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Anous tenuirostris

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES CHARADRIIFORMES LARIDAE

Scientific Name: Anous tenuirostris
Species Authority: (Temminck, 1823)
Common Name(s):
English Lesser Noddy, Sooty Noddy
French Noddi marianne
Taxonomic Notes: Anous tenuirostris and A. minutus (Sibley and Monroe 1990, 1993), cross-regional species, are retained as separate species contra Turbott (1990) who includes minutus as a subspecies of tenuirostris.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Harding, M., Malpas, L.
Justification:
Although this species may have a small range, it is not believed to 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 extremely 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.

Geographic Range [top]

Range Description: This species breeds in the Seychelles, Mascarene Islands and Agalega Islands (Mauritius), Maldives, the Chagos Archipelago (British Indian Ocean Territory), and Houtman Albrolhos Islands and possibly Ashmore Reef (Australia) (Feare 1984, Higgins and Davies 1996). The Australian subspecies melanops may be resident. The nominate race is a winter visitor to Madagascar and the eastern African coast between southern Somalia and Kenya (Higgins and Davies 1996).
Countries:
Native:
Australia; British Indian Ocean Territory; Maldives; Mauritius; Oman; Seychelles; Tanzania, United Republic of; Tonga
Vagrant:
Comoros; Kenya; South Africa; Sri Lanka; United Arab Emirates
Present - origin uncertain:
French Southern Territories; Madagascar; Mayotte; Mozambique; Réunion
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The species has a large global population with an estimated minimum of 1,200,000 individuals (Wetlands International 2006). In the Seychelles, populations were estimated at 100,000 pairs on Cousin Island in 1974 and 18,000 pairs on Aride Island in 1972, and 250,000 pairs on Serpent Island in 19752 and 5,000 pairs on Lizard Island, Mauritius (Higgins and Davies 1996). In the Houtman Albrolhos, populations were estimated at 7,665, 6,325 and 34,895 pairs on Morley, Wooded and Pelsart Island respectively in 1993 (Higgins and Davies 1996).
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: This species is largely sedentary (del Hoyo et al. 1996) and remains at its breeding colonies throughout the year, although it may also forage extensively out to sea (Higgins and Davies 1996) and regularly occurs off the coast of East Africa during the non-breeding season (del Hoyo et al. 1996). It breeds from August to October (del Hoyo et al. 1996) in large colonies of up to tens of thousands of pairs (Higgins and Davies 1996, del Hoyo et al. 1996) and also forages in vast flocks during this season (Higgins and Davies 1996). When not breeding it remains gregarious and is usually observed in groups of up to 45 individuals (Higgins and Davies 1996), often within larger flocks of Brown Noddy Anous stolidus (Langrand 1990). The species breeds and roosts in mangroves on oceanic coral-limestone islands with shallow lagoons (providing seaweed as nesting material), gullies, sink holes and salt-lakes, and may also occur on shingle or sandy beaches (Higgins and Davies 1996, del Hoyo et al. 1996). It largely forages in inshore seas and reefs surrounding these breeding islands during the non-breeding season although it may also forage extensively out to sea (Langrand 1990, Higgins and Davies 1996). Diet consists of small surface-dwelling fish and invertebrates (e.g. squid) that have been driven to the surface by predatory fish (Feare 1984, Urban et al. 1986, Langrand 1990, Higgins and Davies 1996, del Hoyo et al. 1996). Prior to breeding, adults also consume large quantities of coral fragments from beaches as a source of calcium (needed for egg laying) (Skerrett et al. 2001). The nest is constructed of damp vegetation and seaweed in a low bush or on a horizontal or vertical fork of a tall mangrove tree (Higgins and Davies 1996, del Hoyo et al. 1996, Skerrett et al. 2001). It nests colonially, with neighbouring nests spaced between 0.3 and 5 m apart (del Hoyo et al. 1996).
Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): Habitat loss is a threat to tropical Indian Ocean islands where this species breeds, and introduced browsers and predators (e.g. rats) are present on several islands although their current impact is thought to be minimal (Feare 1984, Skerrett et al. 2001). In Australia, eggs, chicks and adults were taken for food last century by people harvesting guano (Higgins and Davies 1996).

Citation: BirdLife International 2012. Anous tenuirostris. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 02 October 2014.
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