Zebra stripes confuse biting flies, causing them to abort their landings

Zebra research

Zebra research

An worldwide research team has explored the issue further, seeking to discover what it is about the stripes that actually disrupts a biting fly's ability to land on a zebra and suck its blood? UC Davis Professor Tim Caro led a series of unique experiments for this study to better understand how stripes manipulate the behavior of biting flies as they attempt to come in for a landing on a zebra.

To prove their point, the academics dressed up a domestic horse as a zebra, to show fewer flies land on them. They use their tails to bat them away and, when flies do land, they don't stay long because zebras move around a lot.

"Horse flies just seem to fly over zebra stripes or bump into them, but this didn't happen with horses".

So, as JoAnna Klein reports for theNew York Times, a group of researchers headed to a farm in Britain where domestic horses are kept alongside zebras that were born in captivity. Today, many scientists believe that the black-and-white stripes actually function as a fly repellant, but because it's hard to get close to wild zebras, it hasn't been clear how the pattern might deter the pesky critters from landing on the animals and taking a bite.

It's one of nature's more intriguing and enduring mysteries: Why do zebras have stripes?

To confirm that it was indeed coat pattern that was thwarting the flies' precision, the researchers kitted some of the horses out in three cloth jackets: one white, one black and one zebra-striped. In Africa, flies called horse flies carry diseases that may seriously harm zebras so they have developed the stripes to protect themselves.

There had been four main hypotheses about the advantages zebras accrued by evolving stripes: camouflage to avoid large predators; a social function like individual recognition; thermoregulation, with stripes setting up convection currents along the animal's back; and thwarting biting fly attacks. Zebras swish their tails nearly continuously during the day to keep flies off, stop eating when flies bother them, and run away if the flies are particularly persistent.

Scientists conducted an unusual experiment involving zebras and horses dressed in black and white striped costumes.

The bugs were still attracted to the zebras, and still pursued them from a distance, but couldn't nail the landing when they got close. Zebras exhibited preventative behaviour, such as running away and tail swishing at a far higher rate than horses.

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