Grasshopper Warbler
Grasshopper Warbler resting on a branch
Close up portrait of a Grasshopper Warbler
Grasshopper Warbler taking off for flight
Locustella naevia
A well-camouflaged visitor to grasslands and reedbeds, grasshopper warblers arrive in Britain to breed each spring. You may stand a better chance of hearing one than actually getting a sighting, as their secretive nature of creeping through vegetation makes them almost impossible to spot.
Grasshopper Warbler
Grasshopper Warbler resting on a branch
Close up portrait of a Grasshopper Warbler
Grasshopper Warbler taking off for flight
Scientific name:
Locustella naevia
Other names:
Common Grasshopper Warbler
Family:
WarblersConservation status:
Red
Length:
12.5cm to 13.5cm
Wingspan:
15cm to 19cm
Weight:
11g to 16g
Grasshopper warblers are rather indistinctive medium-sized brown warblers. Their lack of notable markings serves them well, allowing them to remain hidden in undergrowth, and to skulk in reedbeds without being detected.
As is usually the case for warblers, there is no difference in appearance between males and females. Adult grasshopper warblers are olive-brown, streaked with darker brown.
Their underparts are creamy-brown and mottled with dark spotting on parts of the breast and flanks. Their reddish brown tail is streaked with darker grey-brown markings. They have a faint lighter eye stripe, and the rest of their face is mostly pale grey.
Young grasshopper warblers resemble adults, but their underparts are slightly more yellow.
Grasshopper Warbler singing from a perch
As well as looking identical, male and female grasshopper warblers are the same size and weight. They are considered medium members of the warbler family, and are roughly the same size as robins and goldfinches, and slightly smaller than house sparrows.
Grasshopper Warblers are a highly vocal species with an extremely distinctive call
The grasshopper warbler’s distinctive call sounds almost cicada-like, with a rapid-fire of trilled monotone clicks.
The diet of grasshopper warblers is chiefly insect-based, consisting mainly of flies, moths, beetles, aphids, dragonflies and mayflies and their larvae. Spiders, woodlice, and small molluscs are also eaten.
Grasshopper warblers forage on the ground, sifting through vegetation and finding tiny insects on the foliage.
Grasshopper warbler young are fed aphids, green caterpillars, woodlice and flies by both parents.
Grasshopper Warblers mainly feed on insects, which they forage for on the ground
During the breeding season, grasshopper warblers head for scrublands, sedge, reedbeds and marshes. They are also attracted by the cover offered by bramble and nettle beds, moorlands, and the fringes of grazing fields.
Wintering habitats include bushy grasslands, woodland undergrowth, low-lying floodland, rice fields and scrubland.
Grasshopper warblers breed across Europe, from Britain and Ireland, southern Scandinavia and Finland in the north, as far south as the Alps, northern Spain and Portugal. To the east, the range extends across eastern Europe into Russia, reaching north-west China and much of central Asia.
Less is known about the wintering grounds of the grasshopper warbler, but the species is confirmed in isolated patches of West Africa, including Senegal, Mali, Sierra Leone and Ghana, as well as parts of Ethiopia and India.
There are no resident populations of grasshopper warblers anywhere in the world. Breeding and wintering are always in two distinct locations thousands of miles apart.
Lowland landscapes are preferred for both breeding and wintering, with altitudes of up to 500 m preferred across most of Europe.
In the UK, grasshopper warblers’ breeding grounds are scattered across the country, and they are observed to avoid upland areas and large settlements.
Grasshopper Warblers are most commonly spotted in scrubland, reedbeds and marshes.
There are around 12,000 breeding pairs of grasshopper warblers in the UK, so they are not the most common bird you’ll see, but their numbers are considered stable. Outside of the breeding season, there’s close to zero chance of spotting one.
Grasshopper warblers that breed in the UK leave for their winter territories during August. Birds seen in September and October are usually migrants in passage from breeding grounds in Scandinavia. Between late October and the end of March, sightings are practically non-existent.
Grasshopper warblers have been dubbed the ‘most inconspicuous bird in the Western Palearctic’, and its fondness for skulking out of sight in dense waterside vegetation makes it hard to spot, even in the right locations.
With a huge amount of patience, you may get lucky waiting it out in scrubland or marshland environments throughout England, Wales and southern Scotland, by listening out for the distinctive grasshopper-like call.
Common Grasshopper Warbler perched on a reed
Around 2 years is thought to be a typical lifespan for grasshopper warblers, although a ringed individual, discovered in 1986, was recorded to have reached 5 years.
The clever distracting call of a grasshopper warbler acts as a deterrent to many predators, who are tricked into thinking that it is an insect rather than a bird that they are hearing. Nest predators may include rats and weasels.
As a bird that breeds in Britain, grasshopper warblers enjoy protection offered by the Wildlife and Countryside Act, 1981, which legislates against them being hunted, killed, injured or captured. The Act also prevents their nests and eggs being deliberately destroyed or damaged.
Declines in grasshopper warbler numbers were noted between the 1960s and 1980s, due to habitat loss and degradation in both wintering and breeding grounds used by the species.
Grasshopper warblers are on the UK’s Red List of Birds of Conservation Concern. However, there are signs that things are looking up for these undergrowth hide-and-seek champions, with the BTO stating a 23% rise between 1985 and 2009, declaring that grasshopper numbers are now stable.
In the UK, Grasshopper Warbler numbers are thought to becoming stable
Nest-building is a joint effort for grasshopper warblers, with males and females both involved in gathering materials and nest construction.
Nests are built on or close to the ground, concealed in dense vegetation, such as deep into brambles or sedge, reedbeds, gorse bushes or among grassy tussocks.
Nest materials, including grasses, sedge and mosses, are woven into a well-defined cup shape, and lined with finer grasses and plant parts.
Grasshopper warbler eggs are creamy white in colour and speckled with fine reddish spots or blotches. Eggs measure 18 mm by 14 mm (0.7 in by 0.6 in) and weigh about 1.7 g (0.1 oz).
A typical clutch contains 4 to 6 eggs, and incubation, which is shared between males and females, lasts for around 14 days.
Pairs of grasshopper warblers stay together for the duration of the breeding season, and most commonly raise two broods together.
Close up of a young (juvenile) Grasshopper Warbler, after recently fledgling the nest
Grasshopper warblers are observed to be solitary and territorial birds, and especially vocal when defending their nest sites.
Grasshopper warblers are migratory, and have distinct breeding and wintering grounds thousands of miles apart. Grasshopper warblers arrive to breed in the UK from April onwards, and head back to their southern wintering grounds, found in West Africa, from August.
Birds that breed further east across Europe and into Asia are also believed to migrate southwards, spending winter months at sites in Kenya and Ethiopia in East Africa, and to parts of northern and western India.
Grasshopper Warblers usually start to arrive in the UK from April
The mechanical clicking sound made by male grasshopper warblers is heard during the breeding season, particularly between April and June. Grasshopper warblers sing from dusk until dawn, but are frequently heard singing at night, particularly early in the breeding season.
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