EN
Black-billed Gull Larus bulleri



Taxonomy

Taxonomic source(s)
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.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Turbott, E.G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- A2ce+3ce+4ce A2ce+3ce+4ce

Red List history
Year Category Criteria
2016 Endangered A2ce+3ce+4ce
2012 Endangered A2ce+3ce+4ce
2008 Endangered A2c,e; A3c,e; A4c,e
2006 Endangered
2005 Endangered
2004 Vulnerable
2000 Vulnerable
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern
Species attributes

Migratory status full migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 394,000 medium
Extent of Occurrence non-breeding (km2) 512,000 medium
Number of locations 11-100 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals not applicable not applicable 0
Population trend Decreasing medium estimated -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 50-79 - - -
Decline (10 years/3 generation past and future) 50-79 - - -
Number of subpopulations 2-100 - - -
Largest subpopulations 1-89 - - -
Generation length (yrs) 11.5 - - -

Population justification: The most complete nationwide census was carried out in 1996-1997 (G. A. Taylor per R. Coumbe in litt. 2000), and counted 48,000 nests (Powlesland 1998), thus the number of mature individuals is estimated to be 96,000; however, more up-to-date survey data are required.

Trend justification: Very rapid declines have been noted in a number of this species's populations over the last couple of decades. Despite increases in numbers of a few smaller colonies, the species is believed to be undergoing a continuing and very rapid decline overall.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
New Zealand N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
New Zealand Lake Grassmere
New Zealand Mararoa River
New Zealand Aparima River
New Zealand Mataura River
New Zealand Whitestone River
New Zealand Oreti River
New Zealand Orari River
New Zealand Opihi River
New Zealand Ashburton River
New Zealand Rakaia River
New Zealand Hurunui River
New Zealand Firth of Thames
New Zealand Waiau River
New Zealand Upper Buller
New Zealand Ka Whata Tu o Rakihouia/Kaikoura
New Zealand Punakaiki
New Zealand Ahuriri River
New Zealand Ashley River Rakahuri
New Zealand Clarence Acheron Saxton Rivers
New Zealand Dart Rees Rivers
New Zealand Godley Cass Rivers
New Zealand Hunter River
New Zealand Hopkins Dobson Rivers
New Zealand Kahutara River
New Zealand Makarora
New Zealand Maketu
New Zealand Manuherikia
New Zealand Matukituki River
New Zealand Motueka River
New Zealand Ohau Pukaki Tekapo Rivers
New Zealand Manukau Harbour
New Zealand Rangitata River
New Zealand Tasman River
New Zealand Waiau River Southland
New Zealand Waimakariri River
New Zealand Wairau River
New Zealand Waitaki River
New Zealand Greenstone Caples Rivers
New Zealand Awatere River
New Zealand Lower Clutha River Mata-Au
New Zealand Eglington River
New Zealand Omaui Island Oreti Estuary
New Zealand Waipu Estuary
New Zealand Clarence River mouth
New Zealand Te Waihora
New Zealand Papakanui Spit
New Zealand Pegasus Bay Coast
New Zealand Nevis Shotover Rivers
New Zealand Mangawhai
New Zealand Kaipara Harbour
New Zealand Rotorua Sulphur Point
New Zealand Bluff Harbour Awarua Bay
New Zealand Wairarapa Moana Ruamahanga
New Zealand Farewell Spit
New Zealand Wairau Lagoons
New Zealand Cook Strait
New Zealand Kaikoura (offshore)
New Zealand Canterbury (offshore)

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Pastureland major non-breeding
Artificial/Terrestrial Urban Areas suitable non-breeding
Marine Coastal/Supratidal Sea Cliffs and Rocky Offshore Islands suitable non-breeding
Marine Intertidal Rocky Shoreline suitable non-breeding
Marine Intertidal Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc suitable non-breeding
Marine Intertidal Shingle and/or Pebble Shoreline and/or Beaches suitable non-breeding
Marine Neritic Estuaries suitable non-breeding
Marine Neritic Macroalgal/Kelp suitable non-breeding
Marine Neritic Seagrass (Submerged) suitable non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable non-breeding
Marine Neritic Subtidal Sandy suitable non-breeding
Marine Neritic Subtidal Sandy-Mud suitable non-breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) suitable breeding
Wetlands (inland) Permanent Freshwater Marshes/Pools (under 8ha) suitable breeding
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) major breeding
Wetlands (inland) Seasonal/Intermittent Freshwater Lakes (over 8ha) suitable breeding
Wetlands (inland) Seasonal/Intermittent Freshwater Marshes/Pools (under 8ha) suitable breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Energy production & mining Mining & quarrying Timing Scope Severity Impact
Past, Likely to Return Minority (<50%) Negligible declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Erinaceus europaeus Timing Scope Severity Impact
Future Majority (50-90%) Rapid Declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Mustela erminea Timing Scope Severity Impact
Future Majority (50-90%) Rapid Declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Mustela furo Timing Scope Severity Impact
Future Majority (50-90%) Rapid Declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Mustela nivalis Timing Scope Severity Impact
Future Majority (50-90%) Rapid Declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus norvegicus Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Trichosurus vulpecula Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Transportation & service corridors Shipping lanes Timing Scope Severity Impact
Past, Likely to Return Minority (<50%) Negligible declines Past Impact
Stresses
Ecosystem degradation

Recommended citation
BirdLife International (2020) Species factsheet: Larus bulleri. Downloaded from http://www.birdlife.org on 13/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/07/2020.