I'm very sorry about the pics - but these tiny birds are just too quick for me to get a shot of. But I am so happy they're feasting on the mozzies!
First of all we couldn't work out if they were house or sand martins - but after zooming in blearily on the pics - we saw the markings of both.
The house martins spend much of their time on the wing collecting insect prey. Their mud nest is usually sites below the eaves of buildings & they're landing in Gainsborough Schools eaves - so we think they're there. They are summer migrants and spend their winters in Africa.
The sand martins are agile fliers, feeding mainly over water. They will perch on overhead wires or branches - and are landing in the beautiful Sycamore tree along the river.
Do yourself a favour - take a cuppa up to the Purple Garden in the evening after work & marvel at how many mozzies they are sparing us from with their acrobatics.