They're also kind of expensive compared to mice, and while you could breed your own, they're smart, aggressive, and excellent escape artists. (I will say that they smell less than mice-they're desert dwellers by nature, so they have very dry droppings, and tend to use one part of the tank preferentially). Unless you're feeding desert-dwelling snakes, it's not going to be a normal food source-the Kangaroo rats and Jerobas in the SW are similar animals, but the gerbils sold in the US, for the most part, are from lines from the Mongolia Steppes, which is pretty far removed from our corn snakes. The hair is stiffer than mouse hair, too, so I could see it being harder to digest (and, they have those thick tails, compared to mice-basically, it's a long column of bone, covered with fur, and not terribly bendy or agile-the tail is mostly used as a stiff rudder for balance).
I've also seen gerbils fight and kill each other quite readily-I'd be very, very nervous about feeding one live to a snake for that reason.
--Donna (who went through several years of attempting to breed gerbils as a kid when they were a new thing in the area).
