[EBB Sightings] white-throated swifts

Dear Birders:

In summers past, well before dawn, I have been aware of the high-pitched 
twitter of what I now recognize as white-throated swifts hurtling by 
overhead.  They sound as if they were flying low perhaps in pursuit of early 
rising insects? I recall reading something on the subject, but can't 
remember where.  Can anyone give me more information?

Phila Rogers