[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2011]
In nature, predators know that bright colours most likely mean danger. But it may not be the striking stripes of bumblebees that warn predators they are dangerous.
Flying predators, such as birds, are the biggest threat to a bumblebee. It may seem like the colour markings of bumblebees are solely responsible for their defence; but their shape, flight pattern and buzzing sound should probably take more of the credit.
Birds view the world differently to us. They are able to see a range of light in the ultra-violet spectrum. Because the white tip of the bumblebee’s tail reflects ultra-violet light, it is very obvious to birds, as are their bright bands.
New research involved comparing different bumblebee populations in the same environment, each with different colour patterns. If colour patterning in bumblebees is important in alerting danger, then birds would have eaten bees they had not previously encountered, therefore avoiding a nasty sting. This, however, was not the case.
So what is it then that acts as the warning bell to the bird predators? Scientists found that the way in which bumblebees fly as well as their deep buzzing sound are more important for birds in order to avoid danger.
Even though colour-pattern recognition plays a role in identification, it seems that birds do not initially notice this in the split-second when a bumblebee passes. A bumblebee’s combination of sound, flight and colour acts as a warning bell to their flying predators.
Interesting fact
Bumblebees, like birds, also see in the ultra-violet range of the spectrum. This comes in handy when detecting ultra-violet markings on flowers, invisible to the human eye.
Source: Royal Holloway, University of London (2010, May 29). How do bumblebees get predators to buzz off?. ScienceDaily.
Viewed online [http://www.sciencedaily.com¬ /releases/2010/05/100526093608.htm]