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Location Turkey, Istanbul
Central coordinates 29o 7.00' East  41o 7.00' North
IBA criteria A4i, A4ii, A4iii, A4iv, B1i, B1ii, B1iv
Area 55,240 ha
Altitude 0 - 409m
Year of IBA assessment 2004

Doga Dernegi (Partner Designate)

Site description The Boðaziçi strait runs north-south for c.33 km, and is c.1.5 km wide. The site includes the forested areas east (Polonezköy Nature Park) and west (Belgrade forest) of the strait, which are known to be of importance to roosting migrants. It does not include the çamlýca hills and the islands in the Sea of Marmara, which would qualify as an IBA in their own right due to the large numbers of migrants passing over, but which provide limited scope for bird conservation.

Key Biodiversity The site is a major migratory bottleneck, where more than 20,000 storks and raptors regularly pass in spring and autumn. Few counts covering the entire migration period have been undertaken. Total counts made in the mid-1960s and early 1970s and covering the entire autumn migration period are as follows: Ciconia nigra (8,318), Ciconia ciconia (338,353), Pernis apivorus (25,751), Milvus migrans (2,707), Buteo buteo (32,895) and Aquila pomarina (18,898). More recent autumn records include 11,703 Aquila pomarina at çamlýca and 11,379 of the same species at Sarýyer, both on the same day in September 1990. Ciconia sp. often roost in flocks of thousands in fields outside the city. Disturbance by Larus cachinnans and possibly pollution are thought to be behind a drastic decline in numbers of breeding Milvus migrans.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Yelkouan Shearwater Puffinus yelkouan non-breeding  2000  1,000-25,000 individuals  medium  A4ii, B1ii  Vulnerable 
Yelkouan Shearwater Puffinus yelkouan winter  1,377 individuals  A4ii, B1ii  Vulnerable 
Black Stork Ciconia nigra passage  8,000 individuals  A4i, B1i  Least Concern 
White Stork Ciconia ciconia passage  32,000-338,353 individuals  A4i, B1i  Least Concern 
Great Cormorant Phalacrocorax carbo winter  3,456-10,000 individuals  A4i, B1i  Least Concern 
European Shag Phalacrocorax aristotelis resident  2002  450 individuals  B1i  Least Concern 
Larus cachinnans winter  1999  40,000 individuals  A4i, B1i  Not Recognised 
Black-headed Gull Larus ridibundus winter  1999  15,040 individuals  B1i  Least Concern 
Mediterranean Gull Larus melanocephalus passage  2000  14,500 individuals  A4i, B1i  Least Concern 
A4iii Species group - waterbirds winter  20,310-22,644 individuals  A4iii   
A4iv Species group - soaring birds/cranes passage  92,000 individuals  A4iv, B1iv   

IBA Monitoring

2013 very high very unfavourable low
Medium - based upon reliable but incomplete / partially representative data

Residential and commercial development housing and urban areas happening now majority/most of area/population (50-90%) very rapid to severe deterioration very high
Transportation and service corridors flight paths likely in short term (within 4 years) majority/most of area/population (50-90%) moderate to rapid deterioration high
Transportation and service corridors roads and railroads happening now majority/most of area/population (50-90%) very rapid to severe deterioration very high

Puffinus yelkouan Yelkouan Shearwater 1980 1040 - 53 unfavourable
Ardea cinerea Grey Heron 30 2 - 7 very unfavourable
Phalacrocorax carbo Great Cormorant 9531 4245 - 45 unfavourable
Species group - waterbirds A4iii 50744 50744 adults only 100 favourable

Whole area of site (>90%) covered by appropriate conservation designation  No management planning has taken place  Very little or no conservation action taking place  low 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Bogazici SIT (Law on Protection of Cultural and Natural Assets No. 2863) 0 protected area contained by site 0  
Polonezköy Nature Park 3,004 protected area contained by site 2,931  
Sariyer Game Reserve 2,338 protected area contained by site 1,451  


IUCN habitat Habitat detail Extent (% of site)
Forest Mixed woodland  30%
Sea Sea inlets and coastal features  10%
Artificial - terrestrial Other urban and industrial areas  60%

Land use

Land-use Extent (% of site)
agriculture 5%
urban/industrial/transport 60%
tourism/recreation 20%
military 5%
forestry 15%

Protection status National Partial International None3,006 ha of IBA covered by Nature Park (Polonezköy, 3,006 ha). 2,338 ha of IBA covered by Permanent Wildlife Reserve (Sarýyer, 2,338 ha). 5,296 ha of IBA covered by Preservation Forest (Belgrad Ormaný, 5,296 ha). IBA also overlaps with SÝT (Boðaziçi).

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Recommended citation  BirdLife International (2015) Important Bird and Biodiversity Area factsheet: Bosphorus. Downloaded from on 25/11/2015

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