Complex sentence: The species has been introduced to New Zealand, with several hundred birds being released there from 1862 to 1874, though today their range is very localised; the species is now regarded as an invasive pest and the subject of active control.
Split into simpler sentences: The species has been introduced to New Zealand, with several hundred birds being released there from 1862 to 1874. Although their range is very localised, the species is now regarded as an invasive pest and is the subject of active control.