Flying Ant Day: fact or myth?

Flying Ant Day: it has the ring of a 1960s Hammer Horror. Scores of ants sprouting wings and taking to the skies on a single day, causing nation-wide dismay. The idea of a single mass flying-ant event each year is ubiquitous. But is it true?

Thomas Hesselberg, Director of Studies for Biological Sciences and Course Director for the Deparment’s Postgraduate Certificate in Ecological Survey Techniques, took part in a study that used citizen science to investigate the phenomenon of ants’ flights. The inclusion of citizen scientists enabled the team to amass the largest sample size to date of winged ant behaviour – and provided answers where previous studies had been inconclusive.

Nuptial flights

Most species of ants produce winged males and queens who embark on ‘nuptial’ flights for the purpose of mating and establishing new colonies. 

Previous research indicated significant synchronicity in these flights, and also that weather played a part in the ants’ behaviour. But the usefulness of previous studies was limited by small sample sizes.

To really gauge what the ants were doing – and when – required more people in more places, all observing the ants’ behaviour at the same time. A massive undertaking, made simpler by harnessing the power of the public.

Over the course of three years, beginning in 2012, citizen scientists from all over the UK gathered more than 13,000 winged ant observations – creating the largest dataset to date.

Dr Hesselberg, who analysed the collected data, said: 'This study demonstrates the significant contribution that non-scientist can make to ecological studies. In this case by in unlocking some of the secrets behind nuptial flights in ants. The very large data set allowed us to use a number of sophisticated statistical techniques to analyse the data from both a spatial and temporal perspective that had not been possible on smaller and more limited data-sets.'

Flying Ant Day: fact or myth?

And the findings? The notion of a single day in which all the ants rise up into the skies, or 'spatiotemporal synchrony', turns out to be myth – stuff best left to film producers.

Ants were flying on as many as 96% of days between the start of June and the start of September. It was clear that most activity took place in July/August, and that regional activity followed the warm weather, as summer progressed northwards. 

The ants also proved themselves adept at short-range weather forecasting.

Ants were shown to prefer warm, windless days. Every day in summer with a mean temperature above 25C had ants flying somewhere, and it was shown that if the weather were set to improve, ants would wait for optimal conditions. Conversely, If the time was ripe but the weather was deteriorating, the ants would fly so long as the temperature rose above 13C and the wind speed was less than 6.3 metres per second.

Based on the data, study authors Adam Hart and Anne Goodenough (University of Gloucestershire), Thomas Hesselberg (University of Oxford) and Rebecca Nesbit (Royal Society of Biology) were able to reach the following conclusions, accepted this summer for publication in the journal ‘Ecography’:

  1. spatiotemporal synchrony in flights is lower than previously thought 
  2. local temperature and wind are key predictors of flight phenology; and 
  3. ants appear able to determine, at least in a limited way, if weather is improving or deteriorating and adjust their behaviour accordingly.

The public reaction to a swarm of flying ants is never going to be 100% rosy – but the next time you encounter them, be aware that both you and the ants made the decision to get out and about on a nice summer day, and that you are witnessing one of the great spectacles of nature.

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Published 11 September 2017