[palapiku]

All white-crowned sparrows around Vancouver and Richmond sing exactly the same song over and over again. The only variation I've noticed is that occasionally some sparrows stop halfway through.

This one from north-central Richmond is quite different:

https://dl.dropboxusercontent.com/u/9782976/sparrow.mp3

As I understand, white-crowned sparrows learn their song from their neighbours, which is why all songs in an area sound the same but there's large variation between different areas. Could this be a migrant originally from a different area?

[esle9]

That does sound a bit different.
Earlier this month I went on a trip to Portland with my school band. We took a bus, and every time we stopped I would here White-crowned Sparrows singing a slightly different song from Vancouver, until the songs were completely different. Then in Portland, I heard a sparrow singing a perfect Vancouver song!
I've also noticed a sparrow outside Nat Bailey Stadium/Little Mountain Neighbourhood House that sings his song with the second note one tone off from normal.
I think it's definitely possible your bird is a migrant from another area, or maybe he wasn't exposed to the proper song early enough. Or maybe he is just "creative", after all, the geographical dialects and variations in bird song had to start somewhere.