Dirk Hilbers (The Netherlands, 1976), biologist, is the founder of the Crossbill Guides Foundation and travels the continent to write Crossbill Guides about the most beautiful natural areas of Europe. He has specialized in flora, birds, ecology and land use. Herman Dierickx (Belgium, 1958) is an author who has specialised in writing articles on environmental issues, nature and nature conservation in Belgium. Next to countless articles in recommended journals in Belgium, he has also published 13 books on nature in Belgium. Alex Tabak (Belgium, 1958) is an ecologist specialised in field surveys of flora, vegetation, reptiles/amphibians and butterflies. He works partly in the Netherlands, and partly in Greece. Albert Vliegenthart (The Netherlands, 1976) works at de Vlinderstichting - the Dutch butterfly conservancy, and is one of the leading Dutch butterfly and dragonfly experts, next to being a keen birdwatcher. He is involved in most Crossbill Guides as the invertebrate expert. Albert also leads butterfly tours in Spain, France, Greece and Turkey.