For the first time since 2004, the Lincoln Park Zoo has two infant gorillas in the same troop, one born on October 11, 2012, and one born on November 16, 2012. The last time the zoo experienced such a special situation was when Susie and Azizi were born more than eight years ago. They still reside at the zoo. Western lowland gorillas are critically endangered in their native central Africa due to an increase in poaching and habitat loss. The gorilla family can be seen daily at the zoo's state-of-the-art Regenstein Center for African Apes from 10 a.m. to 4:30 p.m. Lincoln Park Zoo’s great apes program is considered to be one of the best in the world. The Regenstein Center is internationally known for its enriching exhibit design, and scientists at the zoo’s Lester E. Fisher Center for the Study and Conservation of Apes are described as the best when it comes to disease monitoring and research in behavioral studies. Lincoln Park Zoo, the country's oldest public zoo with an estimated annual attendance of 3 million, is open 365 days a year and admission is free.