IGN has managed to get a hold on the Art of Titanfall book ahead of its release next week, and some of the things they found inside are... interesting. Including a mention of monsters that indicate some large wildlife could appear on one of the maps.
IGN says the book confirms the name of some of the datamined maps folks dug form the game's beta files this week. It also shows some pilots fighting some flying beasties and some larger scale creatures walking around, asserting that in the final game, some animals "will walk or fly around levels harmlessly until people interfere. Others will attack when you just stare at them."
It also refers to some non-Titan vehicles like drones and tanks. Much more in IGN's videos they've posted of them flipping through the art.