SWALLOW (Hirundo rustica)
Common throughout Switzerland this bird is often called in English "Barn Swallow" due to its habits of building its little cup-shaped mud nest in farm buildings, and just about every farm in the low valleys of Switzerland has its pair of resident swallows in the summer time. From late March until late September they can be seen hawking after the flying insects that make up their diet, swooping and turning in the chase using their long tail streamers as rudders.
Their pretty little song is delivered usually from a favoured perch not too far from the nest, but in the spring potential pairs can be seen in high-speed aerial chases, I believe with the male doing the chasing (as usual !) when he may also reinforce his vigour by singing as well:
The song is a series of pleasant twitterings with the occasional phrase finished off by a very rapid "burring" noise and a series of clicks as in this example: