LC
Hartlaub's Gull Larus hartlaubii



Justification

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 moderately small to large, 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.

Trend justification
The overall population trend is increasing, although some populations have unknown trends (Delany and Scott 2006).

Distribution and population

Hartlaub's Gull is a non-migratory breeding resident endemic to the Atlantic Ocean coastline of South Africa and Namibia (del Hoyo et al. 1996).

Ecology

Behaviour This species is predominantly sedentary (Urban et al. 1986, del Hoyo et al. 1996, Hockey et al. 2005) although it may disperse short distances along the coast outside of the breeding season (del Hoyo et al. 1996, Hockey et al. 2005). Information about the timing of breeding is conflicting, although it appears to vary geographically, with the species breeding in any month of the year in some areas (del Hoyo et al. 1996). The species breeds in colonies of 10-1,000 pairs (Urban et al. 1986, del Hoyo et al. 1996), frequently with Greater Crested Terns Sterna bergii and other colonial species (Urban et al. 1986, Williams et al. 1990, del Hoyo et al. 1996). It remains gregarious outside of the breeding season, occurring in large groups (e.g. of 60 [Hockey et al. 2005] to several hundred [Urban et al. 1986] individuals) that forage and roost together (Urban et al. 1986, Hockey et al. 2005). Habitat The species inhabits coastal areas (del Hoyo et al. 1996), and is rarely seen further than 20 km from land (Williams et al. 1990) (usually observed within 3 km [Urban et al. 1986]). Suitable habitats include shallow inshore waters (Urban et al. 1986), where water is less than 50 m deep, estuaries, lagoons (Hockey et al. 2005), intertidal zones, beaches (Urban et al. 1986) and harbours (Urban et al. 1986, del Hoyo et al. 1996), also occurring on land at refuse dumps (del Hoyo et al. 1996), abattoirs (Urban et al. 1986, del Hoyo et al. 1996) and sewage and salt works (Urban et al. 1986, del Hoyo et al. 1996). It breeds on low, flat, rocky offshore islands (del Hoyo et al. 1996, Hockey et al. 2005), and is strongly associated with kelp beds (a large part of its diet consists of invertebrates associated with stranded kelp [Williams et al. 1990]). Diet Its diet consists predominantly of marine invertebrates (del Hoyo et al. 1996) (e.g. kelp fly larvae, amphipods [Urban et al. 1986], molluscs and crustaceans [Hockey et al. 2005]), especially those associated with stranded kelp (Williams et al. 1990), as well as terrestrial insects (del Hoyo et al. 1996) (e.g. crickets, grasshoppers, beetles, moths and ants [Hockey et al. 2005]), small fish (del Hoyo et al. 1996), earthworms (Urban et al. 1986, del Hoyo et al. 1996), the fruits of low-growing shrubs (Hockey et al. 2005), offal and refuse (Urban et al. 1986, del Hoyo et al. 1996, Hockey et al. 2005). Breeding site The species breeds colonially, with nests spaced 1-2 m (Urban et al. 1986, del Hoyo et al. 1996). Suitable sites include low, flat, rocky offshore islands (del Hoyo et al. 1996, Hockey et al. 2005) and artificial structures (Hockey et al. 2005) such as dykes in sewage lagoons and saltpans (Urban et al. 1986, del Hoyo et al. 1996) and the roofs of buildings (Urban et al. 1986, del Hoyo et al. 1996), although it does show a preference for bare or slightly vegetated ground (Urban et al. 1986, del Hoyo et al. 1996) (e.g. with beach halophytes [Urban et al. 1986]), that are associated with sites of more substantial vegetation (Urban et al. 1986). The nest is a slight hollow (Urban et al. 1986, del Hoyo et al. 1996) or a woven structure of plant stems (Hockey et al. 2005) that is typically placed on rocky surfaces (Urban et al. 1986, Hockey et al. 2005) or occasionally in reedbeds (Hockey et al. 2005), or up to 20-50 cm high in densely-matted sclerophyllous shrubs (Urban et al. 1986, del Hoyo et al. 1996).

Threats

The population is increasing and, although there are a number of sources of mortality such as egg predation and human disturbance, the species is not currently facing any threats that are thought to have a significant effect on the population.

Acknowledgements

Text account compilers
Calvert, R., Ekstrom, J., Butchart, S., Bennett, S., Malpas, L.


Recommended citation
BirdLife International (2020) Species factsheet: Larus hartlaubii. Downloaded from http://www.birdlife.org on 16/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/07/2020.