Cabbage White Butterflies in Mating Dance?

 

At the end of August, I spotted these cabbage white butterflies (large whites, I think) participating in what appeared to be a mating dance. I took the video on my Pixel 4a phone so the quality is not great. See here for a higher-quality close-up video.

Cabbage White butterflies can see in the ultraviolet (UV) range of the electromagnetic spectrum which helps the male identify females from the UV reflections on the female's wings. Hence the fluttering display of the butterflies.  According to this 1970 research paper, this ultraviolet communication system enables the identification of suitable mates and the initiation of courtship leading to acceptance or refusal of mating behaviour by either sex.

I thought it interesting the butterflies kept landing on the patches of homemade sieved compost rather than the natural soil. Whether there is some attractant in the compost or it is the broad bean seedling germinating under the compost, I haven't the foggiest.

Cabbage Whites are the dominant butterflies at the present time - late summer to early autumn.