Loose sticks are piled together, and leaf litter and grass stems are placed to soften the center. Nests are usually placed on horizontal, forked tree branches and can reach up to 30 cm in diameter. Males and females both share in the building of nests by collecting twigs and mouthfuls of leaves and dropping them into position. The breeding season lasts from August to December, but populations in arid areas may breed in response to heavy rains. The male carries out grooming by gently stroking through the plumage of the female with his beak in sessions that can last for 10 minutes or more. During the breeding season, pairs roost closely together on the same branch, often with their bodies touching. Tawny frogmouths are monogamous and mate for life. At night, these birds emit a deep and continuous 'oom-oom-oom' grunting and a soft, breathy 'whoo-whoo-whoo' call.

When disturbed during rest, frogmouths can emit a soft warning buzz that sounds similar to a bee, and when threatened, they can make a loud hissing noise and produce clacking sounds with their beaks. Nestlings make a number of unique calls expressing distress, hunger, and fear. Tawny frogmouths have a wide range of vocalizations they generally use low-frequency sounds to communicate, though some of their warning screams can be heard for miles. When threatened, adults make an alarm call that signals to chicks to remain silent and immobile, ensuring that the natural camouflage provided by the plumage is not broken. Often, a pair sits together and points their heads upwards, only breaking cover if approached closely to take flight or warn off predators. Their plumage allows them to freeze into the form of a broken tree branch and become practically invisible in broad daylight. Due to a cryptic plumage, Tawny frogmouths can be well camouflaged as part of the tree when they perch low on tree branches during the day. Foraging flights consist of short, snatching flights to foliage, branches, or into the air. Some smaller prey, such as moths, can be caught in flight. Tawny frogmouths feed mainly by pouncing from a tree or other elevated perch to take large insects or small vertebrates from the ground using their beaks with great precision. As dusk approaches, they begin actively searching for food.

During the day, they generally perch in the tree and do not actively look for food, though they may sit with their mouths open, snapping them shut when an insect enters.

Do tawny owls hibernate