What is the devil quartet?

The devil or ‘evil quartet’ is a sobriquet used to describe the four major causes that have led to the accelerated rate of extinction of species. These causes have been attributed mainly to human activities like extensive deforestation and poaching. These cause habitat loss and fragmentation, over-exploitation, alien species invasion and co-extinction. In the context of music, the word quartet is used to describe a group of four singers or instrumentalists or a musical composition for four voices or instruments.