Wood Warbler
Close up of a perched Wood warbler
Wood warbler in its natural habitat
Wood warbler flying low over a pond
Phylloscopus sibilatrix
Wood warblers are tuneful breeding visitors, arriving in British woodlands from April onwards. Well hidden in their preferred tree-filled landscapes, their bright yellow breast makes them easily distinguishable from other similar warbler species.
Wood Warbler
Close up of a perched Wood warbler
Wood warbler in its natural habitat
Wood warbler flying low over a pond
Length:
12cm to 13cm
Wingspan:
19.5cm to 24cm
Weight:
8g to 12g
Wood warblers display the typical colouring shared by other leaf warblers, including the chiffchaff, willow warbler and Bonelli’s warbler, with green upper parts and white underparts.
A distinguishing feature of the wood warbler is its lemon-yellow upper breast, yellow stripe above the eye and yellow throat. It has a long tail and its wings are long and pointed.
Female and male wood warblers are alike in size and plumage.
Juvenile wood warblers have a greyish tinge to their upper parts. Their plumage is more washed out than that of adult birds, and the yellow colouring on their throats and breasts is not as clear or extensive as that seen in adults of the species.
Close up of a perched Wood warbler
There is no difference in size between male and female wood warblers. Adults are roughly the same size as robins or goldfinches. The average measurement range for the species is:
Close up of a Wood warbler
Wood warblers have two song types: a high-pitched metallic flowing trill of notes, likened to the sound made by a coin spinning on a tabletop, and a rapid series of descending lower pitch notes. Contact calls heard in aggression or nest defence include a harsh ‘pip’ or ‘sip’ sound.
Wood warblers are primarily insectivorous, but later in the year, some fruit may be taken. Flying insects, including mayflies, sawflies, damselflies and lacewings, are frequently caught by the sallying technique of pursuing prey and catching them midflight.
Smaller bugs, larvae, spiders, earwigs and beetles are taken from leaves and tree trunks, as well as from undergrowth.
Fruits that form part of a wood warbler’s late summer diet include buckthorn, plum, elder, bramble and bilberry.
Young wood warblers are mainly fed on caterpillars and larvae initially, with flies gradually being introduced as they prepare to fend for themselves.
Wood warblers are primarily insectivorous
Deciduous woodland with little low-level shrubbery are the most common habitat sought by wood warblers. Beech, oak, hornbeam and sweet chestnut are all popular choices for nesting and foraging.The species prefers closed canopy without clearings, and across Europe, lowland forests are the chief habitat.
In the UK, breeding wood warblers are mainly found in oak woodlands in uplands to the west of the country, which characteristically benefit from a mild, wet Atlantic climate.
Wood warblers breed from the British Isles and western Norway in the west across northern Europe to south-central Siberia in the east.
In the south, the south of France, southern Italy, northern Greece, and north-west Turkey form the extremes of the species’ range, and breeding occasionally takes place further west, into Kazakhstan and the Caucasus region.
Winters are spent south of the Sahara from Senegal in the west, across to South Sudan, and are fairly common winter residents in forests in the Democratic Republic of Congo, Uganda, Rwanda, Kenya and Somalia.
Wood warblers are usually found in deciduous woodlands
Within Europe, Germany, Estonia, and Latvia have the most stable populations of wood warblers, while in Belarus and Russia the species is prevalent, with estimates of up to 100 million pairs in Russia.
In the UK, wood warblers are considered a rare summer visitor, with an estimated 6,500 males arriving to breed each year. This number has fallen dramatically since the 1980s, when annual estimates stood at 17,200 males.
Due to their unobtrusive nature of blending into their woodland surroundings, Wood warblers are fairly hard to spot, making sightings quite rare.
The highest concentrations of wood warblers in Britain are found in oak woodlands of western Wales. The Scottish borders and parts of northern England also welcome visiting breeding wood warblers each spring.
In Ireland, a small but well-established breeding ground can be found in County Wicklow, on the east coast.
Wood warbler singing on a branch
The oldest recorded wood warbler reached 6 years and 11 months. A typical lifespan is much shorter, between 1 and 4 years, with first time breeding in their first year
Avian predators include jays, sparrowhawks and buzzards. Mammals that prey on wood warblers and their nests include pine martens, badgers and foxes.
Wood warblers are a species protected by the Wildlife and Countryside Act, 1981, which states that it is against the law to knowingly kill, injure or take one into captivity.
Wood warbler numbers have fallen significantly in Britain, leading to their classification initially as an Amber status species on the UK Birds of Conservation Concern list in 2002, before being reassessed as a higher risk Red status bird in 2009.
Once relatively common in lowland England, the species is now considered rare in most of the country and breeding is mainly restricted to parts of Wales and regions along the England-Scotland border.
Front on view of a Wood warbler
While trees are used for foraging, nest sites established by willow warblers are usually at a much lower level, for example concealed in ground-level vegetation, or against a grassy tussock or a fallen tree.
Nests are dome-shaped, and built from dry grasses, bark, leaves, stems and animal fur, with nest construction undertaken by the female over a period of 3 to 4 days.
Wood warblers lay between 5 and 7 highly speckled glossy white eggs, measuring around 16 mm by 13 mm (0.6 in by 0.5 in). Eggs are laid in late May, with females alone incubating the clutch for 12 to 13 days.
Most wood warbler pairs remain together for the duration of one breeding season, typically raising one brood together. In subsequent years, a different mate will be chosen. Some extra-pair copulation occasionally does occur.
Wood warbler nest with young chicks inside
Vocal aggression may be shown between rival males, or when a threat is sensed near to a nest site, but otherwise wood warblers are generally relatively passive and tolerant of other species on the same territory.
While wood warblers usually forage alone or in pairs, small groups may be seen together in winter with 3 or 4 birds. Migration flocks of up to 15 birds, sometimes mixed-species flocks, may form in passage.
Little is known about overnight roosting habits of wood warblers. They are thought to head to the upper canopy of woodland to rest each night, where they are sheltered and protected from ground predators.
Wood warbler singing from a branch in the spring
Wood warblers are a fully migrational species, breeding across northern, central and southern Europe, before heading across the Mediterranean and northern Africa to spend winters in forested territories south of the Sahara desert.
Wood warblers come to the UK to breed, but leave each autumn to return to their wintering grounds in sub-Saharan Africa.
No wood warblers remain in Britain during the winter, instead heading for humid evergreen forests, mangroves and wooded savannahs once the British weather starts to become less appealing.
First winter Wood warbler
Wood warblers are not frequent visitors to residential areas or urban settings, and seek wooded environments for nesting that offer a rich and diverse range of insects to provide them with foraging opportunities.
On the rarest of occasions, migrating wood warblers may be tempted to take a brief stopover in landscapes with native trees and a variety of insect-attracting flowering plants, such as redtwig dogwood, hibiscus, raspberry, goldenrod and pussy willow.
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