I practice a form of Roman divination that involves quartering the sky and looking for certain species of birds. To begin, I set up a perimeter using local landmarks. I quarter what I have marked off, then quarter within each quadrant again, forming a matrix of sixteen squares. I set a beginning and ending time to watch for birds entering, exiting or staying within the quadrants.
The six species used for this divination are the eagle, vulture, hawk, goose, woodpecker and crow. The eagle, vulture and hawks are good signs, the goose a warning, the woodpecker a conflict, and the crow a bad sign. The directions of ill omen are north and east, good omen – south and west. An odd numbers of birds is a good sign, while an even number is a bad sign. If no bird appears in the allotted time, it means a neutral event.
Each species of bird has their own methods of appearing. Woodpeckers move up and down trees, therefore I would look for a tree in a quadrant that I marked out. Meanwhile, vultures rarely land and instead circle the sky. Geese move in flocks, while hawks and eagles fly alone. Sometimes, several species will appear together such as crows and vultures. If a crow is exiting a northern quadrant, while a vulture is circling in an eastern one, it is a sign that your luck will be variable that day. Shades of meaning come from species of birds, their movements, their number, and their placement in quadrants.
The setting up of the quadrants sets a beginning probability of a bird appearing in one of the squares. Adding to this, the number and species of bird creates compound probabilities. Then there is the probability of that omen coming true such as sighting a vulture in the south-west quadrant.