The purple emperor, one of Britain's most spectacular butterflies, requires large areas of mature broadleaf woodland with sallow understorey and is sensitive to intensive woodland management.
Larval purple emperors depend entirely on sallow leaves, and the destruction of sallow through woodland management or deer browsing eliminates entire local populations. Adult butterflies are territorial and require sufficient woodland area to maintain populations. Fragmented woodlands without connectivity prevent dispersal between sites. The welfare of individual butterflies in declining populations is inseparable from the habitat management decisions that determine whether sallow is present.