Thought this group might be interested to know that over the past few days
there has been an unprecedented arrival in the south of the UK of some
summer migrants...House Martins, Swallows Sand Martins and also continental
butterfly species.
All these bird species usually winter around the Saharan region though a few
may stay further north, but usually don't start to appear for at least
another month to six weeks time.
Being quite interested in the effects of weather on bird migration I
wondered if any of the experts may be able to point out any possible
meteorological causes of this highly unusual activity?
It is quite common in Spring for a wave of migrants to arrive with a push of
warm air from Europe and Africa, but this early in the year is highly
unusual.
Any thoughts?

J Poyner.