you see the body and you see what a raven's done to it, you know, or you see a little pile of hatchling carcasses, you know, it's... you know, we don't...that hurts. narrator: and now ravens are attacking adult tortoises. esque: a few ravens have learned to kill adult tortoises. and so that's just a few individuals right now that are a problem, but each new brood that they are able to produce learns a little bit more from them. and then that's how we get t populations that change their behavior. mullen: so you get an adult tortoise that's finally at breeding age, that's a really valuable commodity: a breeding adult. and every one of those is precious to us now. so it's a different situation than it used to be. narrator: today numerous agencies are coordinating research into tortoise behavior and the relationship between the tortoise and its environment. lovich: this is a male, so it wouldn't surprise me that he made a spectacular movement. narrator: this study is being conducted on a wind farm just outside of palm springs, california. tortoises spend much of their time in burrows and may use more