Red-legged Seriemas live in the dry, open grasslands and scrub habitat of central and eastern Brazil to eastern Bolivia. They can be found as far south as Paraguay, Uruguay, and northern Argentina. They are among the largest ground-dwelling bird in the Neotropics, second only to Rheas. While they are most commonly found in grassy savannas, they can also be found as high as 6500 feet above sea level. They will also visit areas that have recently been burned by fire to gain easy access to prey.

Seriemas spend most of their time walking through grasses and scrublands in pairs or small groups whilst looking for food. They only fly when required to avoid predators or to perch on tree branches. Rather than fly they often lie down if threatened, relying on its neutral colouring to camouflage it.

They are a territorial bird and have a loud call, often performing a duet with a partner. Their vocalizations are a series of loud, high-pitched yelps and will use them regularly to respond to other pairs in nearby territories. Their call can be heard from over a mile away.

Seriemas breed during the rainy season which varies based on the region in which the birds live. The males perform a display that includes extending the wing to show off flight feathers and strutting in front of the female that they are courting. Occasionally, fights between rival males have been observed and primarily involved kicking at one another.

Red-legged Seriemas feed on a variety of small animals including mammals, reptiles, and birds. They are one of the few animals that will kill and eat venomous coral snakes. They kill their prey by slamming it on the ground or a hard surface such as a rock. If their prey is too large to swallow whole, a Seriema will hold its prey in its beak while using its very sharp, sickle-like claw, found on the second toe, to tear it into smaller bites. 

They are one of the few birds to have eye lashes! And have a life expectancy of between 20 and 25 years.