"Terror Bird" is the name given to a variety of large flightless predatory birds found in South America some 62 million years ago in the Cenozoic Era. On Skull Island, the term is used to describe several species of large flight less birds, most of whom are carnivorous, and all of which among some of the largest flightless birds known to exist.
Normal animal motivations.
Lowlands-dwelling Terror Birds are pursuit predators, chasing down small mammals, young dinosaurs, and large invertebrates. Jungle-dwellers tend to eat fruit, insects, and forest-floor centipedes. All of Skull Island's Terror Birds are powerfully built animals, capable of delivering nasty kicks with their clawed feet, while the lowlands species possess huge ax-like beaks.
The Terror Bird character sheets were derived from the Ostrich character sheet found in the 4th Edition HERO Bestiary. I modified the character sheet to account for the 5th Edition method for writing up animals, and then modified each one further to account for the differences in size for each Terror Bird. None of the Terror Birds appeared in King Kong.
The typical Skull Island Terror Bird looks roughly like an Ostrich, with a heavily built body, hairy feathers, bare legs, and long necks. Carnivorous Terror Birds will have thick, muscular necks, while the insect and fruit eaters will have more sinuous necks.
A nocturnal predator of ground-dwelling centipedes, Noctupervagus stands around five to six feet at the shoulder, making it around seven feet tall in total. Weighing roughly 200 kg, Noctupervagus appears as a massively built emu or cassowary, with dark reddish-brown plumage. Noctupervagus lay their eggs on the forest floor, amid the roots of trees, where they are quickly covered with a layer of small plants and mosses. This serves to hide the eggs, although it does make it difficult for chicks to hatch—in many cases the mother will assist in breaking the shell open.