Eclipse

Next month, a total solar eclipse will briefly plunge the South Pacific, Chile and Argentina into darkness, but how will wildlife react to this astronomical event?

- Jamie Carter

There is no more powerful nor more fleeting a sight in nature than a total eclipse of the sun. For humans standing in exactly the right place, this is the only time when the sun’s outer atmosphere, the ice-white corona, can be seen with the naked eye. It can be an amazing, emotional spectacle, but how do animals and insects experience it?

On 2 July 2019, a total solar eclipse will plunge a 145–193km track of the South Pacific, northern Chile and Argentina into blackness for just over two minutes. Witnesses to the rapidly darkening landscape during a total solar eclipse have always observed wildlife, though, mostly, it’s been anecdotal. As the sky turns twilightlike, stories abound of birds going to roost, dairy cows returning to the barn, croaking frogs, flying bats and crickets making a cacophony of noise. Such reactions suggest a change in behaviour but, until recently, there’s been little measurable science. That all changed on 21 August 2017 when a total solar eclipse swooped across the USA. It was a rare chance to study the effect of totality (when the sun is obscured) across a large landmass and, since the USA has much advanced and consistent weather and radar data, scientists had far more information than usual, to help them design their studies.

Back to black

An eclipse is not like a sunrise or sunset, which occur before and after prolonged twilight. A total solar eclipse – which takes place roughly once every 16 months – brings sudden darkness, along with reduced temperature and wind speed. The profound gloom lasts as little as a few seconds and as long as seven and a half minutes – depending on the observer’s exact location – but it’s often a once-in-a-lifetime opportunity for researchers to see how their chosen field of study is affected by the event.