Koester along with Heinrich von Zügel was one of the most important Impressionist animal painters from the Munich School. Originally pressured by his family to become a pharmacist, Koester abandoned his studies and entered the Staatliche Kunsthalle in Karlsruhe. There he trained under some of the more established painters in Germany such as Carl Hoff, Claus Meyer, Heinrich Von Zügel, and Leopold von Kalckreuth.

Koester's main residence was in Munich, but he spent most of his time painting in Klausen in the Tirol. His early pictures were genre scenes of Tyrolian folk life and landscapes, later specializing in painting ducks, which would establish his reputation.

Koester attracted attention the moment he firs...