It is so unusual for there to be so few migrants, for such a prolonged period of time, in August at this site. When considering the reason why, there seems to be some merit in the comments being made by other ringers around the country that Blackcap numbers seem to be below what we expect to see in an average year.
It may also have something to do with weather patterns, not only unseasonal conditions in the UK, but also it may be something to do with the unusually high, extreme temperatures in Southern Europe, being driven by a 'heat dome' where heat gets trapped over a reason for days or weeks. This has also resulted in wild fires in several areas.
Alternatively a contributing factor to Broadwater's lack of migrants may lie closer to home. Disturbance due to HS2 work that has not only cleared vast swathes of vegetation, but also includes the sound of the relentless pile driving that creates noise pollution and vibrates through the earth to a considerable distance
Total: 30 (3)
Robin - 2
Dunnock - 1 (1)
Blackbird - 2
Blackcap - 6 (1)
Chiffchaff - 6
Willow Warbler - 4
Long-tailed Tit - 0 (1)
Blue Tit - 5