His father Paul Franz Constantin Grzimek was a lawyer and civil law notary and his mother was Margarete Margot (nee Wanke).

In early 1945, the Gestapo raided Grzimek's Berlin apartment, because he had repeatedly supplied food to hidden Jews.

He was then reinstated at the Zoo by the U.S. government but his reputation was compromised as there was a NSDAP entry as a candidate but not as a member; following a 1949 lawsuit Grzimek was given a fine.

With festivals, dances and actors, Grzimek attracted the Frankfurt population, while receiving the assent of the Provisional Government and the U.S. military to continue the Zoo.

The society – organized on similar principles as its London and New York counterparts – runs a number of wildlife conservation projects both in Germany and overseas; most well-known is its ongoing work in the Serengeti ecosystem in Tanzania, East Africa.

He spent several years studying its wildlife there alongside his son Michael, especially on observation and counts of large scale annual migrations.

In the coming decades and centuries, men will not travel to view marvels of engineering, but they will leave the dusty towns in order to behold the last places on earth where God’s creatures are peacefully living.

Palaces can be rebuilt if they are destroyed in wartime, but once the wild animals of the Serengeti are exterminated no power on earth can bring them back.In 1975 he co-founded the League for the Environment and Nature Conservation (BUND) and bought ten acres of forest and wetlands in the Steiger forest near Michelau im Steigerwald which he left wild.

All the versions of the encyclopedia are marked by clear and forceful prose, extensive use of illustrations (both drawings and color plates), and a deep love and concern for animal conservation.

He also authored a large number of popular books based on his countless experiences with animals which he raised since his student days, managed as zoo director, and encountered in the wild during many research trips.