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Providing evidence to improve practice

Action: Increase water turbidity to reduce fish predation by birds Bird Conservation

Key messages

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A randomised trial in France found that little egret Egretta garzetta foraging efficiency was lower in turbid water than clear.


Supporting evidence from individual studies


A randomised trial in southern France found that little egret Egretta garzetta foraging efficiency (capture rate) declined significantly in turbid water, under captive conditions (Cezilly 1992). A 3 x 6 m pool (water depth 10 cm) was used. Nine adult egrets either foraged alone or in threes. Three trials were undertaken using clear or turbid water, with three densities of prey i.e. mosquito fish Gambusia affinis (1, 2, and 4/m²). Treatment order was randomised and trials lasted 5 min. Turbid water was created by adding clay (Secchi disc lost from view at 10 cm depth).


Referenced papers

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. (2019) Bird Conservation. Pages 141-290 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.