Complex sentence: There are now almost 250 black robins but before in 1980 only five Black Robins survived on Little Mangere Island but were saved from extinction by Don Merton and his Wildlife Service team, and by "Old Blue", the last remaining fertile female.
Split into simpler sentences: There are now almost 250 black robins but in 1980 only five Black Robins survived on Little Mangere Island. They were saved from extinction by Don Merton and his Wildlife Service team, and by "Old Blue", the last remaining fertile female.