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Location Portugal, Lisboa e Vale do Tejo
Central coordinates 9o 2.00' West  38o 52.00' North
IBA criteria B2, C6
Area 218 ha
Altitude 0 - 5m
Year of IBA assessment 2002

Sociedade Portuguesa para o Estudo das Aves

Site description This site is located at north bank of Tejo Estuary. Is formed by two salinas (salt pans) complexes: Salinas de Alverca and Salinas do Forte da Casa, extensive agricultural landscapes that separe them, and the final part of Verdelha river; it represents the only bird refuge in this riverbank. In the surrounding zone, the strongly built up and industrializated area of Alberca contrasts with the Natural Reserve of Tejo Estuary and Portuguese Air-Force installations. Besides the salinas banks and landscapes, there are also drainage trenchs and a stream with an important water fringe vegetation. Now, salinas are abandoned and water lever is conditioned by precipitation. Vegetation inside the banks is mainly constituted by aquatic plant, namely rushes and reeds. In the edges salt-marshes vegetation and rarely tamarisks are found.

Key Biodiversity The salinas of Alberca and Forte da Casa costitute one of the most important nesting site in Tejo Estuary for aquatic-birds like Himantopus himantopus whose colonny could ever hold thousands of breeding pairs. This is the only nesting place of Netta rufina in estuary. Circus aeruginosus, Recurvirostra avosetta, Glareola pranticola, Sterna albifrons and also Ixobrichus minutus, Anas strepera, Fulica atra are present here in significative numbers. The whole zone is important as feeding area for Ardea purpurea and C.aeruginosus who breed in Natural Reserve; and also for passerines and waders during wintering or migration seasons.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Greater Flamingo Phoenicopterus roseus winter  2000  1-100 individuals  good  C6  Least Concern 
Purple Heron Ardea purpurea breeding  2001  common  C6  Least Concern 
Western Marsh-harrier Circus aeruginosus resident  1998  common  C6  Least Concern 
Himantopus himantopus resident  2001  40-300 breeding pairs  good  C6  Not Recognised 
Himantopus himantopus winter  2001  1-50 individuals  good  C6  Not Recognised 
Pied Avocet Recurvirostra avosetta resident  2001  1-2 breeding pairs  good  C6  Least Concern 
Pied Avocet Recurvirostra avosetta winter  2001  10-100 individuals  medium  C6  Least Concern 
Collared Pratincole Glareola pratincola breeding  2001  10-40 breeding pairs  good  B2, C6  Least Concern 
Little Tern Sternula albifrons breeding  2000  frequent  C6  Least Concern 

IBA Monitoring

2012 very high not assessed negligible
Good - based on reliable and complete / representative data

Residential and commercial development commercial and industrial development happening now majority/most of area/population (50-90%) very rapid to severe deterioration very high
Transportation and service corridors roads and railroads likely in short term (within 4 years) some of area/population (10-49%) moderate to rapid deterioration medium

Little/none of site covered (<10%)  No management planning has taken place  Very little or no conservation action taking place  negligible 


IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Rivers and streams; Standing brackish and salt water; Standing freshwater; Water fringe vegetation  -
Artificial - terrestrial Arable land; Other urban and industrial areas  -
Shrubland Sclerophyllous scrub, garrigue and maquis  -

Land use

Land-use Extent (% of site)
agriculture -
hunting -
military -
tourism/recreation -
urban/industrial/transport -
water management -

Protection status National:NoneInternational:None

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Salinas de Alverca e do Forte da Casa. Downloaded from on 23/10/2016

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