There are 4 vivid cast-iron statues near the entrance, featuring hunting scenes. 3/4 show noblemen hunting w/dogs classic German prey: boars, stags, foxes. The fourth features an American buffalo & the statue is dated 1902. Why a buffalo? Was there ever a live buffalo in Tiergarten (hunted or kept in a zoo)?
From Berlin's monuments database ("Die Jagdgruppen und Tierfiguren.."):
The hunting groups and animal figures that Kaiser Wilhelm II had erected in the park illustrate the significance of Tiergarten as the former princely hunting reserve of the Hohenzollern. In 1904 Cuno von Uechtritz-Steinkirch created the imposing fountain of Saint Hubert, which was removed in 1938. The corresponding hunting scenes ("Ancient Germanic Wisent Hunt" by Fritz Schaper, "Boar Hunt around 1500" by Carl Begas, "Hare coursing in 1750" by Max Baumbach, "Fox Hunt around 1900 "by Wilhelm Haverkamp) are today in the Fasanerieallee (5)
In other words, it depicts the hunting of a Wisent, also known as the European Bison, rather than an American Bison.