Atlas of nesting birds in Bulgaria

Slender-billed Gull

(Larus genei)

Category of conservation concern (IUCN, 2020) – Least Concern

Population size: 2020: 0-6 pairs (2007: 0-2 pairs)

Distribution pattern

With two breeding sites near the Black Sea, in the hypersaline Atanasovsko and Pomorie Lakes, where the species remain during the whole breeding season, but does not breed every year and even after starting to nest does not always succeed to raise offspring. For the first time, although unsuccessful, breeding has been observed on June 11, 1996 at the Atanasovsko Lake. On July 6, 2004, four specimens were observed there, showing breeding behaviour. In May and on June 2, 2005 from 26 to 40 specimens were copulating and sitting as if incubating on a dike at Pomorie Lake, but on July 12, 2005 no juveniles or adults were found at the site. Single specimens remain during the breeding season also at the Durankulak Lake and Shabla Tuzla, as well as at some marshes along the Danube River.

Population estimation for the period 2013 – 2020:  In 2012, for the second time (after 1996), the species was confirmed to breed in Bulgaria. After that, the presence of the Slender-billed Gull during the breeding season in the Burgas lakes became more frequent. During the study period was established, that the species breeds periodically in the Atanasovsko and Pomorie lakes. There are probably more attempts at breeding, but many are compromised due to predation, disturbance or other factors.

Population size in Special Protection Areas of Natura 2000: 0-6 pairs (100% of the population). The entire breeding population of the species is found on the territory of the Natura 2000 network. It breeds only in the Special Protection Areas “Atanasovsko Lake” (0-6 pairs) and “Pomorie Lake” (0-5 pairs).

Big size map

Breeding distribution 2013 – 2020 – The distribution and the estimation of the population size of the species for the period 2013 – 2020 is presented –

Comparative distribution of the species compared to the first breeding birds atlas (Iankov, 2007): Breeding locality until 2007 | Breeding locality until 2007, confirmed after 2015 – | New breeding locality after 2015. – The breeding localities after 2015 are identified on a base of raw data from


Breeds in salty or hypersaline coastal lagoons (on dikes in saltpans). During the breeding season is also found around standing brackish waters. 

Trends in population changes for the period 2013-2020

Short-term trend of population size:


Long-term trend of population size:


Short-term trend of distribution:


Long-term trend of distribution:



Predation threatening eggs and chicks in breeding colonies. Extreme climate events because of global climate change. Destruction of nests and chicks due to technical activities in the production and extraction of salt.

Vladimir Mladenov, Ralitsa Georgieva, Petar Shurulinkov