The humidity changes after a good downpour of rain and this is the best time for flying termites, known as alates, to wing their way out of the nest and go in search of a mate and a nesting spot. Termites are very delicate creatures with a very thin exoskeleton, so they live longest out of the nest when the air is warm and humid.
However, this mass exodus provides a termite feast for hawking insectivores that swoop down and catch them on the wing. You often see much bigger birds, even eagles, standing above a termite nest and picking off the alates as they emerge. Even some small mammals help themselves to the buffet.
These barn swallows (Hirundo rustica) were gorging themselves and provided an aerial show that was a treat to watch and photograph. They were wheeling around in great numbers and each flying off with an alate in its beak.
No doubt many alates got away, as they do every year, and will go on to form new colonies and do the extremely important work they do, which includes processing plant matter that results in increases soil fertility by adding nutrients back to the soil and aerating it.