There is no set timeframe. Swans sometimes include copulation in their pre-nuptial bonding dance without actually transfering sperm. Just before the pen lays, the cob becomes extremely aggresive.
As a general guide, reckon on one week but this can vary greatly.
Thanks a lot wildwood (I thought you might answer this), I'll pass the info on to my sister, they've got a narrowboat & she saw a pair getting busy last weekend...must have been the sunshine. She thinks they might be the same ones as last year, they had a lovely family of four & there was always one hitching a ride on dad's back :o)
The site where I normally walk Max has a pond and the femail of the resident pair of swans has been sitting her eggs for about 3 weeks nobody I've talked too can give an accurate count of how many eggs shes' got but hopefully in 2-3 weeks we'll have some cygnets on the water
That's Max when he was 10wks old, (he's now 8 yrs) and he was helping to decorate, he'd already started to strip the wall paper in the hall, and then moved on to carrying the dusters, brushes, in fact eveything we were using to where he thought we really needed them usually in his basket