Dieter Blume (1920-2004) was a biology teacher in Gladenbach, Germany, who in his spare time made monumental contributions to European woodpecker research. Blume did most
of his field work on foot from his home over a period of more than 40 years. He published 18 German-language papers and 3 German-language books on woodpeckers, as well as the
English-language species accounts on woodpeckers in the Handbook of the Birds of Europe, the Middle East, and North Africa: The Birds of the Western Palearctic, Volume 4 (1985).

In this photo Blume is explaining about wood chips under a nest of Grey-headed Woodpecker (Picus canus)

Gladenbach, Germany