The Greater Roadrunner (Geococcyx californianus) is a widespread predatory bird in the southwestern U.S., but its nesting and behavioral ecology remain understudied. In 2015–2016, we used infrared cameras to examine its nest defense behaviors. Nest predation was the sole cause of nest failure, with Great Plains rat snakes (Pantherophis emoryi) responsible for 70% of cases. Roadrunners defended nests against snakes in 53.3% of encounters but not against coyotes, likely due to predator size. Defense sessions lasted 1 min 20 s, with 12 bill strikes per minute. While no nest was fully preserved, over 50% of defended nests retained at least one viable egg or chick, highlighting the value of nest defense. These findings offer insight into the trade-offs of nest defense in larger predatory birds.