The Crossbill Guides Foundation is basically a grass-root organisation of ecologists. Its core consists of Dutch biologists, who founded the organisation from the notion that it is unacceptable that there is only limited in-depth information on Europe’s natural areas aimed at a wide audience.

If we want to increase public involvement with nature conservation, we need to invite people to see through the eyes of nature conservation. 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.

Author / co-author: Biebrza marshes, Coto Doñana, Bialowieza primeval forest (2005), Extremadura (2006, 2011, 2013, 2019), Camargue (2006), Andalusian Sierras (2007), Hortobagy (2008), Cevenes and Grands Causes (2009, 2015), Finnish Lapland (2010, 2017), Loire, Spanish Pyrenees (2011, 2016), Northeast Poland, Eastern Rhodopes (2013), Lanzarote and Fuerteventura, Iceland (2014, 2017), Tenerife and La Gomera (2015), Western Andalucia, Eastern Andalucia, Veluwe (2017, 2018), Southern Portugal (2018), Madeira, Wadden (2019), Provence and Camargue (2020)


Merijn van Leeuwen

Nature is the red thread in Merijn’s life: being a member of the Dutch Youth association for Natural History (NJN) from 12 years on, birds were his first group of interest. This developed into a broad interest in nature and extensive field experience with mammals, herpetofauna, dragonflies, butterflies and recently grasshoppers. He holds a MSc in Tropical and Conservation Ecology at the Free University of Amsterdam (VU). His career lead Merijn to a multitude of places across the globe. He worked in climate change research in the Swedish Arctic, managed the Amsterdam Diemerpark and worked on nature policy for the Province of Flevoland. He developed and lead nature tours for SNP, Natura Aragon and Explorer’s Inn and for Wetlands International he worked on integrating conservation into water management, disaster risk reduction and agriculture in various countries in South-east Asia and Africa. Currently Merijn coordinates the conservation effort for the Amazon and the Atlantic Forest for WWF Netherlands. He thinks ‘selling’ the beauty and importance of nature to the public is a critical part of conservation and this makes him very much at home at the Crossbill Guides Foundation. Privately, he uses Crossbill guides whenever he plans for a holiday.

Neil McIntosh

Neil hails originally from Scotland and moved to the Netherlands in 2005. A graduate of Edinburgh University, he has worked in various sectors including health, education, social regeneration and nature protection. Neil’s last job in the UK was with Scottish Natural Heritage: his work focused on building nature professionals’ capacities in projects and diverse, multi-sectoral partnerships throughout Scotland. Neil has continued to work in equivalent areas at European level. For the last 14+ years, he has worked with various European network organisations, focusing on practical nature conservation, sharing information and experience, to build new know-how: more recently, his work has included development of sustainable tourism initiatives in Europe’s protected areas. Travelling frequently across Europe (and more widely), Neil is able to meet and work together with amazing people and a wide range of organisations. He met Dirk and got to learn about the Crossbill Guides in year one of his move to Arnhem. The deep connections that exist between nature and society have always been special for Neil: on both personal and professionals levels, the relationships between folk and place matter.

Merijn Biemans

Merijn grew up in the south of the Netherlands (Noord-Brabant) and has ever since he was young felt how important it is to safeguard a place for other organisms inhabiting this planet. He holds a MSc degree in Forest and Nature Conservation (Wageningen) with a special interest in ecological networks, philosophy and (organic) agriculture (Minor degree obtained at the University of Copenhagen). He has worked for the European Centre for Nature Conservation and Eurosite, through which he has developed an international network. Furthermore he has worked for the Dutch Natuurmonumenten for 10 years in a variety of jobs. He has coordinated multi-stakeholder projects, has a wide ecological knowledge base (of e.g. Natura 2000) and is smart at the policy-practice interface. As a Public Affairs Manager he has broad experience with effective lobbying, he practiced the MGA method and knows how to achieve goals for better nature conservation and management. In the beginning of 2020 Merijn switched to Waterschap Rivierenland to take up the Program Management of Climate Adaptation Strategies. Merijn is an enthusiastic nature conservationist who always aims to enthuse others for the beautiful, wonderful world that surrounds us and on which we depend so much. Crossbill Guides is such a positive idea Merijn is proud to be part of and hopes to make many more guidebooks happening!

Authors, Illustrators, Designers & Marketing

Albert Vliegenthart

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.

Author / co-author: Eastern Rhodopes (2013), Eastern Andalucia (2017), Wadden (2019).
Redaction (insects): from Hortobagy (2008) until the present

John Cantelo

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.
Author / co-author: Andalusian Sierras (2007), Western Andalucia (2017).
Editing: from Andalusian Sierras (2006) until the present.

Graham Chisholm

Graham has been dedicated to the conservation movement for more than 20 years in the United States. Through his work in leadership positions at The Nature Conservancy and Audubon he has help put over 150,000 hectares into permanent conservation working with private landowners, Native American tribes and public agencies. He is currently a Senior Policy Advisor for the Conservation Strategy Group working increase the conservation impact of infrastructure mitigation in California and climate policy.
As a child he lived in Italy and has maintained a close connection to Italy and the Mediterranean. After many years in the U.S., he returned to Germany to complete dissertation research on the West German Green Party using his time off to further explore Europe’s natural areas. In addition to working with The Nature Conservancy and Audubon in California and Nevada, he has been involved in helping build connections among conservationists working in Mediterranean habitats in California, Chile and Baja California, Mexico.
In the past several years he has started spending more time back in Italy and can’t think of a better way to learn about a new landscape than teaming up with the Crossbill Foundation and colleagues to encourage nature tourism to Tuscany. He looks forward to getting involved in conservation projects and learning from the work in the European Union. He is passionate about supporting the next generation of conservation leaders and ensuring that nature has a strong constituency in the coming century.

Martin Pitt

Martin has had an interest in wildlife since an early age. Although he worked until recently in development and consultancy across the globe, he has always kept this interest alight. He has travelled widely and is keen to explore the ‘sense of place’ that make each location special in the interaction between topography, human culture and the flora and fauna. He is an active member of conservation organisations and currently sits on the Hampshire Ornithological Societies (HOS) Rarities committee.
Primarily interested in birds and mammals, his time living in the Middle East gave him a deep interest in desert ecosystems and the migrant species of the African flyways. Recently he has expanded his interests to butterflies and dragonflies and is currently trying to get to grips with reptiles and amphibians.
Since taking semi-retirement, he also acts a tour guide for Naturetrek, probably the world’s largest eco-tour company and has led a range of tours over the last 4 years including Ethiopia, Morocco, Ethiopia, Extremadura (Spain), Austria, Hungary, Romania and Poland.
For Crossbill Guides, Martin writes the Crossbill Guide to Southern Morocco (planned 2021)

Constant Swinkels

Constant recently graduated as an ecologist and is now a young researcher and lecturer at Radboud University Nijmegen, the Netherlands. Constant has been fascinated by nature from a young age. Whereas his research mainly focuses on the interaction between insects (particularly bees) and vegetation, his natural interests are much broader, covering birds, mammals, reptiles and other insect groups. Having parents who own a book shop and an uncle who writes nature guides, it is no surprise that Constant developed an interest in writing himself, especially the kind of accessible scientific writing that is the benchmark of the Crossbill Guides. For Constant, it is combining the scientific and popular approaches to ecology that excites, whether in his writing, his guiding, in the courses in field biology he teaches, or in his travels around Europe. This is exactly what he does in the Crossbill Guides team, and does so with great enthusiasm. Eventually being able to transfer his new knowledge via the books to a broad readership is the cherry on top!
Primarily interested in birds and mammals, his time living in the Middle East gave him a deep interest in desert ecosystems and the migrant species of the African flyways. Recently he has expanded his interests to butterflies and dragonflies and is currently trying to get to grips with reptiles and amphibians.
Since taking semi-retirement, he also acts a tour guide for Naturetrek, probably the world’s largest eco-tour company and has led a range of tours over the last 4 years including Ethiopia, Morocco, Ethiopia, Extremadura (Spain), Austria, Hungary, Romania and Poland.
Author / co-author: Provence and Camargue (2020), Crossbill Guide route app Veluwe (2017, in Dutch), Crossbill Guide route app Wadden (2019, in Dutch).

Kees Woutersen

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.

Author / co-author: Spanish Pyrenees (2011, 2016), Lanzarote and Fuerteventura (2013), Tenerife and La Gomera (2015), Eastern Andalucia (2017), Southern Portugal (2018), Madeira (2019).

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.

Carsten Krieger

Carsten is a photographer, author and naturalist based in the west of Ireland. He was born in southern Germany but a holiday trip to Ireland got him hooked on the ‘Emerald Isle’ and he moved there permanently in 2002. The move brought a career change from paediatric nurse to freelance photographer and rekindled his childhood fascination with nature.

Since he settled in Ireland he has photographed and written more than ten books on Ireland’s landscape, nature and heritage and has been working on numerous assignments in the tourism sector.

In 2018 Carsten decided to concentrate exclusively on natural history photography, writing and conservation work. Since then he has been invited to be an AnTaisce Climate Ambassador and a Biodiversity Ambassador for Greensod Ireland. He has been working with Ireland’s major NGOs  and is a project manager for Loop Head Together for Nature, a grassroots group that focusses on protecting and improving natural habitats on the Loop Head Peninsula in County Clare (

Carsten is the author of the Crossbill Ireland Guide.

Kim Lotterman

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.

Redaction: from the first guide (2005) until the present

Bouke ten Cate

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.
Author / co-author: Northeast Poland (2013), Eastern Andalucia (2017).

Frank Jouandoudet

Frank  was born near Bordeaux (France) in 1965. He has been a ‘nature addict since childhood’ as he puts it. His first job was in a natural reserve in Arcachon bay near Bordeaux. Frank currently divides his time working as a teacher of classical languages, and studying the natural world of the French region of Aquitaine and Dordogne. Frank published several books on orchids (e.gGuide des orchidées communes de France; 2011, and À la découverte des orchidées sauvages d’Aquitaine; 2004 and 2015), but he really is an all-round naturalist. Besides books on orchids, Frank wrote books on the Archochon nature reserve and its tributary river, the Eyre. Additionally, he is a keen nature photographer.
For Crossbill Guides, Frank co-authored the Crossbill Guide to Dordogne (2018).

David Simpson

David has been passionate about wildlife since he was a child, firstly watching butterflies near his home and later birdwatching. He studied Geography at Sheffield University and volunteered for the RSPB at their Ouse Washes and Coombes Valley reserves. Soon afterwards he began a twenty-year reserve wardening career in northern England, first on the Farne Islands and subsequently in Ravenglass and finally the Sefton Coast. A childhood dream of working in the tropics took him to the Seychelles in 2001 where he volunteered with his partner Audrey for the Nature Protection Trust of Seychelles and later to Mauritius where they were island wardens for the Mauritian Wildlife Foundation at Ile aux Aigrettes. They moved to France in 2002 and now live and work in the Dordogne near Bergerac where David is a wildlife guide.
David has published several articles in British Wildlife on Black-headed Gulls, Natterjack Toads and the Dordogne. In 2010 he wrote the book Birding Dordogne in the popular BirdGuides series and is the Dordogne contact for the European Butterfly Group, part of Butterfly Conservation UK. He has contributed over twenty monographs to the Aquitaine Butterfly Atlas and was a committee member for the Red Data List report of butterflies in Aquitaine.
For Crossbill Guides, David wrote the Dordogne Crossbill Guide (2018)

Alex Tabak

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.
Author / co-author: Eastern Rhodopes (2013), Lesbos (2016).

Chris Braat

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.

Horst Wolter

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.

Oscar Lourens

Graphic Designer
Partner in crime, man of few words.