Mystery ducks on Lake

Murray Head sent the two photos above and the following query yesterday:

Hi Marie, I espied this graceful pair of (?) gliding swan-like about The Lake. Interesting markings... perhaps he is wearing a yarmulke? Could you identify them? TIA, Murray 9/4/10

The first challenge: what does TIA mean? Thanks In Advance is my best guess, though I've never heard the acronym before.

Now on to the ducks. Well, they must be some kind of domestic duck, I figured, and headed for the Internet . It never fails. There, at a site for Kintaline Farm in Argyll, Scotland, I found a fairly close match: a magpie duck, they call it, a breed that seems to produce a lot of eggs and plump meat. But how did those Scottish ducks get to Central Park? That's the next mystery.

PS There is much variety among domestic ducks..