Alert Status:
Not Assessed
Estimated number of UK breeding
Population size: Unknown in the UK.
Listen to Icterine Warbler song:
Icterine Warblers look very similar to Willow Warblers, but they are larger and more robust. Their backs are grey/green while their underparts are a pale yellow with the throat becoming a pale buff colour. They have large heads with grey/green crests, where the feathers often stand slightly upright, and a pale yellow eyebrow stripe (or supercilium).
Average Length: 13 cm
Average Lifespan: 2 years
Average Wingspan: 22 cm
The diet mostly consists of invertebrates but they will supplement their diet in the summer with fruits and berries. They may be attracted to gardens by berry bushes and fruit trees as well as a healthy population of invertebrates.
While there have been breeding pairs recorded in the UK, usually in the Scottish Highlands, we know very little about how they breed here. Breeding begins in May and lasts until July, a strong cup-shaped nest is built in the fork of a tree and 4-5 eggs are laid in the nest. The eggs are incubated for 12-14 days until they hatch. The chicks are then fed for another 12-14 days. If the nest fails replacement broods are common, but they will usually only produce one brood per season.
There are not thought to be many significant threats to this species. In some parts of its range, it has declined due to competition with the Melodious warbler which has spread North and now overlaps with the Icterine warbler range. Climate-driven droughts in its wintering grounds may also drive declines in the future through the loss of suitable food supplies.
Report sightings of this bird during the breeding season to help track how the population is changing.
Plant berry and fruit bushes and create an insect-friendly garden to provide ample food for these birds.
Icterine Warblers are expert mimics, with one study finding that they can mimic around 42 different species.
BirdLife International (2023) Species factsheet: Hippolais icterina. Downloaded from http://datazone.birdlife.org/species/factsheet/icterine-warbler-hippolais-icterina. Accessed: 07/11/2023.
British trust for ornithology (no date) Icterine warbler | BTO - British trust for ornithology. Available at: https://www.bto.org/understanding-birds/birdfacts/icterine-warbler. Accessed: 07/11/2023.
Hollig, M. and the Rare Breeding Birds Panel (2011). Rare breeding birds in the United Kingdom in 2009. British Birds, 104(9), 476-537.
Jůzlová, Z., & Riegert, J. (2012). Vocal mimicry in the song of the icterine warbler, Hippolais icterina (Sylviidae, Passeriformes). Folia Zoologica, 61(1), 17–24. https://doi.org/10.25225/fozo.v61.i1.a4.2012
Noorden, B. (2015). Breeding biology of the Icterine Warbler Hippolais icterina in the Peel region (Southeast Netherlands). Limosa, 88, 153-163.
Riegert, J., & Jůzlová, Z. (2018). Vocal mimicry in the song of Icterine warblers (Hippolais icterina): possible functions and sources of variability. Ethology Ecology and Evolution, 30(5), 430–446. https://doi.org/10.1080/03949370.2017.1412356
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