Savi’s warblers are long-distance migratory songbirds, breeding across continental Europe and north-west Africa, and spending winters in West Africa. Extremely rare in the UK, with only around 5 breeding pairs a year, Savi’s warblers are mostly found in marshlands and habitats with dense reed cover.
Savi’s warblers have a warm brownish-grey back, nape, and crown and a paler greyish-white belly, breast, throat and chin. They have a darker brown tail, which is a duller brown underneath. A Savi’s warbler’s throat is not streaked, a characteristic that allows them to be told apart from the very similar river warbler.
Male and female Savi’s warblers are identical in colouring and size. Both have pale brown to pinkish-brown legs, olive-brown irises and a horn-grey bill.
Young Savi’s warblers are also similar to mature birds but have an overall more rufous or yellow wash.
Savi's Warbler sitting on the reeds by the river
Savi’s warblers are medium-sized members of the warbler family and are around the same size as a chaffinch. There’s no difference in size between males and females in this species.
Savi's Warbler perching on a bulrush
Savi’s warblers have a distinctive, continuous insect-like reeling song, similar to that of a grasshopper warbler. The song is loud and carries over a long distance, and provides a good guide to identifying the species – perhaps more so than a visual identification, as they are notoriously elusive when it comes to sightings.
Savi's Warbler perching in the reedbed singing
The diet of a Savi’s warbler is almost exclusively insect-based, with mayflies, dragonflies, and damselflies and their larvae, grasshoppers, flies, and beetles among the leading prey. Spiders and some water snails are also eaten.
Savi’s warblers are fed by both parents, with larvae and soft insects brought to the nest.
Savi's Warbler with insects in its beak
Habitats preferred by Savi’s warblers include marshes, fens and reedbeds, next to shallow water and surrounded by rushes, sedge, and other aquatic vegetation cover.
Non-breeding habitats include marshes and swamps, as well as fields cultivated for rice and sugar cane.
The British Isles form the extreme western edge of the breeding range of Savi’s warblers. The species has a patchy distribution across northern France, Spain and Portugal, and becomes more widespread across central and eastern Europe, as far north as the Baltic states, and through Poland, Belarus, Ukraine, and into south-western Russia.
The species is widespread in Afghanistan and Kazakhstan and is also an established breeding bird in Morocco, Algeria and Tunisia.
European populations of Savi’s warblers spend winters in West Africa, from Senegal to Lake Chad and as far south as north Ghana. Some migration to South Sudan and Ethiopia also takes place, particularly from Savi’s warblers that breed further east into Turkey and central Asia.
Savi's Warbler in natural habitat
The European population of Savi’s warblers was estimated in 2015 at between 281,000 and 474,000 pairs. Europe represents around 65 percent of the world population, estimated at almost 1.5 million individuals. In Europe, Romania, Hungary, Russia and Turkey have the highest numbers of breeding Savi’s warblers.
With only around 5 pairs nesting in the UK each year, Savi’s warblers are an extremely rare breeding bird species in Britain. Sightings are scarce, due to the low numbers, but also thanks to the secretive nature of the species, which prefers to remain hidden out of sight in dense reedbed environments. Its distinctive, insect-like song is often the first clue to its presence.
With such a tiny breeding population of only 5 birds a year, sightings of Savi’s warblers in the UK are exceptionally rare. Most observations in Britain have been reported at marshy reedbeds in the south and south-east of England, in Kent, Suffolk and Norfolk.
Savi's Warbler perching in the marshy reedbeds
The average lifespan for Savi’s warblers is between two and five years. Occasionally older birds are recorded, through ringing records, including an individual that reached 9 years and 9 months. First-time breeding is thought to occur at one year of age.
Female Savi’s warblers are vulnerable to predation when brooding eggs and nestlings and eggs are frequently attacked. The main threats to both nests and adult birds are brown rats, water voles, foxes, bitterns and occasionally moorhens.
Savi’s warblers are listed as a Schedule I bird under the Wildlife and Countryside Act, 1981, legislation that protects them from being killed, injured, or taken into captivity, as well as offering additional protection for their nest sites, eggs and young from being destroyed or damaged.
Across their wider range, Savi’s warblers are classified as a species of least concern, with population numbers showing increases in parts of central and eastern Europe.
However, in much of the southern western parts of its range, the numbers of Savi’s warblers are in decline. In the UK, it is exceptionally rare, with only 5 pairs arriving to breed each year, which justifies the species’ Red status on the British Birds of Conservation Concern list.
In the Netherlands, a decline of between 50 and 75 percent of Savi’s warblers was recorded between 1965 and 1993.
Drainage of wetlands in both breeding and wintering territories used by Savi’s warblers is a key factor that has led to the decline in population. Natural changes, caused by weather and rises in water levels, can also threaten the future survival of the species.
Savi's Warbler standing on a wooden bridge by the river
Savi’s warblers build their nests in dense reedbeds, directly above water or swampy ground. Nests are concealed within reeds and other waterside vegetation, up to 50 cm (20 in) off the ground. A deep cup is constructed from stems and leaves of aquatic plants, and lined with leaves and other plant parts.
Savi’s warblers arrive on their breeding grounds from early April onwards and laying begins in late April in western and central Europe and from mid-April for populations further south, with May to June being the peak months for eggs to be laid. Incubation lasts for 10 to 12 days, by the female alone.
Savi’s warblers’ eggs are pale greyish-blue, densely marked with dark reddish-brown speckles. A typical clutch contains 2 to 6 eggs, which measure 20 mm by 14 mm (0.8 in by 0.6 in).
Savi’s warblers are monogamous for the duration of a single breeding season, raising either one or two broods together before pairs separate ahead of winter migration.
The nest of a Savi's Warbler with four eggs
Savi’s warblers are highly territorial, particularly males during the breeding season, and nest sites and mates will be defended vocally with intense bursts of song.
Savi's Warbler in song
Savi’s warblers are a fully migratory species, breeding in Europe and Central Asia, and spending winter months in West Africa and north-east Africa. No Savi’s warblers remain in Europe once the breeding season ends, departing south in late August or early September.
In the UK, Savi’s warblers are an incredibly rare breeding bird, with only up to 5 pairs raising young in Britain each year. No individuals are residents all year round, and summer arrivals are never guaranteed.
14cm to 15cm
15cm to 20cm
14.5g to 16.5g
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