|In Inversnaid, Scotland|
|Yellow: Breeding (summer only)
Blue: Non-breeding winter visitor
The wood warbler (Phylloscopus sibilatrix) is a common and widespread leaf warbler which breeds throughout northern and temperate Europe, and just into the extreme west of Asia in the southern Ural Mountains. The genus name Phylloscopus is from Ancient Greek phullon, "leaf", and skopos, "seeker" (from skopeo, "to watch"). The specific sibilatrix is Latin for "whistler".
This is a bird of open but shady mature woodlands, such as beech and sessile oak, with some sparse ground cover for nesting. The dome-shaped nest is built near the ground in low shrub. 6 or 7 eggs are laid in May; there may be a second brood. Like most Old World warblers, this small passerine is insectivorous.
The wood warbler is 11–12.5 cm long, and a typical leaf warbler in appearance, green above and white below with a lemon-yellow breast. It can be distinguished from similar species, like the chiffchaff P. collybita and the willow warbler, P. trochilus by its yellow supercilium, throat and upper breast, pale tertial edges, longer primary projection, and by its shorter but broader tail.
It is a summer visitor to the United Kingdom, seen from April until August. It has declined there in recent years; it is now very rare in Ireland, where only one or two pairs are recorded breeding in most years, usually in County Wicklow.
Various factors associated with forest structure, including slope, forest cover, proportion of broad-leaf forest, canopy height and forest edge length, all influenced the occupancy rates of this declining forest species. Conservation measures are therefore required that provide and maintain the wood warblers preferred forest structure. 
It has two song types, often (but not always) given alternately; a high-pitched fluid metallic trill of increasing tempo pit-pit-pitpitpitpt-t-t-ttt (help·info) lasting 2–3 seconds, and a series of 3 to 5 descending piping notes of lower pitch piüü-piüü-piüü. The contact call is a soft piping note, similar to the second song type, but shorter and given singly, "piü".
- BirdLife International (2012). "Phylloscopus sibilatrix". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 305, 355. ISBN 978-1-4081-2501-4.
- Perry, Kenneth W. "The Annual Report of the Irish Rare Birds Breeding Panel 2102" Irish Birds Vol.9 p.572
- Huber, N.; Kéry, M.; Pasinelli, G. (2017). "Occupancy dynamics of the Wood Warbler Phylloscopus sibilatrix assessed with habitat and remote sensing data". Ibis. 159 (3): 623–637. doi:10.1111/ibi.12472.