Bird-bears (Arctavidae) are a family of large heavily built flightless predatory birds descended from Skuas native to Antarctica. They have completely lost their wings and move about on two strong legs. They live in tropical, sub-tropical, temperate and coniferous forests and tundra preying upon herbivorous flightless birds and mammals, which they ambush and then kill with powerful bites of their hatchet-like beak. They are solitary and individuals require large territories, females being larger than males and so have larger territories. When courting females males build a semi-circular structure of rocks, branches, leaves and bones around a recently killed prey animal which he offers to the female. If she is pleased with his offering she will allow him to mate with her. She will then lay a large single egg which she diligently cares for until her offspring reaches maturity.
The species are:
Kabuki-faced Bird-bear. (Arctavis kabukiops) Lives in temperate and mountain forests. Its upper side is red-brown with a pale yellow to white underside while its face is white with three or four symmetrical black spots on either side. Males are 1.6m tall and females are 2m tall.
Lesser Mountain Bird-bear (Orarctavis minor) Lives above the timberline on mountains. Its upper side is dark grey while its underside is light grey with dark grey speckles. Males are 1.2m tall and females are 1.3m tall.
Greater Mountain Bird-bear (Oractavis major) Lives above the timberline on mountains. The front half of its body and all of is back is light grey while the back half of its body and its haunches are dark grey. Males are 1.4m tall and females are 1.6m tall.
Stripe-necked Bird-bear (Melanopteryx vergacollum) Lives in tropical forests. It is black with thin white stripes along its neck and the front of its chest. Males are 1.1m tall and females are 1.4m tall.
Golden-shouldered Bird-bear (Melanopteryx chrysoscapula) Lives in tropical and subtropical forests. It is black with a golden patch over its shoulders and down its sides. Males are 1.2m tall and females are 1.5m tall.
Polar Bird-bear (Avinanuq albopteryx) Lives on tundras and in coniferous forests. It is light brown in summer and white in winter. Males are 2.4m tall and females are 2.7m tall.
Great Shaggy Bird-bear (Australorex hirsutus) Lives in temperate and mountain forests. It has a brown shaggy coat. Males are 3.6m tall and females are 4.6m tall.