Grasshopper Warbler

Listen to example recordings of the main vocalisations of Grasshopper Warbler, provided by xeno-canto contributors.

This species can be found on the following statutory and conservation listings and schedules.

UK Birds of Conservation Concern	Red listed
Species of European Conservation Concern	Least Concern
IUCN Red List of Threatened Species (global)	Least Concern
Schedule 1 license required (to disturb)	No
Birds Directive Annex 1	No
Listed on the Annexes of	Bern(III), Bonn(II), NERC (41)

Grasshopper Warbler was previously amber-listed because of a contraction in range during the period preceding the 1988-91 Atlas (Gibbons et al. 1993). The CBC index suffered from small and severely dwindling sample sizes, but the available data indicate a rapid population decline between the mid 1960s and mid 1980s, when numbers became too small for annual monitoring (Marchant et al. 1990). On this basis, the species is now red-listed. The BBS shows wide fluctuations in abundance since 1995, with no clear trend for the UK and a moderate decline in England. There has been a decline across Europe since 1980 (PECBMS: PECBMS 2020a>).

UK breeding population

No population change in UK (1995–2020)

Grasshopper Warblers are widespread throughout much of Britain with the exception of high elevations, the Outer Hebrides and Shetland. There are also gaps in parts of northern England, along the Welsh border, and in southern England. They are widespread in Ireland, except in the southeast. The highest densities are found across Ireland, especially the west, as well as in Wales and southwest Scotland.

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Occupied 10-km squares in UK

No. occupied in breeding season	1800
% occupied in breeding season	60
No. occupied in winter	1
% occupied in winter	0.03

European Distribution Map

European Breeding Bird Atlas 2

Breeding Season Habitats

Most frequent in

Reedbed

Relative frequency by habitat

Relative occurrence in different habitat types during the breeding season.

Breeding Grasshopper Warblers have been lost from a large swathe across English south-coast counties and also pockets in the east and midlands of Ireland. These substantial losses are offset by a marked gains in Scotland, especially in the northwest, and in the extreme west and southwest of Ireland.

% change in range in breeding season (1968–72 to 2008–11)

-10.6%

Grasshopper Warbler is a summer migrant, arriving in April when its reeling song enables easy detection. Birds are detected infrequently during autumn migration.

View a summary of recoveries in the Online Ringing Report.

Foreign locations of birds ringed or recovered in Britain & Ireland

View number ringed each year in the Online Ringing Report

Maximum Age from Ringing

5 years 0 months 16 days (set in 1986)

Wing Length	Adults	63.8±1.7 | Range 61–67mm, N=790
	Juveniles	64.2±1.6 | Range 62-67mm, N=2655
	Males	64.6±1.6 | Range 62–67mm, N=221
	Females	63.3±1.6 | Range 61–66mm, N=95

Body Weight	Adults	13.3±1.13 | Range 11.5–15.2g, N=725
	Juveniles	13.1±1.0894 | Range 11.5–15.0g, N=2601
	Males	13.1±0.93 | Range 11.7–14.7g, N=193
	Females	13.6±1.46 | Range 11.5–16.2g, N=85

Feather measurements and photos on featherbase

Ring size	A
Field Codes	2-letter: GH | 5-letter code: GRAWA | Euring: 12360

For information in another language (where available) click on a linked name

Causes of change

The demographic and ecological causes of population change in this species are largely unknown.

Further information on causes of change

There are not enough data to carry out demographic analyses for this species and the causes of the decline, both demographic and ecological, are largely unknown.

Although there is no specific evidence available, as this species is a migrant, it is possible that it has suffered from changes in conditions in the African Sahel zone along with some other trans-Saharan migrants.

Another hypothesis, again lacking good evidence to support or refute it, is that the decline is related to a recent decrease in the amount of suitable scrub habitat preferred by breeding Grasshopper Warblers. There are strong pointers that structural aspects of preferred habitat are important, including heterogeneity, and it seems likely that breeding habitat is limited, at least in some parts of Britain (Gilbert 2012). However, the Grasshopper Warbler's decline has been fairly steep and perhaps too rapid for gradual changes in scrub habitat availability or post-afforestation decline to be major factors (Riddiford 1983).

Information about conservation actions

There is no strong evidence about the reasons for the decline of the Grasshopper Warbler and, as a result, few specific conservation actions have been proposed to benefit this species. A reduction in suitable scrub habitat is one possible cause (2012): denser, dead vegetation and tussock forming vegetation at ground level; less dense vegetation above 2 m height, soft soil and song posts (see paper for more specific details).