How variable is Cetti's Warbler song?

[Tursiops2]

All the Cetti's I've heard go:
"chuwee! chuwit, choowy-oowy-oowy-oo!"
(or something like), but this last week or so I've been listening to a bird that seems to have settled in at Levington Creek, with a song that's oddly different - more:
"chwit... chirra-chirra-chirra-chirra-chwit!"
The tone, pitch and volume are all Cetti's, but the pace, structure and rhythm a more like a Great Tit.

Is this just natural variation between individuals, a first-year bird getting into practice, or something else?
T2

[ChrisJB]

They are indeed variable Tursiops, but usually not so variable that you think it might be something else in my opinion! I've heard variations in the field, though not all four examples of song that it plays on my birdsong/call C.D.
Hope this is of some use.

Regards, Chris