Canadian, living in Canada and receiving US SS and CalPers retirement income.

My wife is Canadian, living in Canada and receives US SS and CalPers retirement income.  I'm a US citizen also recieving SS and living in Canada.  I know I have to declare my World Wide income in the US, but what does my wife have to declare?  Specifically, does she have to include Canadian income as well as her US income?  Also, can we file jointly if she only declares her US income and not her Canadian income?