Before the pandemic, a group of scientists spent a lot of quality time with a group of horses. However, these British researchers didn’t just want to learn more about horses. They wanted to use horses to learn more about zebras and why they have black and white stripes. The scientists obtained fabrics with black and white stripes and draped them over the horses, and then began running tests to see what they could learn about the new colored covering.
According to the published study, “The function of zebra stripes has been a source of scientific interest for over 150 years generating many hypotheses including camouflage, confusion of predators, signaling to conspecifics, thermoregulation, and avoidance of biting flies but contemporary data show that only one stands up to careful scrutiny.”
The authors then discuss a few theories around the zebra’s distinctive pattern.
“Briefly, regarding camouflage, zebra stripes are difficult for lion Panthera leo and spotted hyaena Crocuta crocuta predators to resolve at any great distance making crypsis against mammalian predators an unlikely benefit. Regarding confusion of predators, zebras do not have the sort of striping pattern that aids in confusion and African lions take zebra prey disproportionately more than expected, suggesting an absence of confusion effect.”
However, the use of the zebra’s coloring does more for the animals than just help them fend off predators and protect themselves.
“Regarding social benefits, rates of grooming and patterns of association are no greater in striped equids than in unstriped equids. Finally, there are no thermoregulatory benefits to striping based on controlled experiments using water drums, infrared photography of free-living herbivores , and logical argument in regards to flank striping.”
The study authors added, “there is an emerging consensus among biologists that the primary function of contrasting black and white stripes on the three species of zebras is to thwart an attack from tabanids, and possibly glossinids, stomoxys and other biting muscoids based on laboratory and field experiments with striped materials and on comparative evidence.”
Clearly, the zebra’s coloring serves many purposes. Horses were a great way for the researchers to learn more about the four-legged critter.
“In Africa where zebras live, tabanids carry diseases fatal to zebras including trypanosomiasis, equine infectious anemia, African horse sickness, and equine influenza, and zebras are particularly susceptible to infection because their thin pelage allows biting flies to probe successfully with their mouthparts. The exact mechanism by which stripes prevent flies from obtaining a blood meal is less well understood, however. Flies may fail to detect a zebra from a distance or from close up, either as a result of misinterpreting optic flow as they approach, by interfering with cues that promote a landing response, or even by disrupting the polarization signature of their host. Unfortunately, detailed observations of biting flies in the vicinity of live zebras have so far been unavailable, but such information would help elucidate the stage at which stripes exert an effect on host seeking by biting flies.”
What do you think about this unique approach to studying zebras?
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