Arctic Warbler Phylloscopus borealis


Taxonomic note
Phylloscopus borealis , P. examinandus and P. xanthodryas (del Hoyo and Collar 2016) were previously lumped as P. borealis following AERC TAC (2003), AOU (1998 & supplements), Christidis & Boles (2008), Cramp et al. (1977-1994), Sibley & Monroe (1990, 1993) and Stotz et al. (1996).

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2016 Least Concern
Species attributes

Migratory status full migrant Forest dependency low
Land-mass type Average mass 11 g

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 22,600,000 medium
Extent of Occurrence non-breeding (km2) 8,280,000 medium
Severely fragmented? no -
Population and trend
Value Data quality Derivation Year of estimate
Number of mature individuals 10000000-500000000 medium estimated 2015
Population trend increasing suspected -
Generation length (years) 3.6 - - -

Population justification: In Europe, the breeding population is estimated to number 3,700,000-7,000,000 pairs, which equates to 7,400,000-14,000,000 mature individuals (BirdLife International 2015). It is likely that the global population falls into the range 10,000,000-500,000,000 mature individuals.

Trend justification: The population is suspected to be stable in the absence of evidence for any declines or substantial threats. The European population is estimated to be increasing (BirdLife International 2015).

Country/territory distribution
Country/Territory Presence Origin Resident Breeding Non-breeding Passage
Brunei extant native yes
Bulgaria extant vagrant
Cambodia extant native yes
China (mainland) extant native yes
Denmark extant vagrant
Faroe Islands (to Denmark) extant vagrant
Finland extant native yes
France extant vagrant
Germany extant vagrant
Gibraltar (to UK) extant vagrant
Greece extant vagrant
Hong Kong (China) extant native yes
India extant vagrant
Indonesia extant native yes
Ireland extant vagrant
Italy extant vagrant
Kazakhstan extant vagrant
Laos extant native yes
Luxembourg extant vagrant
Malaysia extant native yes
Malta extant vagrant
Mongolia extant native yes
Myanmar extant native yes
Netherlands extant vagrant
Norway extant native yes
Oman extant vagrant
Poland extant vagrant
Russia extant native yes
Russia (Central Asian) extant native yes
Russia (European) extant native yes
Saudi Arabia extant vagrant
Singapore extant native yes
Spain extant vagrant
Sweden extant native yes
Taiwan, China extant native yes
Tajikistan extant native yes
Thailand extant native yes
Timor-Leste extant native yes yes
United Kingdom extant vagrant
USA extant native yes
Vietnam extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Sweden Sjaunja
Russia (European) Lapland Biosphere Reserve
Russia (European) Yamantau mountain
Russia (European) Verkhnevisherski mountain
Russia (European) Kumikushski wetland
Russia (European) Adovo-Chugrumski wetland
Russia (European) Iremel'ski mountain
Russia (European) Yugyd Va
Russia (European) Valley of Sysola river
Finland Talaskangas
Finland Oulanka-Sukerijärvi
Finland Elimyssalo
Finland Kemihaara (Vuotos) mires and forests
Finland Luosto
Finland Värriö-Tuntsa
Finland Saariselkä and Koilliskaira
Finland Lemmenjoki-Hammastunturi-Pulju
Russia (European) Druzhinnoe lake and its outskirts
Russia (Central Asian) Flood-plain of the Tuy river
Russia (Central Asian) Molebny Kamen' ridge
Russia (Central Asian) Poyasovy Kamen' ridge
Russia (Central Asian) Bystroistokskaya
Russia (Central Asian) Kileinoye bog
Russia (Central Asian) Kondinskiye lakes
Russia (Central Asian) Ust'-Ozerninskiye bogs
Russia (Central Asian) Vizhay river
Russia (Central Asian) Kataiginskiye bogs
Russia (Central Asian) Vodorazdel'naya
Russia (Central Asian) Dvuob'ye
Russia (Central Asian) Basins of the Schuchya and Khadytayakha rivers
Russia (Central Asian) Zapovednik "Denezhkin Kamen'"
Russia (Central Asian) East slope of the Northern Ural
Russia (Central Asian) Seketovo, Rakhtovo and Artevo lakes
Norway Øvre Pasvik
Norway Øvre Anárjohka
Norway Reisa

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Arable Land suitable non-breeding
Artificial/Terrestrial Plantations suitable non-breeding
Artificial/Terrestrial Rural Gardens suitable non-breeding
Artificial/Terrestrial Subtropical/Tropical Heavily Degraded Former Forest suitable non-breeding
Forest Boreal suitable breeding
Forest Subtropical/Tropical Dry suitable non-breeding
Forest Subtropical/Tropical Mangrove Vegetation Above High Tide Level suitable non-breeding
Forest Subtropical/Tropical Moist Lowland suitable non-breeding
Shrubland Boreal major breeding
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) suitable non-breeding
Altitude 0 - 2500 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Indirect ecosystem effects, Ecosystem degradation

Purpose Primary form used Life stage used Source Scale Level Timing
Pets/display animals, horticulture - - non-trivial recent

Recommended citation
BirdLife International (2023) Species factsheet: Phylloscopus borealis. Downloaded from on 28/09/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from on 28/09/2023.