Project Report
| Apr 13, 2026
Annual Report - Griesbroek Nature Reserve
By Dirk Geenen | Reserve team member
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Annual Report – Griesbroek Nature Reserve
Work Activities
- Biweekly Saturday work sessions (9:00–12:00): This year’s main focus was maintaining the developing heathland at the “Ezelwei” and around the pond. Volunteers removed brambles and birch seedlings, invested significant time in maintaining the walking paths, and continued efforts to control invasive species, particularly Ludwigia.
- Litter cleanups: Three littercollection actions were carried out as part of the municipal antilitter campaign.
- Guided walks: The primary school of Hulsen visited three times for guided nature walks.
- Youth engagement: As part of their annual tradition, students from secondary school ’t Spoor participated in a workday to conclude their second trimester.
- Corporate volunteering: Koen Meynen and his team organised a teambuilding workday in the reserve.
- Day of Nature – 22 November: One additional volunteer joined the activity this year.
Monitoring & Research
- Winter waterbird counts
- Monitoring networks:
o Melitaea cinxia
o Calopteryx virgo
- INBO collaboration: Monitoring of Lota lota larvae.
- Moth monitoring (20 June): The butterfly working group conducted a nocturnal moth survey. Using light traps, they recorded 140 different species in just three hours.
- Biweekly groundwater measurements in monitoring wells.
Biodiversity observations (past year)
- 3,504 observations
- 5,941 individual organisms
- 778 different species recorded
Top 3 observers in 2025
- Marc Mangelschots – 250 species
- Helga Ferket – 222 species
- Koen Meynen – 207 species
Cumulative total
Across all years, 2,688 species have been recorded in Griesbroek.
Notable sightings
- Firstever colony of Ammophila sabulosa
- Spoonbills and Black Stork making brief stopovers during migration
- Bewick’s Swan
- The pair of White Storks nesting at the edge of the reserve successfully raised two chicks this year.
In Memoriam
On 25 January, we said goodbye to René Wils, a valued and longstanding member of our reserve management team.
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