Grasshopper warbler

The grasshopper warbler (Locustella naevia) is a warbler, not a grasshopper! It takes its name from its distinctive cricket-like song, which might be all one notices of this particularly reclusive and well-camouflaged bird.

It is a summer visitor to Europe, spending the winter months in north Africa or southwestern Asia. In the United Kingdom it can be found in England, Wales and southern Scotland, its preferred habitat being dense shrubbery, thick grass, marshy meadows and thickets close to lakes, ponds and river backwaters.  

The grasshopper warbler is a red list species in the United Kingdom, due to its sharp drop in numbers in recent years.

Appearance

The grasshopper warbler is 12-13 centimetres (5 inches) in length. It has streaky yellow-brown or olive-brown plumage above and buff-white below with fewer streaks. It has a fairly broad rounded tail which it cocks when alighting. Male and female grasshopper warblers are very similar in appearance.

Behaviour

It is a skulking, secretive bird that spends much of its time on the ground, except when male birds perch on a stem to sing. When on the ground it could be mistaken for a mouse as it creeps through the foliage.

The grasshopper warbler’s song is a high-pitched trill that is very insect-like, and it has also been likened to a fishing reel being wound in. The bird has the ability to “throw” its voice as it sings by turning its head as it does so. This makes it something of a ventriloquist among birds. The song can go on for a full three minutes with barely a pause, and it can be heard at night as well as during the day.

Food for grasshopper warblers, whether adult or juvenile, consists of insects and small invertebrates.

Breeding

Grasshopper warblers reach their breeding grounds in late April or early May. The nest is built in May or June in a concealed place, such as a grassy tussock or dense shrub. Both partners construct the nest, which is fairly deep, from reeds or blades of grass. The clutch, of anything from four to six eggs, is incubated mainly by the female bird, for up to fourteen days. The young are fed by both parents, in the nest for around nine days and then outside the nest for a further two weeks. A second brood may be raised.

Grasshopper warblers return to their winter quarters in August or September.

© John Welford