Bird Sudoku Level 257 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 257 Strategy
Master Level 257 uses a 10x10 board with 50 perch cells, 11 blockers, and 11 habitats. Use the row and column counts first, then test each open diagonal flight line.
Bird Sudoku Level 257 Solution
Bird positions in the solution: R1C1, R2C3, R2C10, R3C5, R3C6, R4C9, R5C1, R5C9, R7C4, R8C1, R8C8, R9C1, R10C5, R10C8, R10C9, R10C10.