The other local garter snake, the red-sided (T. sirtalis parietalis), I've never found around the house, possibly because we don't have water nearby. Both species can be found in aquatic habitats, but I suspect the red-sided is more water-dependent. If I get out fishing anytime soon, I'll try to photograph a red-sided for comparison.
One of my redtails, Pocomoke, was a confirmed ophidiovore. We hawked rabbits (or attempted to) well into March, but on warm days he vastly preferred to fill up on snakes, especially garters. (I brought Pocomoke to Nebraska from Georgia, and since he was trapped in the aftermath of a hurricane and later moulted into an unusually colorful plumage, I always suspected he might be a Florida redtail, Buteo jamaicensis umbrinus. Sub-tropical origin might have accounted for his taste for serpents.) Anyway, I'm glad that our yard (including the area around the mews) can serve as a refuge for these beautiful reptiles.