That may seem unimportant. But to phenologists such as myself, it’s evidence of changes in the environment that require close attention. Phenology refers to the timing of annually recurrent biological events: the blossoming of jacaranda trees, for instance, or a mass butterfly migration.
In an article earlier this year, my students and I used media reports to quantify how the timing of the annual butterfly migration had changed over nearly 100 years. The phenomenon has featured in newspaper reports for many years. More recently, with the advent of social media, these butterflies have also been photographed and posted on Instagram, Twitter and other social media platforms.
We also analysed records of rainfall and daily maximum, minimum and average temperatures measured by the South African Weather Service . Though our butterfly arrival date database extended much further back than many of these climate records, we were able to compare the data sets over the period of overlap to determine the role of climate in driving changes in timing.