The apostle bird also known as the grey jumper, lousy jack or cwa bird is a quick-moving, gray or black bird about 13 inches (33 centimetres) long. It is a native to Australia where it roams woodlands, eating insects and seeds at, or near, ground level. Apostle birds often travel in groups of about 12; for this reason they were named after the Biblical apostles, the twelve chief followers of Jesus Christ.

Measuring around 33 cm (13 in) in length, the apostle bird is a predominantly dark grey bird with a long black tail tinted greenish in sunlight. The grey feathers on the head, neck and breast are brushed with paler grey-white and the wings are brownish. The legs and bill are black and the eyes brown or white.

Apostle birds are a socially living, cooperative breeding species with each breeding group generally containing only one breeding pair, the rest being either their helper offspring, kin or unrelated adult birds. Most group members help construct a mud nest, share in incubation of the eggs, and defence of the nest. Once the eggs are hatched, all members of the group help feed the chicks and keep the nest clean.

Apostle birds are a fission-fusion society. In winter, birds flock in larger groups, and as breeding season approaches winter groups break into smaller breeding groups. This change in group size is a consequence of breeding groups merging in the winter and breaking apart again in the summer breeding season. Breeding groups use small, non overlapping home ranges around the nest site, while winter ranges are larger with groups freely interacting with other groups

Breeding season is from August to December. The nest is a deep cup-shaped structure made of grasses held together with mud or sometimes manure in a tree fork up to seven or eight metres above the ground. Three to five pale blue-white eggs sparsely splotched with brown and lavender shades are laid measuring 22 mm x 29 mm. They are tapered oval in shape