Sylvia borin
Garden warblers are unobtrusive, inconspicuous songbirds that are most commonly found foraging in woodlands during spring and summer months, before heading south to wintering grounds in Africa each autumn.
A garden warbler’s plumage does not have any particularly distinguishing features or markings. Upper parts are grey-brown, with a greyer head, a light grey neck patch, and slightly darker wings. The breast and belly are paler grey, sometimes with a buff tinge on the flanks and neck.
The bill is short and stubby, and the legs are grey. There is a faint pale ring around the black eye, and their head is rounded.
Females and males are alike in colouring and size and there are no seasonal plumage changes during the year.
Young garden warblers are also similar to adults, making it difficult to determine the age of an individual bird on sight alone.
Garden Warbler perching on a branch
A medium-sized warbler, the garden warbler’s rounded head gives it a somewhat thick-set appearance, making it seem chunkier than other similar bird species. Males and females are the same size, falling within the ranges below:
Garden Warbler perched on a broken branch
What they lack in distinctive visual appearance, garden warblers more than compensate in musical ability. Their song is tuneful and bubbling, similar to the flowing notes of a blackcap but lower in pitch. Some mimicry also occurs. Their call is a harsh ‘chek-chek’, heard in alarm or when a threat to the nest is detected.
Garden Warbler in song
Spiders, insects, and fruit are the main foods in a garden warbler’s diet, with aphids, flies, beetles and caterpillars being of key importance during the breeding season.
Fruit, particularly figs, blackberries, buckthorn, and mulberry, form a major part of their diet later in the summer.
Small insects, larvae, and spiders are fed to garden warbler chicks by both parents.
Garden Warbler with its beak full of insects
Deciduous or mixed woodland are favourite habitats on garden warblers’ breeding grounds. A layer of dense vegetation with shrubs and thickets to forage for insects in are required to support their feeding needs.
In winter, woodlands, forest edges, parks, gardens, and orchards are preferred. Coniferous forests are usually avoided, and lower altitudes are favoured.
Garden warblers have a wide distribution range, with breeding territories stretching across northern Europe from the British Isles in the west as far east as eastern Siberia. Northern Italy and northern Spain form the lower limit of their range during the breeding season, and populations can also be found in northern Turkey.
Migration occurs each autumn to wintering grounds in sub-Saharan Africa, as far south as northern Namibia and parts of South Africa.
Europe is home to around 80 percent of the world’s garden warblers, with the highest concentrations in Switzerland and Poland.
Garden warblers may be difficult to spot, because of their non-distinctive plumage and habit of foraging out of sight in woodland vegetation. However, they are among the most common warblers, with a global population of between 41.6 and 67.3 million mature individuals, of which around 80 percent (33.3 to 53.8 million) breed in Europe.
Around 145,000 pairs of garden warblers breed in the UK each year, and although they are not the most commonly spotted summer species, their song is heard throughout British woodlands in spring and summer.
Garden warblers are common throughout England, Wales, and southern Scotland, and the best chances of a sighting are in wooded landscapes, and foraging below hedgerows on agricultural land.
Garden Warbler in natural habitat
The expected lifespan of a garden warbler is around 2 years, although ringing records show that older individuals have survived as long as 10 years and 1 month. Breeding occurs for the first time in one-year-old birds.
Sparrowhawks, falcons, and domestic cats are among the chief threats to garden warblers. Nests are commonly preyed on by jays, crows, and weasels. Their nests are also frequently targeted by cuckoos, who remove the garden warbler’s own eggs and lay their own in their place.
The Wildlife and Countryside Act, 1981, protects garden warblers against being killed, injured, or taken into captivity.
Garden warblers are widespread and abundant, and are classed as a species of least concern globally. In the UK they have Green status on the British Birds of Conservation Concern list, and the population is considered stable.
Garden Warbler perching on a honey locust branch
Garden warblers choose well-hidden nesting spots, concealed out of sight in low shrubbery or brambles. Nests are cup-shaped and made from grass, leaves, and twigs, and lined with feathers and animal hair.
The nesting season for garden warblers lasts from May to July, with pairs usually raising one brood together. Incubation is shared between the sexes and eggs hatch after 10 to 12 days. Hatchlings remain in the nest until they are 11 or 12 days old when they are ready to fledge and are fully independent around 2 weeks later.
Garden warblers lay oval-shaped eggs, which measure 20 mm by 15 mm (0.8 in by 0.6 in). Eggs are smooth and glossy, and creamy white in colour, with brownish-purple spotting at one end. Between 4 and 5 eggs is most common.
Pairs formed between garden warblers last for the duration of a single breeding season, after which the bond dissolves and a new mate is found the following year.
Nest of a Garden Warbler with five eggs
Garden Warbler adult at nest with young
Garden warblers are a relatively shy and inconspicuous species, and are not naturally aggressive. Nest territories are defended during the breeding season by vocal males, but confrontations rarely become physical.
Garden Warbler foraging on mossy ground
Garden warblers are mostly migratory, leaving their European and Asian breeding grounds in August or September and heading to Africa for winter. They return north the following spring, arriving on breeding grounds in early May. Some populations that breed in North Africa and around the Mediterranean are resident and remain in the same territories all year round.
Although around 165,000 pairs of garden warblers breed in the UK each year, none remain in the country all year round, with the entire breeding population heading to sub-Saharan Africa for winter.
Length:
14cm
Wingspan:
20cm to 24.5cm
Weight:
16g to 22g
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