Justification of Red List Category
This species has an extremely 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 stable, 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 is very large, and hence does not 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 overall population trend is stable, although some populations have unknown trends (Delany and Scott 2006).
The Lesser Crested Tern breeds in subtropical coastal parts of the world mainly from the Red Sea across the Indian Ocean to the western Pacific, and Australia, with a significant population on the southern coast of the Mediterranean, on two islands off the coast of Libya. Outside the breeding season it ranges on the north African coast (both Mediterranean and Atlantic), on much of the Indian Ocean nearby continents, and in the western Pacific north of Australia up to New Guinea and Vietnam.
Behaviour The details of this species's movements are poorly known although some breeding populations appear to be migratory (del Hoyo et al. 1996). The species breeds in large dense colonies of up to 20,000 pairs (del Hoyo et al. 1996) often with other species (del Hoyo et al. 1996). It is gregarious throughout the year, foraging in single- or mixed-species flocks up to 400 individuals (del Hoyo et al. 1996, Snow and Perrins 1998). Habitat The species inhabits tropical and subtropical (del Hoyo et al. 1996) sandy and coral coasts and estuaries (Urban et al. 1986), breeding on low-lying offshore islands, coral flats, sandbanks (del Hoyo et al. 1996) and flat sandy beaches (Snow and Perrins 1998), foraging in the surf and over offshore waters (del Hoyo et al. 1996). Diet Its diet consists predominantly of small pelagic fish (Urban et al. 1986, del Hoyo et al. 1996) and shrimps (del Hoyo et al. 1996). Breeding site The nest is a shallow scrape (del Hoyo et al. 1996) on ridges or bare areas surrounded by vegetation (del Hoyo et al. 1996) on flat sandy beaches (Snow and Perrins 1998), low-lying sandy islands, coral flats, small coral islets and sandbanks (del Hoyo et al. 1996).
At present there are no factors thought to pose a genuine threat to this species.
Text account compilers
Butchart, S., Malpas, L., Calvert, R., Stuart, A., Ekstrom, J.
BirdLife International (2021) Species factsheet: Thalasseus bengalensis. Downloaded from http://www.birdlife.org on 31/07/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/07/2021.