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)
||del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
||Chlidonias albostriatus (del Hoyo and Collar 2014) was previously placed in the genus Sterna as S. albostriata.
||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.
|Red List Category & Criteria:
||Butchart, S. & Symes, A.
||Bell, B., Bell, M., Dowding, J., Grant, A., Hitchmough, R., Keedwell, R., Szabo, M. & Taylor, G.
||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:|
- 2012 – Endangered (EN)
- 2010 – Endangered (EN)
- 2008 – Endangered (EN)
- 2007 – Endangered (EN)
- 2004 – Endangered (EN)
- 2000 – Endangered (EN)
- 1996 – Vulnerable (VU)
- 1994 – Vulnerable (VU)
- 1988 – Threatened (T)
|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). |
|♦ Continuing decline in area of occupancy (AOO):||Yes|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||161000|
|♦ Continuing decline in extent of occurrence (EOO):||Unknown||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Number of Locations:||11-100||♦ Continuing 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:||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|
|♦ Number of mature individuals:||2500-9999||♦ Continuing decline of mature individuals:||Yes|
|♦ Extreme fluctuations:||No||♦ Population severely fragmented:||No|
|♦ No. of subpopulations:||1||♦ Continuing decline in subpopulations:||Unknown|
|♦ Extreme fluctuations in subpopulations:||No||♦ All individuals in one subpopulation:||Yes|
|♦ No. of individuals in largest subpopulation:||100|