- Sternula albifrons (Pallas, 1764)
Be (II); Bo (AEWA); EUBD (I); RDBUkr: Рідкісні
Value of species
Sternula albifrons (del Hoyo and Collar 2014) was previously placed in the genus Sterna.
Breeding populations of the Little Tern can be found through much of Europe, scattering along the coast and inland in parts of Africa, in much of western, central and the extreme east and south of Asia, and in northern parts of Australasia. Migratory individuals expand the range to include most of the coast of Africa, the Arabian Peninsula, the western coast of India and most of the waters of south-east Asia and Australasia, including New Zealand. One seasonally breeding colony is also present on Hawaii (del Hoyo et al. 1996).
The global population is estimated to number c.190,000-410,000 individuals (Wetlands International 2006), while national population estimates include: c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in China; c.100-10,000 breeding pairs, c.50-1,000 individuals on migration and c.50-1,000 wintering individuals in Taiwan; c.100-10,000 breeding pairs and c.50-1,000 individuals on migration in Korea and c.100-10,000 breeding pairs and c.50-1,000 individuals on migration in Japan (Brazil 2009).
Trend Justification: The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2006).
Behaviour The Little Tern is a strongly migratory (del Hoyo et al. 1996) coastal seabird which usually fishes in very shallow water only a few centimetres deep, often over the advancing tideline or in brackish lagoons and saltmarsh creeks. It has the most inshore distribution of all terns. It breeds between May and July (Richards 1990) in solitary pairs (Flint et al. 1984) or small monospecific groups (del Hoyo et al. 1996) usually of 1-15 pairs (del Hoyo et al. 1996, Snow and Perrins 1998) (rarely over 40 pairs) (del Hoyo et al. 1996) occasionally amidst colonies of other terns (Flint et al. 1984). Breeding may be timed to coincide with peak fish abundance (Perrow et al 2006). Northern breeders depart the breeding grounds from late-July onwards (Richards 1990, del Hoyo et al. 1996), travelling first to moulting sites where they form large roosts before continuing southwards (Tavecchia et al. 2006). The species is gregarious throughout the year (Snow and Perrins 1998) and usually feeds singly, in small groups or larger scattered flocks (Snow and Perrins 1998) and congregating in many thousands on passage in small wetlands where fish fry are abundant (del Hoyo et al. 1996). Habitat Breeding The species breeds on barren or sparsely vegetated beaches, islands and spits of sand, shingle (del Hoyo et al. 1996), shell fragments, pebbles (Flint et al. 1984), rocks or coral fragments (del Hoyo et al. 1996) on seashores (Flint et al. 1984) or in estuaries, saltmarshes, saltpans, offshore coral reefs (del Hoyo et al. 1996), rivers, lakes (Flint et al. 1984, del Hoyo et al. 1996) and reservoirs (de Silva 1991). It may also nest on dry mudflats in grassy areas (de Silva 1991, del Hoyo et al. 1996) but shows a preference for islets surrounded by saline or fresh water where small fish can be caught without the need for extensive foraging flights (Snow and Perrins 1998). Non-breeding Outside of the breeding season the species frequents tidal creeks, coastal lagoons and saltpans and may foraging at sea (del Hoyo et al. 1996) up to 15 km offshore (Urban et al. 1986). Diet Its diet consists predominantly of small fish (e.g. Ammodytes spp., roach Rutilus rutilus, rudd Scardinius erythrophthalmus, carp Cyprinus carpio and perch Perca fluviatilis) and crustaceans 3-6 cm long as well as insects, annelid worms and molluscs (del Hoyo et al. 1996). In Scotland, Little Terns feed mainly on small fish and invertebrates, including herring, sandeel, and shrimps (Crangon vulgaris) (BirdLife International 2000). In Portugal, birds were found to feed mainly on sand-smelts (Atherina spp.) and gobies (Pomatoschistus spp.), which were the most abundant fish species in the study areas (Catry et al 2006). On Rigby Island, Australia, chicks were fed entirely on juvenile fish of the families Clupeidae, Engraulidae, Pomatomidae and Carangidae, including pilchard, southern anchovy and blue sprat (Taylor and Roe 2004). Breeding site The nest is a bare scrape (Richards 1990) positioned on the ground in less than 15 % vegetation cover (del Hoyo et al. 1996) on beaches of sand, pebbles, shingle, shell fragments, coral fragments or rock (Flint et al. 1984, del Hoyo et al. 1996) above the high tide-line and often only a few metres away from shallow clear water (Snow and Perrins 1998). Alternatively in more marshy habitats (e.g. coastal saltmarshes) the species may build a nest of shells or vegetation (del Hoyo et al. 1996). The species nests in small loose colonies, with neighbouring nests usually placed more than 2 m apart (del Hoyo et al. 1996). Foraging range In Spain, 95% of foraging terns were observed less than 4 km away from the nearest colony (Bertolero et al 2005). However, the foraging range of individuals varies according to whether they are currently breeding. In Norfolk, UK, birds with an active nest occupied a range of <6.3 km2 with a range span of up to 4.6 km (Perrow et al 2006), whereas failed birds ranged widely, travelling up to 27 km in a single foraging bout (Perrow et al 2006). In Portugal, ranges were found to be significantly greater during incubation (April-May) than during chick rearing (June-July) (Paiva et al 2007). Little Terns prefer channels and lagoons for foraging, rather than deeper marine habitats (Bertolero et al 2005, Paiva et al 2007). They also prefer areas with abundant resources, entrance channels and main lagoon channels with strong currents, and areas with alternative feeding resources nearby (Paiva et al 2007). Areas subjected to strong human pressure (Paiva et al 2007) and salt marshes (Bertolero et al 2005) are avoided. The species tends to forage preferentially at low tide (Paiva et al 2007).
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