Gravity disturbs bees' dancing
Honey bees that dance to give directions to flowers make more errors when performing horizontally due to gravity, say researchers.
Female foragers perform "waggle runs" on the hive's honeycomb for other bees.
The intricate movements display the direction and distance of the flowers from the hive.
Researchers from the University of Sussex are "eavesdropping" on bees to find out more about where they feed in Britain.
Dr Couvillon decodes angles in the dances by hand
Dr Margaret Couvillon has spent three years decoding the bees' unique method of communication.
Using observation hives with a glass wall, researchers have filmed the bees without disturbing their natural behaviour.
In honey bee society, forager bees scout out flower resources and return to the hive to perform a detailed dance made up of "waggle runs" on the honeycomb that communicate direction and distance.
The angle the waggle is performed at communicates the position of the flower relative to the sun, while the duration of the waggle tells nest mates how far away the flower is from the hive.
Foragers repeat these runs in a figure of eight with the number of repetitions signifying the quality of the resource.
"For a really good resource she'll repeat it 70 to 100 times," explained Dr Couvillon.
By studying the video footage, Dr Couvillon found that bees dancing vertically on the honeycomb made few "errors", repeating identical runs throughout the dance.
But bees dancing on the horizontal had more scattered runs.
"They have a hard time when they're dancing horizontally - the angles that they dance repeatedly are very different," Dr Couvillon told BBC Nature.
She explained that due to these errors a more holistic approach was needed to understand the message contained in horizontal dances.
Although the individual runs contained errors, an average calculated from all of the runs still provided accurate directions.
Dr Couvillon suggested that the inconsistencies could be attributed to gravity; when the bees are vertical on the comb they are aligned with the downward force but dancing horizontally requires more effort.
"If you were a rock climber and I asked you to get something to your right, at 90 degrees, it would be more difficult than getting something straight ahead of you," she explained.
The results feed into an ongoing debate in the scientific community over whether the variation in waggle dances happens because bees are communicating a general area, not a specific flower, or simply because they are trying their best in difficult circumstances.
"There's no reason why a bee would need to introduce scatter into a dance," said Dr Couvillon.
"I do think the bees are challenged but I still think they're pretty good at what they're doing."
Ella Davies, BBC Nature