Country/territory: Netherlands

IBA Criteria met: A4i, A4iii, B1i, B2, B3, C2, C3, C4, C6 (2016)
For more information about IBA criteria please click here

Area: 9,478 ha

Vogelbescherming Nederland
Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2018 low not assessed medium
For more information about IBA monitoring please click here

Site description
A former tidal estuary in the Rhine/Maas river system, sealed off from the sea in 1970 (see Haringvliet, 024) and no longer subject to marine influence. The site consists of a flood-plain, polders, marshland and swamp-forest, and is intersected by many formerly tidal creeks. The site is adjacent to Hollands Diep (025) in the west; it does not include three drinking-water reservoirs within its boundary. Human activities include reed-harvesting (`Other' land-use, below).

Key biodiversity
An important roost for geese Anser which come from surrounding feeding areas, but counts underestimate actual numbers. The mean total number of waterbirds in January exceeds 20,000.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Biesbosch. Downloaded from on 23/01/2022.