Sedge warbler. Acrocephalus schoenobaenus.

File:Sedge Warbler from the Crossley ID Guide Britain and Ireland.jpgRichard Crossley CC BY SA 3.0 license.  ID Guide to Britain and Ireland.


The sedge warbler belongs to the Acrocephalidae and the passeriformes {perching birds} and the family Sylvioidea, and placed in the genus Acrocephalus and given the species name of schoenobaenus. the genus name derives from the Greek akros meaning pointed + kephale meaning head. The specific name derives from the Greek skhoiniklos indicating a reed + baino -to walk.

Conservation status in Britain they are on the Green list of conservation concern indicating there are no current issues with the species. In Europe they are a bird of least concern as far as population numbers are concerned. Britain's estimated population in the year 2000 was 297,000. While in Europe there is an estimated 15 million birds.

The modern day distribution of the bird is that they breed across central Europe and west and central Asia. They winter in tropical Africa. There are concerns, however, that loss of wetland areas were they fuel up for migration and the expansion of the Sahara desert are deemed to be a threat to the sedge warblers breeding populations.

Here we look at the bird's lifestyle and breeding in Europe, with the emphasis on Britain, along with some historical references by past ornithologists. As always we commence this review with a description of the bird.

Description of the sedge warbler.

Adults in Spring--- The sexes are alike, the male perhaps being a trifle brighter and rather larger, however, it is almost impossible to differentiate them in the field.

The upper parts are of an umber brown tint shading into an almost unspotted rusty brown on the rump and upper tail coverts. There is a conspicuous buffish white superciliary { eye stripe} and an equally conspicuous blackish stripe. The feathers in the middle part of the crown have dark centres forming three longitudinal stripes. The lores { The area between the eyes and the base of bill},are blackish brown, cheeks brown and the upper parts of the ear coverts slightly more dusky, these latter forming with the lores a darkish stripe through the eyes.

 The hinder part of the neck is almost unspotted, whereas the back an shoulders have each feather with a blackish brown center forming about six stripes on the back. The wing coverts are blackish brown with umber edges.to each feather, the flight feathers are brown with slightly lighter edges, the innermost secondaries having blackish brown centers and light umber brown edges, the primaries having narrow whitish brown tips.

The upper part of the tail is dark umber brown with lighter edges of the same tint, both colours gelling lighter towards the outermost rectrices { any of the large stiff feathers of a the tail which are used to control direction in flight.} The throat is whitish, the crop and sides of the neck buff shading into umber buff on the flanks and under tail coverts. Abdomen whitish, and the under part of the tail greyish brown with a wash of lavender grey.

The upper mandible is dark horn lavender, the lower mandible light lavender flesh, darker towards the tips and the corner and inside of the mouth is orange yellow. The irides are dark brown. The legs are an olive buff and the toes and claws are olive grey.

In relation to their body size the wings are medium short the tail medium length the neck short, bill short and the legs are medium length. They are 13 cm in length with a wing span of 19 cm the male and female adults weigh 129 grams.

Movement--Flitting action in flight but rarely flies far. Skulks about in reeds. it has a special song flight.

In the field.--Can be told by broad, buff,  eye stripe, from all warblers except the rare aquatic warbler. Streaked upper-parts, with unstreaked  rufous rump also distinguish the sedge warbler from all other breeding warblers except Grasshopper warbler which has a graduated tail.

Sedge warblers are hard to observe. they keep to tall rushes and sedges.

Image by Dal.


On arrival in Britain their presence is betrayed by their babbling song, which is an energetic but not a musical refrain.Where this song is first heard they will probably remain to breed. Water or swampy localities are required for this species, for they are rarely found breeding in dry places.

They tend to inhabit wet Osier beds where different species of sedge grow in abundance, often there are species of willowherbs present in the locality. Along the banks of rivers, streams and canals they are quite common and may also be encountered near lakes and ponds where aquatic plants such as Bulrush and tall reeds such as Arundo phragmites grow.When these reeds grow to a great height as they do in countries such as Holland and Hungary, and, where the bottom is a dry mass of roots raised above the water they can be exceedingly common.

The males when they first arrive, select a certain spot of not many square meters in extent, with a tall bush or willow conveniently situated, they also tend to choose a particular branch which, is regularly during their stay,until the young are born. Even before the females arrive he will sing from this branch, which id frequently accompanied by a pretty aerial flight. It rises almost perpendicularly for a short distance in the air, turning very quickly and returning, with wings and tail outstretched to the branch.

After a short rest they either start their song afresh, begin to preen their feathers, or go in search of food.They may be observed, as the look for flies of the genus Chironomus, on the underside of the foliage. In their quest for food they work their way down through the branches and thick herbage until they reach the ground level. here they may turn their attention to aquatic insects and their larvae or small spiders before once again returning to their favourite branch, often singing as they fly.

Thus he will while away the days waiting for the arrival of the females. The ground immediately surrounding the tree is regarded as their own. Should two or three males choose trees which are quite close to each other they will seek out their food in different directions, being very careful not to poach each others territory. If one should dare to trespass on another birds territory squabbles will occur and the intruder driven off, not only members of their own species but any other type of warbler.

 They has I have observed, drive off thrushes, while conversely they will allow other birds passage, even to the point of letting them nest in their favourite tree. Nature has some curious ways! Such powers of apparent discrimination seem very curious, could it be that some unknown connection between individual or class of individuals?

On his arrival in Britain the male sings at all hours of the day, especially in the morning, frequently at night and continues until mating is over and incubation has commenced, when to a great extent he ceases. However, he will recommence when the young have flown. {see breeding below}.

The male possesses considerable ability of mimicry, the call notes and parts of songs of other species are often introduced during its own song. They have been heard to imitate the Whitethroat, Blackbird,Chaffinch, and less frequently the tree pipit. They can at times also introduce a ventriloquist effect throwing their voice confusing the listener to where he is actually located.

In the last few weeks before they leave , generally the latter weeks of August and the first part of September , they are much quieter, rarely singing, but instead, skulking in the undergrowth, and becoming once again difficult to observe. However, as they move about one can sometimes hear their call notes to one another. This is usually the only way of detected their presence. Evidently they find enough food among the stems of the reeds and rushes during this period.

I have noticed that during very wet weather their song is not so frequent nor as vigorous, neither to they appear to be very happy themselves, but rather more inclined to mope and are considerably less active.However, when the weather turns and the sun lights up the day they return to their active best.

 Their food seems to consist entirely of insects and occasional plant morsels. During the time they are in Britain the insect life is never lacking. They search for them low down among the the roots of herbage, often hopping onto and along the ground in swampy conditions, where small worms and spiders are abundant, and since they generally, frequent swampy places, swamp loving insects form a great part of their diet.

It is not uncommon to encounter the birds hunting in the willows and small alder trees, but rarely if ever do they quest for food in tall trees. During the summer months great numbers of aphids are devoured, indeed they seem to constitute the large portion of the food supply, not only for this species, but those of many others also. An inspection of the twigs of willow species will reveal these insects clustering in large numbers.

When inhabiting swampy places where the Arundo phragmites grow, they seem to find , early in the season, a quantity of food among the fluffy seeds at the top of these reeds.


illustration of a sedge warbler.

Image courtesy of the Biodiversity Heritage Library. Public domain.Male bird with stem in beak {British Warblers 1907-14} Courtesy of the BHL

Breeding and young.

The females arrive , as a rule, about ten days after the males , however, they are much more difficult to observe as they tend to skulk in the bottom of the tallest rushes and sedge. Breeding commences as soon as the females arrive. Studies have revealed that the female demands a lot of attention from the male during this period, if he is to be her partner. A male will pursue a female with drooping wings and erected head feathers, whilst uttering a rather harsh call note. Sometimes when he is quietly pursuing her he will pick up and carry a dead leaf.

If another male approaches to closely he will drive it away with a vigorous flight. While this is ongoing the female will softly use her call note and if the chase goes on to long she will intensify her call to remind him his attention would be better spent on her.

Sometime the pair play together flying at each other with the male making scolding cries. They will sit next to each other giving the impression that they are uninterested, until the male moves up and down the branch in a sideways motion, with drooping wings and tail. All these are part of the courtship ritual.

The nest is placed low down among the thick tangled undergrowth in the fork of a willow or low in the branches of a bramble, especially when the bramble is entwined with thing growth of Juncus effusus, and is constructed as follows. The foundation is dead grass of various kinds mixed with small pieces of dead thistle. the nest proper is cup shaped, deep, made of grass for the most part, often containing fluffy seeds of willow. the cavity is then lined with fine dried grass or horsehair.

 It is the female that undertakes the larger portion of the building, flying back and forth to the Salix, carrying beak-fuls of seeds, followed closely by the male who never makes the slightest attempt to help her. However, he is always close by to her, whether this is when she is collecting seeds or during her journeys back and forth.

The eggs are incubated for about fourteen days by the female. The young are born almost naked and helpless. The parents are kept fully employed in the task of breeding food for their new family. Studies have shown that it is mainly the female that tenaciously brings in the food, while the greater part of the males time is spent keeping guard. While the female is startled she will sing a few notes of the song of the male, but never drops any of the food she is carrying.

Every time she takes food into her young, she removes the droppings produced by her young, as she leaves. these are usually carried thirty yards or so away from the nest before she drops them. The young, especially during their period in the nest, are fed, largely on insects, but sometimes the caterpillars of certain butterflies and moths are taken.

 The young fledge in about a further 14 days from when they hatched out of their shell.However, until they get full command of flight they keep well concealed among the bushes and undergrowth. At this time each are fed in turn by their parents. Now and again they take the trouble to glean their own food from the leaves. The young will eventually gain the experience necessary to feed themselves and will become independent. At this stage the job of the parents is done and they will begin to wander, they can even be heard singing from the middle of cornfields. They will fuel up on any available insects until it is time to leave for their wintering grounds, and we must once again wait until next spring, before we have the company of these delightful birds once more.

Immature birds. Courtesy of the Biodiversity Heritage Library.

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