Complex sentence: The white nests are commonly treated with a red pigment, but methods have been developed to determine an adulterated nest natural red cave nest are often only found in limestone caves in bird nest concession island in Thailand.
Split into simpler sentences: The white nests are commonly treated with a red pigment, but methods have been developed to determine an adulterated nest. Natural red cave nests are often only found in limestone caves in bird nest concession island in Thailand.