Swallows

During the intense heat this week the swallows were behaving in an interesting way in the Holkham Walled Garden by clustering and chattering in groups of up to twenty in a tree and then swooping over to  flatten themselves against the hot wood of the high vinery. The sunbath would last a few moments and then whoosh! they were off again back to the tree in the garden,  backwards and forwards they went. The behaviour appeared rather odd but was entertaining. 
Perhaps they are having a last week or two of play before setting off for their long journey south. The RSPB website explains: 
"Swallows arrive in the UK in April and May, returning to their wintering grounds in September and October.....British swallows spend their winter in South Africa: they travel through western France, across the Pyrenees, down eastern Spain into Morocco, and across the Sahara. Some birds follow the west coast of Africa avoiding the Sahara, and other European swallows travel further east and down the Nile Valley. Swallows put on little weight before migrating. 
They migrate by day at low altitudes and find food on the way. Despite accumulating some fat reserves before crossing large areas such as the Sahara Desert, they are vulnerable to starvation during these crossings. Migration is a hazardous time and many birds die from starvation, exhaustion and in storms. Migrating swallows cover 200 miles a day, mainly during daylight, at speeds of 17-22 miles per hour. The maximum flight speed is 35 mph.