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
Hip replacement heat-treated alloys and a lack of special surgical experience accounting for most of the failures. In 2010, surgeons at medical centers such as the Mayo Clinic reported reducing their use of metal-on-metal implants by 80 percent over the previous year in favor of those made from other materials, like combinations of metal and plastic. The cause of these failures remain controversial, and may include both design factors, technique factors, and factors related to patient immune responses (allergy type reactions). In the United Kingdom the Medicines and Healthcare Products Regulatory Agency commenced an annual monitoring regime for metal-on-metal hip replacement patients