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Location Netherlands, Noord-Holland
Central coordinates 4o 56.00' East  52o 27.00' North
IBA criteria A4i, A4iii, B1i, B2, C3, C4, C6
Area 1,960 ha
Year of IBA assessment 2000

Vogelbescherming Nederland

Site description A polder complex comprising pools, ditches, marshland, wet meadows, improved grassland and a recreational area (Twiske). The IBA is located to the north of the city of Amsterdam, adjacent to Oostzanerveld (072). This site, together with sites 068, 070 and 072, formed part of a single, larger site (former site NL038) in the previous pan-European IBA inventory (Grimmett and Jones 1989).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Eurasian Wigeon Mareca penelope winter  1988-1993  21,526 individuals  medium  A4i, B1i, C3  Least Concern 
Eurasian Bittern Botaurus stellaris resident  1987-1991  7 breeding pairs  good  B2, C6  Least Concern 
Black-tailed Godwit Limosa limosa non-breeding  1990-1992  9,850 individuals  medium  A4i, B1i, C3  Near Threatened 
Ruff Calidris pugnax breeding  1987-1991  20 breeding pairs  good  C6  Least Concern 
A4iii Species group - waterbirds winter  1993  20,000-49,999 individuals  unknown  A4iii, C4   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Varkensland Nature Reserve 531 protected area contained by site 531  
Waterland Varkensland Natural Monument 315 protected area contained by site 315  


IUCN habitat Habitat detail Extent (% of site)
Forest Mixed woodland  5%
Wetlands (inland) Standing freshwater; Water fringe vegetation  22%
Artificial - terrestrial Highly improved re-seeded landscapes  70%

Land use

Land-use Extent (% of site)
agriculture 40%
fisheries/aquaculture 5%
water management 100%
hunting 70%
nature conservation and research 100%
tourism/recreation 8%

Protection status National Partial International None315 ha of IBA covered by Natural Monument (Waterland Varkensland, 315 ha). 531 ha of IBA covered by Nature Reserve (Varkensland, 531 ha).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Ilperveld, Varkensland and Twiske. Downloaded from on 25/10/2016

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