Darwin's Nothura are terrestrial and when disturbed, prefer to escape by running. When flushed, they fly well and fast, however. The flight is low, only 2-5 m above the ground (Wetmore 1926) but flight distances range from 20-400 m, and the flight direction usually is straight or forms a wide arc (Bump and Bump 1969). The members of a pair usually do not flush together, and often fly in divergent directions. Generally, nothuras are not particularly wary, except where they are heavily hunted (Bump and Bump 1969).
Darwin’s Nothura forage and roost on the ground. Roosting sites slight hollows on the ground, marked by an accumulation of droppings. Favored sites for roosts are between two adjacent clumps of bunchgrass or under an overhanging canopy of drooping leaves of grass. A bird may return to the same roosting site for several nights in a row (Bump and Bump 1969).
There are no published data on territorial defense, maintenance, or home range size for Darwin's Nothura.
Copulation may last for at least two minutes, during which the female squats with the head angled uo, and moves the head rather rapidly from side to side in an arc of 90º (Bump and Bump 1969). The male, meanwhile, sometimes struggles to maintain his balance, and stabilizes his position by stretching the wings outwards a little and downwards to touch the body of the female.
Promiscuity and homosexuality was observed by Bump and Bump (1969) in penned birds. When several of each sex are penned together, occasionally a female may copulate with two males within a period of a few hours. One female was observed to mount another. Little seems to be known about sexual behavior of Darwin's Nothura in the wild, but from what is known of the breeding system of other species, "the general rule among tinamous is simultaneous polygyny for males and sequential polyandry for females" (Cabot 1992).
Social and interspecific behavior
Darwin’s Nothura is not gregarious, and usually are solitary or in pairs (Bump and Bump 1969).
Potential avian predators (hawks and owls) and a wide variety of mammalian predators (e.g., foxes, opossums, and skunks) are common in the range of Darwin's Nothura, but Bump and Bump (1969) found few confirmed instances of predation in their field work in Argentina; "some feathers were found fairly frequently but carcasses were seldom located".