CAMBRIDGE, ONTARIO
I’ve been studying the vegetation of eastern North America for over 15 years, but my interest in botany started in my childhood explorations of rural southwestern Ontario. My professional journey began with internships at Ontario’s Natural Heritage Information Centre and the Canadian Museum of Nature. I’ve been fortunate over the years to have had the mentorship of some of Canada’s best naturalists.
I do breeding and migratory bird surveys professionally and as a volunteer for the Ontario Breeding Bird Atlas. Much of my avian work has been to establish baseline knowledge for environmental restoration planning and environmental assessments.
I’ve written numerous environmental impact studies, policy conformity statements, and other environmental review documents. I also conduct species at risk reviews, wetland evaluations, significant wildlife habitat assessments, and many other natural environment studies required for permits and approvals.
EXPERTISE
Botanical Inventories and Plant Identification
Multi-season site inventories, rapid inventories, species identification, and long-term vegetation monitoring. Tree identification, inventory, and risk assessment.
Breeding and Migratory Bird Surveys
Breeding bird surveys and migratory bird surveys using standard protocols. Visual and auditory bird identification. Long-term monitoring. Nest inspections.
Wildlife Habitat Assessment and Monitoring
Identification and assessment of significant wildlife habitat using standard criteria and protocols. Long-term habitat monitoring.
Vegetation Community Assessment
Ecological Land Classification (ELC) and vegetation characterization and assessment using other standard methods and criteria. Wetland delineation and assessment.
Species at Risk Surveys
Targeted surveys for plant, animal, lichen, and other Species at Risk using standard protocols. Mitigation and monitoring plans and implementation.
Geospatial Services
Natural features mapping in the field and on desktop. Biological geodatabase management.
CURRICULUM VITAE
Professional Experience
Senior Ecologist, CBCL Limited, Cambridge, Ontario. 2025 to present.
Consulting Ecologist and Naturalist, Freelance, Cambridge, Ontario. 2021 to present.
Senior Ecologist, North-South Environmental Inc., Cambridge, Ontario. 2018 to 2021.
Environmental Scientist, Parsons Inc., London, Ontario. 2015 to 2018.
Field Biologist, Dillon Consulting Limited, Kitchener, Ontario. 2014.
Consulting Ecologist, Freelance, Kitchener, Ontario. 2011 to 2013.
Environmental Monitoring Student, Canadian Museum of Nature, Gatineau, Quebec. 2010.
Natural Heritage Information Technician, Ontario Ministry of Natural Resources, Peterborough, Ontario. 2009.
Education
Master of Science (M.Sc.) in Ecology and Evolutionary Biology, Western University, London, Ontario. 2025.
Bachelor of Environmental Studies, Honors (B.E.S., Hons.) in Planning, University of Waterloo, Waterloo, Ontario. 2011.
Volunteer Activities
Editor in Chief of the Ontario Plant Press, Field Botanists of Ontario. 2023 to present.
Awards Coordinator, Field Botanists of Ontario. 2019 to present.
Lead Atlasser, Ontario Breeding Bird Atlas. 2021 to present.
Workshop and field trip leader, various organizations. 2011 to present.
Publications
Academic Publications
Oldham, M.J., W.D. Van Hemessen, and S.J. Blaney. 2018. Round-fruited St. John’s-wort (Hypericum sphaerocarpum, Hypericaceae) in Canada. The Canadian Field-Naturalist 132(4), 389-393.
Eagles, P.F.J., W.D. Van Hemessen, and M.K. Legault. 2013. Advanced booking behavior of park visitors: Ontario provincial parks. Journal of Hospitality Marketing and Management 22(8), 832-850.
Other Publications
Van Hemessen, W.D. 2023. Putting heads together to master the asters. Blazingstar 24(4), 11-14.
Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 2023 (under review). COSEWIC assessment and update status report on the round-leaved greenbrier (Smilax rotundifolia) in Canada. 52 pp.
Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 2023. COSEWIC assessment and update status report on the willowleaf aster (Symphyotrichum praealtum) in Canada. 59 pp.
Van Hemessen, W.D. 2022. Noteworthy observations of vascular plants at Bickford Oak Woods Provincial Conservation Reserve, 2017-2021. Ontario Plant Press 34(3), 11-15.
Catling, P.K., D.A. Bettencourt, and W.D. Van Hemessen. 2022. Recovery strategy for black ash (Fraxinus nigra) in Ontario. Ontario Ministry of the Environment, Conservation and Parks. vi + 67 pp.
Catling, P.K., D.A. Bettencourt, and W.D. Van Hemessen. 2022. Recovery strategy for Gillman’s goldenrod (Solidago gillmanii) in Ontario. Ontario Ministry of the Environment, Conservation and Parks. x + 28 pp.
Catling, P.K., W.D. Van Hemessen, S. Mainguy, et al. 2022. Survey and monitoring protocol for false hop sedge (Carex lupuliformis). Prepared through the Ontario Species at Risk Stewardship Program. 71 pp.
Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 2021. COSEWIC assessment and status report on the pumpkin ash (Fraxinus profunda) in Canada. 61 pp.
Oldham, M.J., P.W. Deacon, and W.D. Van Hemessen. 2020. The spread of spring avens (Geum vernum) in Ontario. Field Botanists of Ontario Newsletter 32(3-4), 3-5.
Campbell, D., P. Campbell, and W.D. Van Hemessen. 2019. Oval-leaved ladies’-tresses (Spiranthes ovalis var. erostellata) discovered in Elgin County. Field Botanists of Ontario Newsletter 31(3), 8-9.
Van Hemessen, W.D. 2018, January 18. Putting citizen science in action to capture Canada’s “nature selfie”. Guest blogger for the Canadian Wildlife Federation. http://blog.cwf-fcf.org/index.php/en/putting-citizen-science-into-action/.
Van Hemessen, W.D., J. Scott, T. Doucette, and K. Houston. 2016. Road mortality hot spots of turtles: A three-year Ministry of Transportation study in Brant County, Ontario. Resilient Infrastructure: 2016 Canadian Society for Civil Engineering Conference TRA-904-1.
Cray, H.A., M. Drescher, and W.D. Van Hemessen. 2015. Effects of urban development on vegetation communities at the edges of regional woodlands. Regional Municipality of Waterloo, Kitchener, Ontario.
Presentations
Van Hemessen, W.D. 2023, October 25. Asters and their friends. Presented to Lambton Wildlife Inc., Sarnia, Ontario.
Van Hemessen, W.D. 2022, December 5. The orchids of Oxford County. Presented to the Woodstock Field Naturalists, Woodstock, Ontario.
Van Hemessen, W.D. 2020, March 7. Prairie spotting: How to identify remnant habitats and pockets of biodiversity on an altered landscape. Presented to ReLeaf Chatham-Kent, Chatham, Ontario.
Van Hemessen, W.D. 2019, May 22. The importance of land trusts in the modern era of conservation. Keynote address at the Thames Talbot Land Trust Annual General Meeting, London, Ontario.
Van Hemessen, W.D. 2019, January 21. A prairie ecology primer. Presented at the Natural City symposium, Toronto, Ontario.
Van Hemessen, W.D. 2017, April 26. Gardening with native plants. Presented to the Garden Club of London, London, Ontario.
Van Hemessen, W.D. and C. Beneteau. 2016, December 2. Environmental mitigation on construction sites. Presented to the St. Thomas Field Naturalists, St. Thomas, Ontario.
Van Hemessen, W.D. 2016, June 2. A three-year roadside mortality study of turtles. Presented at the 2016 Canadian Society of Civil Engineers conference, London, Ontario.
Van Hemessen, W.D. 2012, October 10. Exploring the effects of land use characteristics on flora at the urban-forest interface. Presented at the 39th annual Natural Areas Association conference, Norfolk, Virginia.
Van Hemessen, W.D. 2012, April 27. Edge effects in urban woodlands: the influence of adjacent land use type. Presented at the 9th annual Earth Day colloquium, University of Western Ontario, London, Ontario.
CONTACT WILLIAM
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