He became an associate professor at the University of Wroclaw and later became a head of the department of comparative zoology. He then established an ornithology department and headed it until 1969. In 1963 he organized the EURING, a collaboration of European ornithologists studying bird migration. Rydzewski founded and edited "The Ring" in 1954, publishing it from Croydon for the first six years and then from Wroclaw until his death in 1980. He also served as editor (1962-1973) of "Acta Ornithologica" published by the Polish Academy of Sciences in Warsaw.