San Angelo State Park consists of lake habitat, rocky hillsides, mixed woodland river bottom and mesquite savannas.

Over 300 species of birds, 50 species of mammals and 42 species of reptiles have been observed at the park.

Mesquite brush inhabitants include Verdin, Pyrrhuloxia, Canyon Towhee, Greater Roadrunner, Curve-billed Thrasher, Scaled Quail, Northern Bobwhite, Vermilion Flycatcher, Chihuahuan Raven, Cassin's and Black-throated Sparrows and Cactus and Bewick's Wrens.

Summer nesting birds include Yellow-billed Cuckoo, Mississippi Kite, Swainson's Hawk, Bell's Vireo, Orchard and Bullock's Orioles and Yellow-breasted Chat.

Winter and migrations are the best viewing times for birders, as the migrating shorebirds and waterfowl can be seen when O.C. Fischer Lake has had rainfall. Expect to see a wide variety of ducks, as well as other winter visitors, including Franklin's and Bonaparte's Gulls, Forster's and Black Terns, Osprey, Northern Harrier, Western and Least Sandpipers, Sora and Greater and Lesser Yellowlegs.Migrating shorebirds such as Pectoral, Stilt, Spotted and White-rumped Sandpipers can also be seen. 

In the woodland areas, expect to find a good mix of woodpeckers such as Northern Flicker (Yellow-shafted and Red-shafted), Yellow-bellied and Red-naped Sapsuckers and an occasional Acorn or Red-headed Woodpecker. Say's Phoebe can occur along the water's edge, along with wintering Swamp and White-crowned Sparrows.