I don't know, but birds are small and if you're going to need two to three thousand calories a day to get by (higher in the wintertime), that's a good amount of calories that need to come from sources other than super-lean rabbit meat. Not sure how many calories a bird, like a sparrow, has.

The "rabbit starvation" popped into my mind, too, when the topic of "bunnies" came up. If you (Hacksaw) had to bug out, say, in the winter and you didn't take any food with you, then I suppose it could become a problem, unless you're pretty confident that you could regularly get other kinds of more fatty game in the wintertime, too. What else would you anticipate eating regularly besides rabbit in the wintertime?

Edit: whoops, people already asked my questions while I was typing. Too quick for me!