Complex sentence: The herons are a highly mobile family, with most species being at least partially migratory.life species are partially migratory, for example the Grey Heron, which is mostly sedentary in Britain but mostly migratory in Scandinavia.
Split into simpler sentences: The herons are a highly mobile family, with most species being at least partially migratory. Some species are partially migratory, for example the Grey Heron, which is mostly sedentary in Britain but mostly migratory in Scandinavia.