Last Sunday I realised to my dissapointment that I had not cracked the geaden warbler/blackcap song split as I had hoped. I know the "classic" blackcap starts scratchily and then builds up to a purer climax and is of relatively short duration and moderate tempo, whilst the "classic" garden is faster, somewhat breathless, longer and less changing in timbre. On Sunday I listened to a bird over a period of time which did not precisely fit either. Fairly short fairly hurried, maybe slight change in purity towards the end but nothing obvious. Is there any definitive feature to listen out for that splits these two?