Cuckoos lay their eggs in the nests of other species including dunnocks, reed warblers and meadow pipits.
The habitat is already attracting birds such as sedge and reed warblers, cuckoo, snipe, woodcock and oystercatcher.
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Over the course of six years, they watched 472 nests in which warblers had laid their eggs.
It also means that parent warblers do not have to count their young.
But turtle doves, yellow wagtails and reed warblers may expand their ranges.
Warblers whose nests were thus protected did well, raising an average of four chicks to maturity in the absence of a cowbird parasite.
These include mute swans, little grebes, redshanks, sedge warblers and whitethroats.
If warblers lose a clutch, they will often produce a second.
According to the RSPB, around 650 Cetti's warblers are thought to be resident in the UK, with the majority nesting along the south coasts of England and Wales.
The team has already collected feathers from a range of surrogate species around Lake Chad in Nigeria, and is looking for further sites where warblers may be wintering.
At the same time, they reduced the diameter of the entrances to some of the nest boxes, in order to deny admission to cowbirds (which are larger than warblers).
Christa Mateman, at the Netherlands Institute of Ecology, in Heteren, and Jan Komdeur, at the University of Groningen, and their colleagues, have discovered that young female Seychelles warblers sometimes help at their parents' nest for a year or two after they hatch.
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