Chlidonias albostriatus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Laridae

Scientific Name: Chlidonias albostriatus (Gray, 1845)
Common Name(s):
English Black-fronted Tern
Spanish Charrán fumarel
Chlidonias albostriatus (Gray, 1845) — Collar and Andrew (1988)
Chlidonias albostriatus (Gray, 1845) — Collar et al. (1994)
Chlidonias albostriatus (Gray, 1845) — Sibley and Monroe (1990, 1993)
Hydrochelidon albostriata Gray, 1845
Sterna albostriata (Gray, 1845)
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Taxonomic Notes: Chlidonias albostriatus (del Hoyo and Collar 2014) was previously placed in the genus Sterna as S. albostriata.

Identification information: 29 cm. Small, grey tern with black cap. Grey body and wings. Short, forked tail. White underparts. In flight, contrasting white rump. Bright orange legs, bill. Breeding adult, black cap extending to bill. Thin white line along cheek. Non-breeding adult, grey-flecked crown reduced to arc from eye to eye. Juvenile, similar except black-flecked crown, white chin. Similar spp. Whiskered Tern Chlidonias hybrida has even grey on rump. Little Tern S. albifrons has dark primaries on upper wings, yellow bill. Fairy Tern S. nereis has yellow-orange bill. White-fronted Tern S. striata, Common Tern S. hirundo are larger with black bill, legs. Voice Call repetitive kit.

Assessment Information [top]

Red List Category & Criteria: Endangered A2bce+3bce+4bce ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bell, B., Bell, M., Dowding, J., Grant, A., Hitchmough, R., Keedwell, R., Szabo, M. & Taylor, G.
Facilitator/Compiler(s): Anderson, O., Benstead, P., Bird, J., Butchart, S., Calvert, R., Mahood, S., McClellan, R., Pilgrim, J. & Taylor, J.
This tern has a small population which has shown recent very rapid population reductions at some wintering and breeding sites, which are predicted to continue in the future owing to on-going threats. It is therefore considered Endangered.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Chlidonias albostriatus breeds in the South Island, New Zealand. It is found along the eastern riverbeds from Marlborough to Southland, and on the upper Motueka and Buller Rivers in southern Nelson (Heather and Robertson 1997). Birds disperse to the coastline and estuaries in winter, mostly from Stewart Island to the southern North Island, feeding at sea within 10 km of the coast (Heather and Robertson 1997, Taylor 2000). The most recent estimates put the total population at 7,000-10,000 individuals (R. Keedwell in litt. 2006) or 5,000 individuals (per M. Bell in litt. 2012). All populations of this species that have been studied have been in decline (G. A. Taylor in litt. 1999). Numbers recorded in the Bay of Plenty during winters in the 1980s ranged between 25 and 45 individuals. Since 2000, counts at the same site have varied between 10 and 16 individuals (M. Szabo in litt. 2006). Similarly, on the breeding grounds numbers on the Ashburton River declined from over 750 birds in 1981 to fewer than 200 by 1990 (O'Donnell 1992, Maloney 1999, Taylor 2000). A total of 55 individuals was recorded in the lower 18 km of the Ashley River in 1980 (Wildlife Service surveys), with just 26-28 along the same stretch in 2005-2006 (J. Dowding in litt. 2006). These and other observations indicate that the species may be in widespread decline (O'Donnell 1992, Maloney 1999, Taylor 2000, M. Szabo in litt. 2006).

Countries occurrence:
New Zealand
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:161000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:11-100Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 2004, the New Zealand Department of Conservation estimated 1,000-5,000 mature individuals of this species (R. Hitchmough in litt. 2006), and a winter census in 2007 estimated c.5,000 individuals (per M. Bell in litt. 2012). Another estimate has put the total population at 7,000-10,000 individuals (R. Keedwell in litt. 2006), roughly equivalent to 4,600-6,700 mature individuals. Based on these estimates, the population is placed in the band for 2,500-9,999 mature individuals.

Trend Justification:  

Breeding populations on braided rivers in the South Island, New Zealand, are assumed to be in decline as their habitat comes under increasing pressure from exotic pests, hydroelectric power development and water abstraction. A meta analysis of the trends of the breeding population from 1962-2008 (O’Donnell and Hoare 2011) showed that rivers on which declines have occurred are characterised by having relatively low flows. At such rates, populations on low-flow rivers (51.4% of black-fronted terns counted on the oldest counts) would decline by a further c. 90% within 25 years.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:2500-9999Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It breeds on riverbeds, creating simple scrapes in the shingle. It usually lays two eggs. The young fledge after c.30 days. It feeds on freshwater invertebrates and small fish, taken as it forages over channels in gravelly rivers of South Island, occasionally taking earthworms and other invertebrates in terrestrial environments (on pastureland) and, when at sea, feeding mainly on crustaceans (Heather and Robertson 1997, O'Donnell and Hoare 2009). Adults in one colony fed their chicks 36-73 common skinks Oligosoma polychroma per hour (O'Donnell and Hoare 2009). 

Systems:Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):11
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): Introduced mustelids Mustela spp., feral cats, brown rats Rattus norvegicus, hedgehogs, brush-tailed possums Trichosurus vulpecula, dogs, Australian Magpies Gymnorhina tibicen and other native bird species prey on this species (Taylor 2000, Keedwell et al. 2002, M. Bell in litt. 2012). Major breeding failures have been recently reported at colonies as a result of predation (G. A. Taylor in litt. 1999, Keedwell et al. 2002). Cattle and sheep can disturb breeding colonies. Recreational activities, presently increasing rapidly, can cause breeding failure and disturbance at wintering sites. Further hydroelectric developments are a major threat; notably an approved project on the Wairau River where 12% of the population currently nest (M. Szabo in litt. 2006). Invasion of introduced weed species and tree planting along riverbeds reduces available habitat (Taylor 2000) and forces birds to nest in areas more prone to flooding (M. Bell in litt. 2012). Confinement of rivers to a single channel reduces the availability of nesting "islands" (B. D. Bell verbally 1999). The species may be threatened at its roosting sites by predation, disturbance and development (M. Bell in litt. 2012).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Several studies have been completed covering aspects of the species's biology and ecology. Habitat restoration and fauna monitoring is carried out by Project River Recovery in a number of major riverbed habitats in the McKenzie basin, covering part of the range (A. Grant in litt 1999, Taylor 2000). Some populations have received predator control measures with limited improvements to breeding success (M. Bell in litt. 2012).

Conservation Actions Proposed
Census and map all breeding colonies, and census winter flocks. Monitor accessible colonies annually. Examine all proposals for the development of hydroelectric dams or irrigation projects to identify impacts on the species. Establish nest protection if predation is identified as significantly affecting breeding success. Spray weeds on rivers if required (Taylor 2000), and commence a trial of establishing islands/rafts in lagoons and tarns (B. D. Bell verbally 1999).

Citation: BirdLife International. 2016. Chlidonias albostriatus. The IUCN Red List of Threatened Species 2016: e.T22694750A93468044. . Downloaded on 20 August 2018.
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