If in the redwood biome run to one of the small streams they glitch and don't register as water for you but it does for the terror bird so you can go prone in those streams and the terror bird will lose agro works for carno to.
I hate them with a passion like no other. Fast, travel in groups, very aggressive and strong attack means these things won't hesitate to make a meal out of you. All over SE and heavily concentrated in the Red Forest on The Center. If you can outrun them, (higher level = faster bird) best thing to do before you run out of stamina is introduce them to their oversized cousin the paracer. Stand by it's legs and let the bird try to attack you. I will accidentally bite the Paracer and make it angry. Immediately move out of the paracer's legs and run forward then across the path of the paracer again as the bird won't de-agro off you till it takes damage from the Paracer. If the paracer is anymore than 20 levels below the bird, or if the bird has friends, run like hell! If not, wait and the Paracer will kill it for free meat and hide and often some items, as they carry them usually. Same idea works with wolves, cats, etc. You can also run them into other defensive dinos or their fav snacks!
This thing will aggro on most dinos you knock out. Me and my buddies were taming a 150 Rex, on Ragnorack, in a taming pin, and right when it got close to 98%, one of these douchebags ran past THREE Tribemates and ran STRAIGHT to our Rex to nibble on his nose. He lost 15 levels on Taming that day. Our Tribe member taming the Rex was speechless. Then we let the Rex eat the Terror Bird's corpse. It was a good day.