Bird Sudoku Level 172 Hint
Pick a row, column, or habitat with a low remaining count, then check which of its perch cells are blocked by open diagonal flight lines.
Bird Sudoku Level 172 Strategy
Hard Level 172 uses a 9x9 board with 29 perch cells, 9 blockers, and 7 habitats. Use the row and column counts first, then test each open diagonal flight line.
Bird Sudoku Level 172 Solution
Bird positions in the solution: R1C1, R2C4, R2C5, R2C9, R3C2, R3C7, R5C9, R7C1, R8C1, R9C6, R9C9.