Chabon's "The Final Solution"

I think they were the serial numbers on the train cars passing to the camps, poignant because probably the only accurate record of which trains/cars made that final trip...although that is only a vague recollection so please anyone correct me.

Laurel's right I think (I thought the ending was a bit confusing as well).
Here's my understanding of the ending (Big spoilers: don't read on if you haven't read the book)

The numbers the parrot was repeating were train numbers repeated by the boy to it in Germany. We work this out when the train in England passes and the boy breaks his silence to repeat the numbers on that train to the parrot. The bad guy assumed the numbers were Swiss bank account codes taught to the parrot by the top Nazi who the boy's father worked for.
Chabon never explicitly says the original trains were concentration camp trains, but as the trains were 'heading east', and the (double meaning)title of the book is 'The Final Solution', that's presumably what we're meant to think.

Hey Joe Kay and Laurel, that makes way more sense.

The whole list of numbers that the boy starts rolling off at the end of the book.... that's where I got lost.

I think Chabon assumes most people can follow a smattering of German.

Good lesson about never assume your readers are bilingual...