bees and their path of flight were observed.

• 2. When the water surface was mirror smooth, a great number of bees plunged into the water. They continually lost altitude until they crashed headlong into the water, wich thereby flipped them onto their backs. We were unable to observe this phenomenon when the water was rippled or, during smooth water, when the course was marked with a bridge of floating boards.

• 3. The bees always flew slower and lower over rippled water then over solid land or the floating bridge of boards. We measured without wind a flight-speed over water of 6.34 m/s (43 observations), over the floating bridge a flight-speed of 7.93 m/s (11 observations). The difference is significant.

• 4. The bees compensated for the velocity of the wind when flying over rippled water as well as over the bridge, so that their air-speed was greater when they were flying against the wind and less when they were flying with the wind.

• 5. The flight across water was disturbed to a great extent by crosswinds. The bees could maintain the correct angle to the cross-wind only near the banks. When they were farther than approximately 20 meters from the bank, they drifted in the wind. Even the presence of the floating bridge did not help them to hold the correct angle to the wind. The bees were driven across the bridge and followed it in a garland-like track on the lee-side.

• 6. A bee, wich was forced to make a detour to the feeding station did not return by the same route, but chose instead the most direct path to the hive.

• 7. The reasons for a bee flying slowly when close to the surface of the water are discussed.