Wormer- en Jisperveld & Kalverpolder

IBA Criteria

Year of most recent IBA criteria assessment: 2016

Populations of IBA trigger species
Species Current IUCN Red List Category Season Year(s) of estimate Population estimate IBA Criteria Triggered
Barnacle Goose Branta leucopsis LC breeding 2009-2014 1,181 breeding pairs B3, C2, C6
Eurasian Bittern Botaurus stellaris LC breeding 2011-2015 11 breeding pairs C6
Northern Lapwing Vanellus vanellus NT winter 2011-2015 4,357 individuals B2
Black-tailed Godwit Limosa limosa NT non-breeding 2011-2015 2,032-2,465 individuals B1i, C3
Ruff Calidris pugnax LC breeding 2011-2015 2 breeding pairs C6
A4iii Species group - waterbirds n/a non-breeding 2011-2015 29,063-36,628 individuals A4iii, C4

Note: This table presents the IBA criteria triggered and the species that triggered then at the time of assessment, the current IUCN Red List category may vary from that which was in place at that time.

For more information about the IBA assessment process and criteria please click here

IBA Monitoring

Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2018 high not assessed high
Was the whole site covered? Yes State assessed by unset
Accuracy of information medium

Threats to the site (pressure)
Threat Level 1 Threat Level 2 Timing Scope Severity Result
Agricultural expansion and intensification livestock farming and ranching (includes forest grazing) - agro-industry grazing, ranching or farmin happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications dams & water management/use - abstraction of ground water (agricultural use) happening now majority/most of area/population (50-90%) slow but significant deterioration high
Natural system modifications other ecosystem modifications happening now some of area/population (10-49%) slow but significant deterioration medium

Conservation actions taken at site (response)
Conservation Designation Management Planning Conservation Action Result
Whole area of site (>90%) covered by appropriate conservation designation A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species The conservation measures needed for the site are being comprehensively and effectively implemented high
For more information about IBA monitoring please click here

IBA Protection

Protected Area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)
Wormer- en Jisperveld & Kalverpolder Natuurbeschermingswet 1,839 protected area contains site 1,750
Wormer- en Jisperveld & Kalverpolder Site of Community Importance (Habitats Directive) 1,453 protected area overlaps with site 1,503
Wormer- en Jisperveld & Kalverpolder Special Protection Area (Birds Directive) 1,743 is identical to site 1,753
Wormer- En Jisperveld Nature Reserve 642 protected area contained by site 642


IUCN Habitat Habitat detail Extent (% of site)
Wetlands (inland) Standing freshwater, Water fringe vegetation -
Artificial/Terrestrial Highly improved re-seeded landscapes -
For further information about the habitat classification please click here.

Land use

Land-use Extent (% of site)
agriculture -
fisheries/aquaculture -
water management -
hunting -
nature conservation and research -
tourism/recreation -
For further information about the land use classification please click here.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Wormer- en Jisperveld & Kalverpolder. Downloaded from on 15/08/2022.