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Location Portugal, Alentejo,Lisboa e Vale do Tejo
Central coordinates 8o 56.00' West  38o 49.00' North
IBA criteria A1, A4i, A4iii, B1i, B2, C1, C2, C3, C4, C6
Area 45,071 ha
Altitude 0 - 43m
Year of IBA assessment 2002

Sociedade Portuguesa para o Estudo das Aves

Site description The largest wetland and estuary in Portugal, and one of the mainest in Europe, in extension and in natural value. Located in central Portugal, the site includes the upper and central parts of the River Tejo estuary and the valley of a small tributary (Ria Enguias). The site presents large expanses of mudflats and saltmarshes as result of soft slopes at its edges and its wideness of tide. At the edges of the IBA rice-fields are found and also an extensive area for agriculture and cattle-breed. Lisbon is located at the mouth of the River Tejo, and more than two million people live around this IBA.

Key Biodiversity The site holds 100,000 or more wintering waterbirds on a regular basis, and is the most important locality in Portugal for wintering flamingos, ducks, waders and gulls. The area also holds important numbers of a wide variety of breeding waterbirds. The reedbeds in the upper part of the estuary support large numbers of migrating passerines during autumn. The wintering population of Tetrax tetrax is significant at national level and represents near 1% of wintering european population. 46 of the near 200 species that occur here are included in Anex I of 79/409/CEE directive.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Greylag Goose Anser anser winter  2002  2,500-4,350 individuals  good  A4i, B1i, C3  Least Concern 
Eurasian Wigeon Mareca penelope winter  2002  2,100-9,950 individuals  good  A4i, B1i, C3  Least Concern 
Common Teal Anas crecca winter  2002  4,800-25,500 individuals  good  A4i, B1i, C3  Least Concern 
Greater Flamingo Phoenicopterus roseus winter  2002  450-6,000 individuals  good  A4i, B1i, C2, C6  Least Concern 
White Stork Ciconia ciconia resident  2001  50-100 breeding pairs  medium  B2, C6  Least Concern 
Eurasian Spoonbill Platalea leucorodia winter  2002  90-190 individuals  good  A4i, B1i, C6  Least Concern 
Ixobrychus minutus breeding  2001  rare  C6  Not Recognised 
Purple Heron Ardea purpurea breeding  2000  150-200 breeding pairs  good  A4i, B1i, B2, C6  Least Concern 
Egretta garzetta resident  2002  common  C6  Not Recognised 
Western Marsh-harrier Circus aeruginosus breeding  2001  29-32 breeding pairs  good  C6  Least Concern 
Montagu's Harrier Circus pygargus breeding  2001  2-3 breeding pairs  good  C6  Least Concern 
Black-winged Kite Elanus caeruleus resident  1996  6-10 breeding pairs  medium  B2, C6  Least Concern 
Booted Eagle Hieraaetus pennatus breeding  1996  5-10 breeding pairs  poor  C6  Least Concern 
Western Marsh-harrier Circus aeruginosus winter  1999  142-165 individuals  good  C6  Least Concern 
Little Bustard Tetrax tetrax winter  2001  140-150 unknown  medium  A1, C1, C6  Near Threatened 
Himantopus himantopus breeding  1996  500-750 breeding pairs  good  C6  Not Recognised 
Pied Avocet Recurvirostra avosetta winter  2002  3,950-8,600 individuals  good  A4i, B1i, B2, C2, C6  Least Concern 
Charadrius alexandrinus winter  2002  640-2,500 individuals  good  A4i, B1i, C3  Not Recognised 
Charadrius alexandrinus breeding  2002  150-200 breeding pairs  medium  B2  Not Recognised 
Grey Plover Pluvialis squatarola winter  2002  1,200-3,150 individuals  good  A4i, B1i, C3  Least Concern 
Black-tailed Godwit Limosa limosa winter  2002  30,000-80,000 individuals  good  A4i, B1i, B2, C3  Near Threatened 
Dunlin Calidris alpina winter  2002  6,000-23,500 individuals  good  A4i, B1i, B2, C3  Least Concern 
Collared Pratincole Glareola pratincola breeding  2000  100-250 breeding pairs  medium  A4i, B1i, B2, C2, C6  Least Concern 
Little Tern Sternula albifrons breeding  2002  12-19 breeding pairs  good  C6  Least Concern 
Common Barn-owl Tyto alba winter  2002  abundant  B2  Least Concern 
Short-eared Owl Asio flammeus winter  2002  14-40 individuals  medium  C6  Least Concern 
European Nightjar Caprimulgus europaeus breeding  2001  frequent  C6  Least Concern 
Calandra Lark Melanocorypha calandra resident  2002  frequent  C6  Least Concern 
Greater Short-toed Lark Calandrella brachydactyla breeding  2002  common  C6  Least Concern 
Bluethroat Luscinia svecica winter  2001  frequent  C6  Least Concern 
A4iii Species group - waterbirds winter  2002  50-249 individuals  unknown  A4iii, C4   

IBA Monitoring

2005 low not assessed not assessed
Good - based on reliable and complete / representative data

Transportation and service corridors utility & service lines happening now small area/few individuals (<10%) very rapid to severe deterioration low

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Estuário do Tejo Nature Reserve 14,192 protected area contained by site 14,192  
Estuário do Tejo Wetlands of International Importance (Ramsar) 14,563 protected area contained by site 14,563  


IUCN habitat Habitat detail Extent (% of site)
Forest Broadleaved evergreen woodland  15%
Wetlands (inland) Rivers and streams; Water fringe vegetation  -
Artificial - terrestrial Arable land; Forestry plantations  20%
Coastline Lagoons; Mud flats & sand flats; Salt marshes; Tidal rivers & enclosed tidal waters  -

Land use

Land-use Extent (% of site)
agriculture -
fisheries/aquaculture -
forestry -
hunting -
nature conservation and research -
urban/industrial/transport -
water management -

Protection status National Nature Reserve (Estuário do Tejo, 14,192 ha covered by Nature Reserve); Special Protection Area (Estuário do Tejo, 45,071 ha covered by Special Protection Area). International Special Protection Area (Estuário do Tejo, 45,071 ha covered by Special Protection Area); Ramsar Site (Estuário do Tejo, 14,563 ha of IBA covered by Ramsar Site ).

References Costa & Guedes (1996), Farinha et al. (2001).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Tejo estuary. Downloaded from on 27/10/2016

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