Current work at CEH Banchory on N deposition and mountain hares (Lepus timidus) suggests that N deposition leads to habitat change with a loss of Racomitrium heath. There is evidence to suggest this can have a negative impact on hare numbers, as an increase in grass species favours sheep over hares. Hare numbers then decline. The exact mechanisms are not known at present, however research is ongoing (van de Wal pers. comm.).