Bird Sudoku Level 189 Hint
Look for perches that share long open diagonals. If no blocker sits between two possible birds, those placements cannot both be used.
Bird Sudoku Level 189 Strategy
Expert Level 189 uses a 9x9 board with 35 perch cells, 11 blockers, and 9 habitats. Use the row and column counts first, then test each open diagonal flight line.
Bird Sudoku Level 189 Solution
Bird positions in the solution: R1C4, R2C1, R3C1, R3C3, R3C8, R4C8, R6C2, R6C7, R6C8, R7C2, R9C2, R9C3.