Wood warbler

Habitat

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 main nest predators of wood warblers breeding in the primeval habitat of Białowieża Forest, Poland, are mammals, especially medium-sized carnivores, which mostly predate nests at night using sound or olfaction. Therefore, nest survival declined with nest progression likely due to increased predator detection of older and louder chicks.

Description

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 rare in Ireland, where there is a very small but apparently stable breeding population 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. There is also a preference for forest in the non-breeding season, however this habitat is declining in wintering areas such as Ghana. Despite the decline in forest habitats, there has been no change in number of wood warblers as it appears that this species can use degraded habitats, such as well-wooded farms. However, further loss of trees will likely have a negative impact on this species in the future.

Songs

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 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".