They are not quite a new species but the beginnings are clear. The Chappell Island tiger snakes lie at the extreme end of the size spectrum. They are the giants reaching almost two metres. They nest on the island for a few months each year. Here the tiger snake have a much bigger problem than others.
Mutton- birds are fairly large so the snakes can only eat the chicks to a certain size.
This means their annual feast is potentially shorter than on Reevesby Island. To maximize this limited annual food supply they have become larger. This strategy has been successful. The island is also crawling with these amazing snakes. There are some interesting little sidelines to island tigers life.