[QUOTE 2408442, member: 9609"]Apparently when you walk over cut grass you disturb flies etc and they take off, swallows have cottoned on to this and frequent parks and golf courses etc for this easy source of food.[/quote]
Indeed. Many years ago I spent a month (September) hop picking in Kent and dozens of swallows were feeding in preparation for a long migration. Large flying insects, disturbed by us from their habitat, were easily eyed, pursued and eaten in the twinkling of an eye by the swallows. Fantastic flying skills, they have. And, needless to say, navigational skills, too.