Action: Mow or cut reedbeds
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- 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.
Reedbeds were traditionally cut in much of Europe to provide thatch for housing and this practice continues in some countries. Cutting reeds like this changes the composition of the reedbeds, resulting in higher spring water levels and higher reed biomass (due to increased regrowth) than in uncut reedbeds (Poulin & Lefebvre 2002). A comparison of cut and uncut reedbeds in southern France found that there was also a higher abundance of food arthropods in cut reeds, although lower abundances of birds in summer (Poulin & Lefebvre 2002).
Supporting evidence from individual studies
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.
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%).
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.
- Kristiansen J.N. (1998) Nest site preference by greylag geese Anser anser in reedbeds of different harvest age. Bird Study, 45, 337-343
- Graveland J. (1999) Effects of reed cutting on density and breeding success of reed warbler Acrocephalus scirpacaeus and sedge warbler A. schoenobaenus. Journal of Avian Biology, 30, 469-482
- Gilbert G., Tyler G.A., Dunn C.J., Ratcliffe N. & Smith K.W. (2007) The influence of habitat management on the breeding success of the great bittern Botaurus stellaris in Britain. Ibis, 149, 53-66