Bird Sudoku Level 173 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 173 Strategy
Hard Level 173 uses a 9x9 board with 29 perch cells, 10 blockers, and 8 habitats. Use the row and column counts first, then test each open diagonal flight line.
Bird Sudoku Level 173 Solution
Bird positions in the solution: R1C1, R2C1, R2C4, R3C9, R4C1, R4C5, R4C7, R4C9, R5C1, R6C1, R7C1.