Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be small, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The population is estimated to number 1,000-10,000 individuals.
The population is suspected to be increasing following a reduction in persecution (del Hoyo et al. 1996).
Larus belcheri is found along the Pacific coast of South America, from Ecuador to central Chile, breeding primarily from northern Chile to north Peru (del Hoyo et al. 1996).
This species occurs on rocky shores and inshore on guano islands. It feeds on fish, crabs, shellfish and carrion, as well as seabird eggs and young which are important in the breeding season. It feeds along beaches and around bird colonies, scavenging in the intertidal zone. Breeding begins in December in scattered, usually small colonies (100 pairs). It nests in hollows among rocks or on sand on the shore close to the high tide line (del Hoyo et al. 1996).
The species' population is currently increasing. It does face some threats from disturbance from tourist visitation to areas coastal areas where this species breeds is known to decrease breeding success and to potentially cause nest desertion in this species. Though, as for the threat of commercial expansion in coastal areas, this threat has diminished in response to the declaring of national parks for the majority of this species' range (Burger et al. 2018). Development of coastal areas in Peru and Chile, where colonies of this species are situated, is leading to much habitat loss and increased disturbance during the breeding season. While the extent of this has decreased in recent years, as more areas have been declared national parks, this threat remains significant outside of these protected zones (Yorio et al. 2013).
Text account compilers
Calvert, R., Butchart, S., Ekstrom, J.
BirdLife International (2019) Species factsheet: Larus belcheri. Downloaded from http://www.birdlife.org on 21/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/09/2019.