Is rare duck breast safe?
Rare duck meat is safe to eat because it does NOT contain the same risk of Salmonella as does chicken meat.

Primarily because ducks, as mentioned above, have not traditionally been raised in the same squalid conditions as "factory raised" chickens - salmonella is a disease that is primarily transmitted through dirt/dirty unclean conditions. 

Now, on the other hand, as more and more ducks are being raised in industrial conditions, they are also becoming more likely to contain strains of Salmonella.