They were once considered part of the same family but it has since been learned they are unrelated to each other. But whatever the taxonomic position of these birds, they are striking and interesting denizens of Australasia. A few also reside in southern New Guinea. It is considered scarce and I've not come across one on two lengthy visits to this huge tropical islands. This sounds to me like the niche filled by the forktails on southeast Asia.
Birds mostly occur in pairs or small family parties.
More specifically, they showed by biochemical methods that the Apostlebirds and the two members of the Grallina were not closely related, and should not be in the same family. This may be taking things a bit too far. They are even more different from drongos and fantails. Whether or not this impacts the placement of Grallina in the monarchs is something I don't know, but it seems wiser to tentatively retain this family for the present. For now, the unique Magpie-Larks of Australasia seem best considered a separate family.