Action Synopsis: Bird Conservation About Actions

Mow or cut reedbeds

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • Of three studies captured, one controlled study from the Netherlands found that warblers nested at lower densities in cut areas of reeds. Productivity and success did not vary between treatments.
  • An unreplicated study from Denmark found that geese grazed at the highest densities on reedbeds cut 5–12 years previously.
  • One replicated study investigated changing water levels in addition to cutting reeds in the UK and found that management did not affect great bittern breeding productivity but did appear to delay territory establishment.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A site comparison study in two wetland sites in Vejlerne, a wetland in North Jutland, Denmark (Kristiansen 1998), found that the highest densities of greylag geese Anser anser nests were found in reedbeds that were cut between five and eleven or five and 12 years before (3.1-3.4 nests/ha). No nests were found in beds cut that year and very few (and only in one site) in beds cut less than three years (fewer than 0.7 nests/ha) or more than eleven years before. The authors speculate that geese need an intermediate density of reed stems to nest effectively.

    Study and other actions tested
  2. A controlled study in 1993-1995 in an area of peat marsh in Overijssel, the Netherlands (Graveland 1999), found that reed warblers Acrocephalus scirpaceus and sedge warblers A. schoenobaenus nested at significantly lower densities in areas of recently cut reedbed, compared to uncut areas (reed warblers: 0.8 nests/100 m of shore for cut areas vs. 2.0 nests/100 m for uncut; sedge warblers: 0.03 nests/100 m vs. 0.7 nests/100 m). There were no significant difference in the fledging success of unpredated nests in cut and uncut reed, but nest predation of reed warblers was higher in cut reed (33% predated in cut areas vs. 17% in uncut areas). There was no difference for sedge warblers (73% vs. 43%).

    Study and other actions tested
  3. A replicated study in 1997-2001 in ten reedbed sites across England (Gilbert et al. 2007) investigated the impact of raising water levels in reedbeds on great bittern Botaurus stellaris breeding (see ‘Manage water levels in wetlands’). Reeds at sites with low water levels were cut in spring (March-April), compared with winter (completed by December) for high water level sites, but the effect of cutting was not specifically investigated. Male bitterns at low-water sites established territories later than on high-water sites, but sites did not differ in productivity.

    Study and other actions tested
Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

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Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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