Bird Sudoku Level 139 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 139 Strategy
Hard Level 139 uses a 9x9 board with 29 perch cells, 11 blockers, and 8 habitats. Use the row and column counts first, then test each open diagonal flight line.
Bird Sudoku Level 139 Solution
Bird positions in the solution: R1C3, R1C7, R1C9, R2C1, R3C3, R4C1, R6C1, R6C6, R6C8, R7C1, R9C2.