Warblers, Chaffs and Blackcaps

Whilst carrying out my regular 'kite nest watching' at the end of last week and today, I was struck by the larger number than usual of Willow Warblers, Chiffchaffs and Blackcaps to be seen this year. Is this a real phenomenon or am I just seeing more as they are more visible because of the late season, with fewer leaves on the shrubs and trees?