A dwarf swan meanders by as zookeeper Yancy Rentz (L) and biologist Benjamin Ibler count ducks in a bird enclosure during the annual animal inventory at Zoo Berlin zoo on December 12, 2012 in Berlin, Germany. The zoo conducts the once-a-year inventory over a period of several months, depending on the species, to assess such factors as the state of animal colonies, the presence of foreign species and the true number of species and their members.