I live in South Lincolnshire and have kept a nature diary since the 22nd November 1959 and in most years I have recorded the arrival and departure of Swallows here in South Lincolnshire.
Arrival dates have been gradually getting earlier about one week earlier over the past 50 years and I suppose that can be expected being as our climate is warming up.
Every year until the late 80's I could see Swallows until around the middle of October but during the past twenty years they have been gradually leaving earlier until over the past few years they leave soon after the middle of September.
I estimate that Swallow numbers have declined by at least 80% in the past 40 years and I put that down mainly to the reduction in cattle numbers. There are now no cattle within two miles of where I live. I also know that there are less insects in and around our crops.
According to my nest records I know that Swallows in the 1970s and 1980s in South Lincolnshire fledged their first brood during the second half of June and their second brood in August. In the last few years Swallows in this area have fledged their first brood in July and their second brood in the first half of September.
Insect numbers have declined in South Lincolnshire. When I was a boy I can remember there being many flies, possibly up to 100 in our kitchen but today if there are three or four, that is all, and that is still too many for my wife. The front of my car used to be plastered with insects during the summer, now it doesn’t have half so many insects stuck on it.
With 20 million vehicles on our roads acting as fly swatters and every time our crops are sprayed we are either starving or killing insects, cattle and sheep are treated with insecticides to reduce parasites which reduces the amount of flies around them and in every walk of life 95% of people are at war with insects so we are bound to have less insects around.
Swallows tend to nest in the arches of houses and often they are removed by home owners as they can be seen as a mess (due to the bird droppings). Unfortunately removing and disturbing their nests are helping the Swallow population to decline, my suggestion to help prevent this decline is to purchase and install a bird box to re-home these animals.