Why does the Rutan Voyager use canards? Can anyone point me to why Burt Rutan's Voyager is a canard? 

In other words, what reasoning could be behind it. What problems Burt Rutan might have tried to solve by using Canard configuration in this specific aircraft
and why those problems may not be solvable or less feasible in a conventional configuration?

For  comparison I would prefer to use predator or global hawk.

I believe this is because noticeable CG shift during flight and possibly has some advantage in relation to dynamic responses.

But I would like to get a second thought from you guys.

PS: English is not my mother language so apologies in advance if Im not clear enough. Unfortunately the answers I've got so far are either not very well thought or incorrect.
The canard is a design which stabilizes in front but also adds lift, whereas elevators at the back actually subtract lift.  As the Voyager needed to take energy efficiency to the extreme, this would be a prime design choice.  His motivation may be in the book written about the Voyager, but a significant number of his designs were canards.