"The official listing of an animal as endangered can promote poaching, says Max Abensperg-Traun of the Austrian Ministry of Agriculture and Forestry, Environment and Water Management, author of a study on this topic that was published in the May 2009 issue of Biological Conservation. It is a matter of psychology and economics. Perceived rareness makes animals more appealing to collectors and the increasingly limited supply pushes their price up on the black market, making illegal trapping and hunting more lucrative. Wildlife that once existed under the radar suffers from sudden visibility and faddish appeal. In an ironic coup de grâce, endangered species designation can sometimes escalate poaching to the point that it wipes out the species it was intended to protect."
"Endangering Species: Listing Can Make Animals Valuable Black Market Commodities"
Source: Scientific American, 09/09/2009