The Crossbill Guides Foundation is basically a grass-root organisation of ecologists. Its core consists of young Dutch biologists, who founded the organisation from the notion that it is unacceptable that there is only limited information available for non-scientists on Europe's most important natural areas. If we want to maintain, let alone increase public involvement with nature conservation, the first thing that needs to be done is to invite people to see through the eyes of an ecologist  and nature conservationist. We created a concept in which we think this target is best met: The Crossbill Guides.


Dirk Hilbers Director and Author
Dirk Hilbers is the founder and director of the Crossbill Guides Foundation and the principal author of the Crossbill nature travel guidebooks. Dirk has been interested in nature since childhood and has been active in the NJN, the Dutch youth organisation for field biology, for many years. During his studies in ecology at the University of Nijmegen, Dirk found out he wanted to focus on nature conservation. The biggest challenge in this was to bridge the gap between conservation and the general public. The conspicuous lack of information on the value of Europe's most important natural areas (Natura 2000) was a special incentive to start the Crossbill Guides Foundation. He found himself a great job: combining nature trips and reliving them when writing the travel guides. Next to his part-time job at Crossbill Guides, Dirk also teaches topics such as Science & Society and bioethics at the University of Amsterdam.

Board of Directors

Johanna Winkelman Chair
Johanna Winkelman has been active as a chairman of the Board of Directors for the Crossbill Guides Foundation since the start of 2014. She was familiar with the guidebooks before she became part of the board, since she used them during her own travels. Johanna studied biology at the Free University (VU) in Amsterdam and the University of Wageningen focusing on ecology, animal systematics and nature conservation in the (sub)tropics. She also decided to take another study in scientific journalism at University of Applied Science Utrecht. Johanna was awarded with many distinctions during her professional career at organisations such as the Netherlands Society for the Protection of Birds, Birdlife International, Alterra Research Institute – Wageningen University, and many more. Johanna’s main motivation and challenge is to take Crossbill Guides to another level. Increasing quality and publishing new books will create more awareness, which in turn will increase awareness for conservation of our beautiful European nature.

Theo Verstrael Secretary of the board
Theo Verstrael has been part of the Crossbill Guides Foundation since 2011. He was asked to take part in the organisation as a board member during his time as Director of Vlinderstichting (foundation for butterflies). Theo studied biology at the State University of Leiden and became a specialist in ecology and environment biology. He started his career at the Dutch Bureau of Statistics and worked together with SOVON (bird research) for many years. After nine years of being the principal at Vlinderstichting, Theo decided to switch to bird research and became Director of SOVON. Theo finds the Crossbill Guides very fascinating to work for, especially because knowledge and the love for nature are linked to specific natural areas. The guides add value to the flora, fauna and the landscape described.

Dennis Wansink Board member
Dennis has been part of the Board of Directors since 2012, and has found the work a great challenge. The Crossbill Guides Foundation was evolving fast, becoming more professional and expanding its possibilities. Dennis has worked in (voluntary) jobs at nature clubs since he was 15 years old. Later on he worked for the Department of Agriculture, Nature and Food and the Department of Waterways and Public Works, the University of Utrecht, the Foundation for mammals and many more. Dennis is also active for The Foundation for Habitats to help voluntary workers and nature researchers and protectors from overseas. Dennis wants to support the Crossbill Guides Foundation with his knowledge and experience, in order to help people  better appreciate and enjoy the beauty of nature. Nature and all its aspects will always keep surprising you.

Mart Wolter Board member


Albert Vliegenthart Author
Albert Vliegenthart is one of the authors of the Crossbill nature travel guidebooks, and also assists Dirk in acquisition. He has been interested in nature since his childhood, when he was a keen member of the NJN (Dutch youth organization for field biology). After studying plant biotechnology in Delft, he started working as a molecular biologist in a private company where research in crop characteristics was only sometimes combined with nature aspects. Meanwhile his passion was kept alive by travelling throughout Europe, exploring nature from North to South. Albert’s favourite destination is definitely Greece. It may be no surprise that a Crossbill Guide will be an outcome of this enthusiasm. Albert also guides butterfly-tours for the Dutch nature travel company SNP (formerly provided by EcoTourist Services), where his knowledge of butterflies, dragonflies, birds and other ecological topics can be shared with ecotourists. Since 2007, Albert has worked at the Dutch Butterfly Conservation (De Vlinderstichting) as a project leader. Albert enjoys the variety of this work, which includes protection and habitat management for butterflies and dragonflies. 

Kim Lotterman Author
Kim Lotterman has been the principal ecological editor of the guidebooks since the start of the Foundation. Together with local experts, he thoroughly checks the ecological correctness of the content of each book . His credo is 'if I get out of it what I want and my mother still finds it an enjoyable read, it's good'. Kim also writes short sections of the guidebooks, and does additional ecological research, being the main ecological consultant for the author, Dirk. He also gets to do the thankless jobs like constructing the long, multi-lingual species lists at the back of the books. In daily life, Kim works as a researcher at an ecological nature research and consultancy group called 'Natuurbalans', where he focuses mainly on flora. Before working there, he studied biology and environmental studies at the University of Nijmegen. In his spare time, Kim enjoys nature, having a broad ecological interest ranging from mosses and lichens to butterflies and birds, but his main interest lies in the flora of the Netherlands and the rest of Europe. Nature conservation starts with knowledge about natural areas, their ecology and the factors influencing them. Kim values the Crossbill Guides a lot because they inform tourists and local people about these topics. You can enjoy nature so much more when you know why certain things happen, or why particular species live in an area.

John Cantelo Author
John Cantelo assists by editing the English, and the ornithological and historical content of the Crossbill Guides. John has been interested in wildlife since early childhood and first became involved in promoting the understanding of wildlife whilst at school in Southampton (UK). Having gained a degree in History and Sociology (Keele University), he pursued a career in teaching both subjects at secondary level. After moving to part-time school teaching, he combined this with working as a field teacher for the RSPB (Royal Society for the Protection of Birds) until his retirement. He has been an active member of the Kent Ornithological Society (KOS) serving on their executive committee and as their newsletter editor. He is also an active member of the Andalucia Bird Society having written a number of articles for their magazine and more recently by acting as assistant editor. As well as watching them, he is also interested in drawing and painting birds. History continues to run a close second to wildlife in his interests. In recent years, he has spent much time in Andalucia where he has a second home.

Bouke ten Cate Author
Bouke ten Cate has been an avid nature enthusiast since childhood. He had been enjoying the foundation's guidebooks for years before he became part of the Crossbill Guides team of authors in 2011. Bouke studied Forestry and Nature Management at Van Hall Larenstein University of Applied Sciences in Velp, the Netherlands and has been doing volunteer work for several Dutch NGO's such as BirdLife Netherlands, SOVON and RAVON. His fascination with nature began with birds but has spread to the fields of orchids, mammals, reptiles and amphibians. Apart from being a nature enthusiast he also greatly enjoys nature photography, which comes in very handy when working on a guidebook. Instead of merely directing the reader to the region's rarities, Bouke likes the fact that the guidebooks really explain what’s going on in nature, by showing how environment, climate, flora, fauna and human activity interact. They show the unique circumstances that make the described region so special. This deeper understanding of nature really heightens the visitor's appreciation of the experience. His motto is 'see everything that is to be seen' so exploring Europe's most wonderful natural areas on behalf of the Foundation was something of a dream come true for him.

Kees Woutersen Author
Kees has been one of the authors of Crossbill Guides since 2008. From the moment he set eyes on a Crossbill Guide for the first time, with its wide range of nature topics and practical information, he knew that this was what a nature traveller abroad needs to get around. Kees worked as a teacher in economics and as a consultant for small businesses. He was also a member of a Dutch youth organisation for field biology (CJN) and several bird groups, for many years. Once established at Huesca, in the foothills of the Spanish Pyrenees, he worked professionally with birds and nature. He started his own travel company, organising nature tours and bird trips all over Spain and publishing several books, e.g. Atlas of the Birds of Huesca (1998). Besides, Kees is active in local bird and nature organisations, organising and working on education. Kees thinks these books, thorough as well as accessible to the general public, play a big part in publicising the most important natural areas of Europe. He thinks Crossbill Guide activities can convince administrations at different levels to put nature conservation higher up their agendas.

Alex Tabak Author
Alex has been active for Crossbill Guides since 2011. He was familiar with the guidebooks from bookshops. As an author and illustrator, Alex found the guides an amazing tool to combine his love for nature, with discovering the most beautiful parts of Europe and in turn sharing thiswidely. Alex studied Biology at the University of Wageningen and specialised in field surveys of flora, vegetation, reptiles, amphibians and butterflies. He is currently working as a freelance ecologist, and in the past was an ecological advisor for has worked for the management consultant company Arcadis, and the Dutch Government as an ecological consultant. He was active within the field of vegetation sampling, plant identification, protected animal surveys and habitat mapping, which makes him a great asset to the team. Next to biology, Alex has a passion for music, and he plays electric guitar in rock bands. For many years he played in a succesful surf rock and rockabilly band and did many gigs around The Netherlands, also in famous venues such as Melkweg and Paradiso. "Growing old is compulsory, growing up is optional". This saying has translated into his enthusiasm and creativity for writing the Crossbill Guides. Alex wants to inspire others to enjoy nature and every bit of life by sharing this enthusiasm for the natural world.

Illustrations & Graphic Design

Horst Wolter Illustrator
Horst Wolter (1977) has been drawing ever since he was able to hold a pencil. When Dirk asked him to make a schematic overview of the habitats of the Biebrza river for the first Crossbill Guides publication, he immediately agreed. Horst is now the illustrator of the Crossbill Guides Foundation. After finishing high school, Horst had the choice to either study biology or to go to art school. He chose biology at the University of Nijmegen, where he received his master's degree in 2002. All through his studies Horst kept on creating illustrations of the various aspects of nature, from wild flowers and animals to the intricate patterns of organs and cells. His main fascination lies in the complex shapes and structures you can find everywhere in nature, and how these all have a purpose or function within 'the bigger scheme of things'. Examining and drawing these often cunning structures (from cell to ecosystem) gives a great insight into 'the why of things'. Within his work for Crossbill Guides Horst brings together his love for nature, fascination for its workings and his skills as an illustrator.

Chris Braat Illustrator
Chris has been active as an illustrator for the Crossbill Guides since 2006. The first book he worked on was Extremadura 1st edition, and he has worked on many others. Chris makes the overview illustrations inside the front covers, and the illustrations of species in region maps. Since he was only 10 years old, Chris has been interested in nature and was often to be found in the dunes of Haarlem. He started his study in Biology at Wageningen University, after which he worked for the NGO Natuurmonumenten for many years. In 2008 he became director of the Free Nature Foundation, which manages areas where nature remains largely undisturbed, only influenced by the weather and wild animals. Cattle and horses are often used in the management of these areas. Since 2012, Chris is manager for NAtuurmonumenten of the National Park Schiermonnikoog.
 For Chris, the Crossbill Guides are more than just travel guides. Apart from their quality and usefulness for different kinds of people (experts and hobby travellers), the Crossbill Guides can really contribute to an area’s economy. The guides help tourists to go to specific areas, which boosts local initiatives.

Oscar Lourens Graphic Designer

Sam Gobin Graphic Designer
Sam has been working for the Crossbill Guides Foundation as a graphic designer since 2011. It was a way to make a dream come true to develop and improve a concept and contribute to the protection of nature. The Crossbill travel guides make it possible to enjoy, explore and share all the beauty offered by European nature. In the past, Sam studied biology, but changed direction to Biomedical Research. A couple of years later, Sam decided to do something more creative and went to the Art Academy in The Hague, where he graduated as a Graphic Designer. He is currently managing his own business, running different projects for non-profit nature conservation and scientific organisations and charitable foundations. Sam believes his work for the Crossbill Guides Foundation is a way to give back something. He enjoys being part of the organization and help to create something even better. Nature is even closer than you might think, and with these guidebooks everyone is able to explore Europe in a different way.

Marketing & PR

Marjolein de Graaf Marketing & PR
Marjolein joined our team in 2017 to manage and facilitate the PR and network building for the Crossbill Routes App and guidebook of De Veluwe, Netherlands.
Marjolein is a passionate rambler and enjoys the ‘good country life’ – the local food and the fine landscape of the region. 
Marjolein is a great network builder and organisor.