After his biology study Chris started working for Dutch Butterfly Conservation helping out on the first atlas of Dutch butterflies. After a two year intermezzo teaching animal ecology at Wageningen University, he returned to Dutch BC in 1990 to start up the Dutch Butterfly Monitoring Scheme, and would stay coordinator for Dutch Butterfly Monitoring until 2026.
During his career he produced three Dutch Red Lists of butterflies, three Red Lists of European butterflies, and one on butterflies of the Mediterranean. After he co-developed the European Grassland Butterfly Index he helped setting up the eBMS, the European platform where all butterfly monitoring data comes together to produce European trends and indicators.
He produced more than 400 papers, around 60 of them peer-reviewed scientific papers, the rest mainly in Dutch. In 2012 he did his PhD on ‘Tracking butterflies for effective conservation’.
He was co-author of the 2006 Dutch Butterfly atlas and is currently working on a new atlas on the butterflies of the Netherlands, which will be published 2027 or 2028. Together with British colleagues Martin Warren and Sam Ellis he is also one of the authors of the “Conservation Atlas of European Butterflies”, which will be published in 2026 or 2027.
In 2004 he was one of the founding fathers of Butterfly Conservation Europe, and was chair of this increasingly influential and timely organization from 2016 to 2019.