Cougar Mountain Zoo 2009, Peter Rittler continued in the zoo's management. The zoo collection features 32 exhibits of animal habitats concentrating on endangered species such as tigers, lemurs, wolves, reindeer, cranes, wallabies, macaws, and cougars, among others. On June 16, 2007, the zoo acquired two male Bengal tiger cubs, a royal white and a golden, who were born eight weeks apart in a Florida tiger preserve. The zoo added an additional two cubs in 2009. A glass-walled tunnel called the "Tiger Tunnel" enables visitors to view tigers in close proximity. In 2011, a 370-pound (168 km) tiger was photographed holding his paw up
History of Edinburgh Zoo chimpanzees at Edinburgh were found to use word-like vocal labels for food. In late 2005 the Animal Liberation Front (ALF) threatened action over the holding in captivity of Mercedes, then Britain's only polar bear. The zoo had initially planned to retire their polar bear exhibit after Mercedes died. When zoo officials announced plans to create a new attraction, citing their responsibility to ensure the survival of the species, the ALF threatened damage to zoo workers' property and other scare-tactics. Edinburgh's treatment of polar bears had often been subject to criticism, punctuated by incidents like the death in 1997 of Mercedes'