Action Synopsis: Bird Conservation About Actions

Reduce adverse habitat alterations by excluding problematic aquatic species

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

Study locations

Key messages

A replicated paired study in the USA found that waterbirds preferentially used wetland plots from which grass carp Ctenopharyngodon idella were excluded but moved as these became depleted over the winter.


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 replicated, paired study in the winters of 1993-1995 in six sites in an open-water refuge in Alabama, USA (Benedict & Hepp 2000) found that waterbird density in October was higher in plots with grass carp Ctenopharyngodon idella excluded, but that birds moved to plots with carp present over the winter. Exclusion plots had higher levels of native vegetation (dominated by muskgrass Chara spp. and sago pondweed Potamogeton pectinatus) but birds left as this became depleted. Control plots were dominated by (non-native) milfoil Myriophyllum spicatum. Exclusion plots were established to re-establish native species using netting (1.27 cm2 mesh, 1.2 m tall) held in place by buoyant ropes and weighted with steel rods to create 0.1 ha plots (25 x 50 m). Identical plots (without netting) were created (? 25 m away from the native plot) in areas of 100% milfoil coverage.

    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?

List of journals searched by synopsis

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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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