Animals at the Zoo (51 images)

Su Lin, a 2-year-old giant panda at the San Diego Zoo, enjoyed the cool feel of snow on an unusually hot day in San Diego on April 27, 2008. The San Diego Zoo's Giant Panda Research Station was covered in 15 tons of snow on Sunday. In two weeks, on May 10, the Zoo's polar bear exhibit will be blanketed with snow as part of Bear Awareness Days, presented by Mission Federal Credit Union. The fun and educational four-day event discusses bear conservation efforts. (UPI Photo/Ken Bohn/San Diego Zoo)

Five critically endangered Amur tigers were born at the Saint Louis Zoo in St. Louis on April 28, 2008 The five cubs - two males and three females - are with their mother "Kalista" in an off-display indoor maternity den at Big Cat Country and weigh between 4.5 and 7 pounds each. The family group will remain in the maternity den for about three months. This will allow the cubs to grow large enough to handle the obstacles they will face when introduced to their outdoor habitat. The cubs have not yet been named. (UPI Photo/St. Louis Zoo)

A newborn 238 pound female African elephant calf stays close to her mother Umoya (oo-MOY-ah) just hours after her birth at the San Diego Zoo's Wild Animal Park on September 19, 2007 at 12:23 a.m. This is the fourth African elephant calf to be born at the Wild Animal Park since 2003. Another calf is expected by early 2008. (UPI Photo/Tammy Spratt/Zoological Society of San Diego)

A male trumpeter swan swims with his newly hatched cygnet at Lincoln Park Zoo in Chicago on June 1, 2008. Trumpeter swans were hunted to near extinction by 1900 and now, thanks to managed breeding and recovery efforts, these swans are thriving again in many parts of the Midwest. (UPI Photo/Brian Kersey)