Phylloscopus borealis
Silhouette: Jiekun He · PhyloPic
In 3 days ~30% in a week ~60%
The Arctic warbler (Phylloscopus borealis) is a widespread leaf warbler in birch or mixed birch forest near water throughout its breeding range in Fennoscandia and the northern Palearctic. It has established a foothold in North America, breeding in Alaska. This warbler is strongly migratory; the entire population winters in southeast Asia. It therefore has one of the longest migrations of any Old World insectivorous bird.
It traditionally included populations that breed in Kamchatka, the Kuril Islands and Japan, but genetic and vocal evidence strongly suggested these should be treated as separate species, and are all now considered distinct with the Kamchatka leaf warbler in Kamchatka, Hokkaido and the Kuril Islands, and the Japanese leaf warbler in Japan (except Hokkaido).
The nest is on the ground in a low shrub. Like most Old World warblers, this small passerine is insectivorous. This is a typical leaf warbler in appearance, greyish-green above and off-white below. Its single wing bar distinguishes it from most similar species except the greenish warbler, Phylloscopus trochiloides. It is larger than that species and has a heavier, dagger-like bill, with a dark tip to the lower mandible. Its song is a fast trill.
This species occurs as an autumn vagrant in western Europe and is annual on Great Britain. There were 225 confirmed arctic warbler sightings in Britain between 1958 and 2001. The genus name Phylloscopus is from Ancient Greek phullon, "leaf", and skopos, "seeker" (from skopeo, "to watch"). The specific borealis is from Latin and means "northern". Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Khao Luang National Park | 🇹🇭 Thailand | |
| 2 | Khao Sok National Park | 🇹🇭 Thailand | |
| 3 | Denali National Park | 🇺🇸 United States | |
| 4 | Way Kambas National Park | 🇮🇩 Indonesia | |
| 5 | Danum Valley Conservation Area | 🇲🇾 Malaysia | |
| 6 | Gobi Gurvansaikhan National Park | 🇲🇳 Mongolia | |
| 7 | Gunung Leuser National Park | 🇮🇩 Indonesia | |
| 8 | Taman Negara National Park | 🇲🇾 Malaysia | |
| 9 | Khao Yai National Park | 🇹🇭 Thailand | |
| 10 | Kerinci Seblat National Park | 🇮🇩 Indonesia | |
| 11 | Kaeng Krachan National Park | 🇹🇭 Thailand | |
| 12 | Cuc Phuong National Park | 🇻🇳 Vietnam | |
| 13 | Cat Tien National Park | 🇻🇳 Vietnam | |
| 14 | Taroko National Park | 🇹🇼 Taiwan | |
| 15 | Sepilok | 🇲🇾 Malaysia | |
| 16 | Bali Barat National Park | 🇮🇩 Indonesia | |
| 17 | Kinabalu Park | 🇲🇾 Malaysia | |
| 18 | Doi Inthanon National Park | 🇹🇭 Thailand |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Kaohsiung | 🇹🇼 Taiwan | |
| 2 | Singapore | 🇸🇬 Singapore | |
| 3 | Ningbo | 🇨🇳 China | |
| 4 | Manila | 🇵🇭 Philippines | |
| 5 | Taipei | 🇹🇼 Taiwan | |
| 6 | Kuala Lumpur | 🇲🇾 Malaysia | |
| 7 | Jinan | 🇨🇳 China | |
| 8 | Davao City | 🇵🇭 Philippines | |
| 9 | Taichung | 🇹🇼 Taiwan | |
| 10 | Novosibirsk | 🇷🇺 Russia |
With luck
About 10% of wildlife watchers report an Arctic Warbler sighting in Khao Luang National Park on a given day, based on 79 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 101st most-seen of the 215 birds we can rate there. Over three days the chance rises to about 30%, and over a week to about 60%, if each day is a fresh chance.
October and December
In those months about 30% of wildlife watchers report an Arctic Warbler in Khao Luang National Park on a given day, against under 5% in May to August, the lowest months. Those are among Khao Luang National Park's wettest months, with about 300 mm of rain a month against 65 mm in March.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Arctic Warbler sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 18 parks where we can rate Arctic Warbler sightings, Khao Luang National Park has the highest daily chance: about 10%. Next come Khao Sok National Park (Thailand, about 10%) and Denali National Park (United States, about 10%).
Same genus: Phylloscopus
The closest relatives of the Arctic Warbler that you can see in Khao Luang National Park (genus Phylloscopus, Leaf Warblers) are Eastern Crowned-Warbler (about 10%), Yellow-browed Warbler (about 10%) and Sakhalin Leaf-Warbler (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Arctic Warbler is recorded against all the birds logged in Khao Luang National Park (79 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
