Logic Masters Deutschland e.V.

THE RULES:

Ordinary sudoku rules apply: place the digits 1 through 9 in each row, column, and 3x3 bold outlined box.

Ornithologically adjacent rule: Some orthogonally adjacent cells are separated by birds. Each such pair of orthogonally adjacent cells contain a pair of ornithologically related digits.

Each variety of bird designates an ornithological relation between a particular pair of orthogonally adjacent digits. For example, all pigeons might separate all the 1/2 pairs, and all peacocks might separate all the 2/3 pairs. This is only a hypothetical example. As you can see, there are no pigeons or peacocks in the grid.

Everywhere in the grid any particular pair of ornithologically related digits appear in orthogonally adjacent cells they are separated by their particular bird. That is to say, all birds are given.

Sven Neumann’s Sudokupad