Benefits of zebra stripes
The function of zebra stripes has been of interest to scientist for over 150 years. Many hypotheses have been proven to be untrue, for example: a function in thermoregulation, social benefits or confusion of predators. However, there is an increasing consensus among biologists that the function of black and white stripes is to avoid attacks of horse flies.
In Africa horse flies can carry diseases lethal to zebras. Therefore, zebras can avoid getting bitten have a fitness advantage. However, the mechanism by which stripes keep off horse flies is unknown. The aim of this study was to compare the behaviour of horse flies between captive zebras and domestic horses, as well as around horses wearing differently coloured blankets.
Three captive plains zebras and eight uniformly coloured white, grey, brown and black horses were studied in the UK. The horses and zebras were kept in adjacent fields and film was made of horse flies in the vicinity of the animals. In addition, three different blankets were put on the horses randomly for 30 minutes. One blanket was dark black, one was bright white and one was irregularly striped.
Observations show that fewer horse flies landed on zebras than horses. The number of horse flies circling around and briefly touching zebras and horses did not differ. In addition, horses wearing a striped blanket had less horse flies landing on them. In conclusion, up close, striped surfaces prevented flies from making a controlled landing but it did not influence that behaviour of flies at a distance.
> From: Caro et al., PLoS ONE 14 (2019) e0210831. All rights reserved to Caro et al.. Click here for the online summary.