The southern hemisphere is not a mirror image of the north.
the crows approached the female banteng, somehow indicating their intention. The banteng female then rolled onto her back and held her legs up, straining to hold her position, so that the crows could get to the belly and the area between belly and leg. The crows then proceeded to quickly peck at the exposed areas, the authors assuming that the crows extracted ticks and the cow then rolled back onto her belly.
Here is a bird exceptionally endowed for song and yet so much of what is produced seems to have no easily identifiable function.