Explanation: Species judged as threatened are listed by various agencies as well as by some private organizations. The most cited of these lists is the Red Data Book. It is a loose-leaf volume of information on the status of many kinds of species.

• This volume is continually updated and is issued by the International Union for Conservation of Nature (IUCN) located in Morges, Switzerland.
• “Red” of course is symbolic of danger that the species both plants and animals presently experience throughout the globe.
• The Red Data Book was first issued in 1966 by the IUCN’s Special Survival Commission as a guide for formulation, preservation and management of species listed.
• In this Book, information for endangered mammals and birds are more extensive than for other groups of animals and plants, coverage is also given to less prominent organisms facing extinction.
• The pink pages in this publication include the critically endangered species. As the status of the species changes, new pages are sent to the subscribers.

Source: Shankar IAS Environment book