Rockstar put up a fan made find of Trevor appearing characters around Los Santos/ Blaine County, I doubt the intent was this to be multiple Trevors in reality, but as Aaron Garbut explained a long time ago, with GTA IV, Ped Packs are created for the current gen games, and then dressed and altered slightly, so there is certainly a possibility of finding more then a few doppelgangers.
As far as animal variety, notice there's no horses either? I see some stables that are curiously empty, and a horse race track.
There are deer, as we'd seen in the trailer, in fact, the wild boar were a surprise, but take note as well, they can actually go up stair cases! Saw them wander the hallways of the abandon hotel near the chair lift to Mt. Chiliad (Yep, I've been spelling it wrong....my bad)
There are chickens as we also saw in RDR, if I recall, they aren't too plentiful.
Edited by BlackListedB, 25 September 2013 - 10:49 PM.