Complex sentence: In the 1980s there were as many as 80 million white-rumped vultures ("Gyps bengalensis") in India, when it was the most numerous species of raptor in the world.
Split into simpler sentences: In the 1980s there were as many as 80 million white-rumped vultures ("Gyps bengalensis") in India. At that time, it was the most numerous species of raptor in the world.