Originally Posted by NewChief
It's a zombie herd. It's part of the comics. Zombies mimic other zombies. One zombie moves off with purpose for some reason, then others join in, then more and more. This herd has been walking for who knows how long? It's probably not a group of "local" zombies who have been lurking around in the area forever just waiting for the right moment. We saw a smaller migratory herd that passed them all on the interstate scene at the opening of season 2. Now, it's somewhat unrealistic that this massive zombie herd just happened to run on a collision course with the farm, but that doesn't particularly bother me.
The whole Rick and Shane walking all night then having their showdown close to the homestead did bother me, though.
It looked like it could be a zombie herd of around 50+. If people recall at the beginning of season 2 they showed a zombie herd of around 100. In the comics, the herds can reach the size of thousands.