Editing Common grasshopper warbler (section)

==Description==
[[File:2021-05-20 Locustella naevia, Rising Sun CP, Northumberland 1.webm|thumb|left|Singing bird, Northumberland, England]]
The adult is about {{convert|12.5|cm|0|abbr=on}} long, and weighs {{convert|11.5|–|16|g}}.<ref name="BTO">{{cite web | title=Grasshopper Warbler | website=BTO - British Trust for Ornithology | date=2015-04-07 | url=https://www.bto.org/understanding-birds/birdfacts/grasshopper-warbler | access-date=2025-03-25}}</ref> It is a secretive bird and can be hard to see, but its presence is easily detected because of its characteristic song.<ref name=Witherby/> The upper-parts are pale olive-brown, each feather having a central darker brown streak. The cheeks are greyish, the irises are brown and there is a faint eye streak behind the eye. The upper mandible of the beak is dark brown and the lower mandible yellowish-brown. The underparts are cream-coloured or yellowish-buff with a few dark brown spots and streaks on the breast and flanks. The wings are brown with the outer edge of the feathers rimmed with paler brown. The tail feathers are reddish-brown with faint transverse bars being visible in some individuals and the under-tail [[Covert feather|coverts]] are streaked. The slender legs and the feet are pale yellowish-brown.<ref name=Witherby>{{cite book |title=Handbook of British Birds, Volume 2: Warblers to Owls |editor-last=Witherby |editor-first=H. F. |year=1943 |publisher=H. F. and G. Witherby Ltd. |pages=36–30 }}</ref>

The song is a long, high-pitched reeling trill performed with beak held wide open and the whole body vibrating. It lasts from a few seconds to several minutes without any pauses, and is of remarkable speed and complexity, consisting of 52 notes (26 double notes) per [[second]]; its speed and high pitch however make it impossible for human ears to analyse without slowed-down recordings. It varies in volume from a sound resembling an angler's [[Fishing reel|reel]] to a distant mowing machine. It is strongly [[ventriloquism|ventriloqual]], making it difficult to pinpoint the location of the singing bird, but has strong carrying power, audible at ranges of up to 500 m to even 1 km. The song can be heard at any time of day or night, but peaks around dawn and dusk, and can be heard from the arrival of the birds in April until early August.<ref name="Snow">{{cite book | last=Snow | first=David William | title=The Birds of the Western Palaearctic | publisher=Oxford Univ. Press | publication-place=Oxford | date=1998 | isbn=0-19-854099-X | page=1245–1247}}</ref><ref>{{cite book |last1=Hansen |first1=Per Schiermacher |title=Nattergaleturen |date=1980 |publisher=Dansk Ornithologisk Forening |location=København |pages=1-8 + audio cassette |language=da}}</ref><ref>{{cite web | title=Grasshopper Warbler (Locustella naevia) | website=www.birdwords.co.uk | date=2019-09-26 | url=https://www.birdwords.co.uk/home-v/bird-factsheets/grasshopper-warbler-locustella-naevia/ | access-date=2025-03-25}}</ref> The alarm call is a repeated ticking noise that has been rendered as "twkit-twkit-twkit".<ref name=Coward>{{cite book |title=The Birds of the British Isles and their Eggs, Volume 1 (Corvidae to Sulidae) |last=Coward |first=T.A. |year=1941 |publisher=Frederick Warne |asin=B00085ZBTC |pages=169–171 }}</ref> The song shows similar 'reeling' structure to that of some of its congeners, notably [[lanceolated warbler]] (''Locustella lanceolata''), [[Savi's warbler]] (''Locustella luscinioides'') and [[river warbler]] (''Locustella fluviatilis''), though they are all distinguishable in different tones and speed.<ref>{{ cite book | last1=Svensson | first1=Lars | last2=Mullarney | first2=Killian | last3=Zetterström | first3=Dan | year=2009 | title=Collins Bird Guide | edition=2nd | location=London | publisher=HarperCollins | isbn=978-0-00-726814-6 | page=318 }}</ref>