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Willow warbler migration Phylloscopus trochilus
ⶠFollow the willow warbler across the big globe
Press ⶠto play the year. Line: a simplified typical route, joining the main cluster of GBIF records in each month (adjusted for observer effort).
| Scientific name | Phylloscopus trochilus |
|---|---|
| Wingspan | 19 cm |
| IUCN status | Least concern |
| Records mapped | 3,336,012 (GBIF) |
| GPS / geolocator tracks | none with an open licence yet |
Facts from Wikidata Q27239 (CC0).
When does the willow warbler arrive in the UK?
A summer visitor in the records: sightings rise sharply from late March, are near their peak by early April, and fall away after mid September.
Bars: this speciesâ share of all UK bird records in GBIF (CC0/CC BY), by month, scaled to the peak month. Based on 219,894 UK records. Weekly counts from the GBIF occurrence search API (country=GB). Dates are read from records, not from a survey, so treat them as a guide.
When do they arrive in and leave the UK? â
Migration in the data
3,336,012 GBIF records (CC0 and CC BY 4.0 licences only) are mapped here, in 1.41° grid cells, month by month.
In Europe and Africa, the centre of the records (adjusted for observer effort) is furthest north in June (about 61°N) and furthest south in January (about 11°S).
More than half of the effort-adjusted signal there is south of the Equator in: January, February, November, December.
Month by month: centre of records in Europe and Africa
| Month | Centre (latitude) | South of the Equator |
|---|---|---|
| January | 11°S | 70% |
| February | 10°S | 72% |
| March | 14°N | 37% |
| April | 42°N | 4% |
| May | 53°N | 2% |
| June | 61°N | 0% |
| July | 61°N | 0% |
| August | 56°N | 0% |
| September | 46°N | 1% |
| October | 29°N | 17% |
| November | 4°S | 62% |
| December | 11°S | 72% |
Tracked birds
No openly licensed (CC0 / CC BY) tracking data package for this species was found in the Movebank Data Repository yet, so only records are shown.
About the willow warbler
The willow warbler is a very common and widespread leaf warbler which breeds throughout northern and temperate Europe and the Palearctic, from Ireland east to the Anadyr River basin in eastern Siberia. It is strongly migratory, with almost all of the population wintering in sub-Saharan Africa.
From the Wikipedia article âWillow warblerâ (revision 1361144628), CC BY-SA 4.0.
Sources
GBIF occurrence records, licence CC0 1.0 or CC BY 4.0 only, observations only (no specimens), filtered with: taxonKey=2493052&license=CC0_1_0&license=CC_BY_4_0&occurrenceStatus=PRESENT&hasGeospatialIssue=false&basisOfRecord=HUMAN_OBSERVATION&basisOfRecord=MACHINE_OBSERVATION&basisOfRecord=OBSERVATION. Monthly queries: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec. GBIF.org (23 October 2026) occurrence data accessed via the GBIF API; a GBIF download DOI is still to be added. Contributing datasets.