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Location Netherlands, Friesland
Central coordinates 5o 55.00' East  53o 2.00' North
IBA criteria A4i, A4iii, B1i, B2, C2, C3, C4, C6
Area 1,260 ha
Year of IBA assessment 2000

Vogelbescherming Nederland

Site description An area of former peat-workings comprising open water, reedbeds, shrubs and wet meadows, located to the north of the city of Heerenveen. Human activities include reed-harvesting (`Other' land-use, below). This site, together with site 055, formed part of a single, larger site (former site NL023) in the previous pan-European IBA inventory (Grimmett and Jones 1989).

Key Biodiversity An important roost for geese Anser from surrounding feeding areas.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Greater White-fronted Goose Anser albifrons winter  1990-1994  35,173 individuals  good  A4i, B1i, C3  Least Concern 
Barnacle Goose Branta leucopsis winter  1990-1994  3,430 individuals  good  A4i, B1i, B2, C2  Least Concern 
Black Tern Chlidonias niger breeding  1992-1993  62 breeding pairs  medium  B2, C2, C6  Least Concern 
A4iii Species group - waterbirds winter  1994  20,000-49,999 individuals  unknown  A4iii, C4   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
De Deelen Nature Conservation Law 349 protected area contained by site 1,158  
De Deelen Wetlands of International Importance (Ramsar) 520 protected area contained by site 520  


IUCN habitat Habitat detail Extent (% of site)
Forest Alluvial and very wet forest  10%
Wetlands (inland) Standing freshwater; Water fringe vegetation  90%

Land use

Land-use Extent (% of site)
agriculture 5%
other 5%
fisheries/aquaculture 50%
water management 100%
nature conservation and research 92%
tourism/recreation 20%
hunting 20%

Protection status National High International Partial1,158 ha of IBA covered by Nature Reserve (De Deelen, 1,158 ha). 520 ha of IBA covered by Special Protection Area (De Deelen, 520 ha). 520 ha of IBA covered by Ramsar Site (De Deelen, 520 ha).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: De Deelen. Downloaded from on 21/10/2016

To provide new information to update this factsheet or to correct any errors, please email BirdLife