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A review of indirect effects of pesticides on birds and mitigating land-management practices

Tree sparrow perching on branch

Tree sparrow

Many species of farmland birds have shown huge declines in numbers and range over the past four decades. These have been linked to agricultural intensification, which has taken the form of a suite of changes in farming practice, one of which is increased pesticide use. Concern has switched from the direct lethal or sub lethal effects of pesticides to indirect effects. Indirect effects of pesticides act predominantly via reduction in food supplies. This review updates the last review of the indirect effects of pesticides on birds in 2001, and identifies potential measures to mitigate for these effects, such as agri-environment prescriptions.

Project objectives

  • Review current knowledge of indirect effects of pesticides on birds and identify mitigating measures.

Work planned or underway

Four-month project, completed February 2008.


The grey partridge is still the only species for which population level indirect effects of pesticides been demonstrated, via effects on chick survival. Short-term effects of pesticides have been found for corn buntings, but population modelling has not been conducted for this species. Population modelling suggests that suggests that effects of breeding season insecticides on yellowhammer chick condition and brood survival have a relatively small effect on the overall population, with over-winter survival being the current limiting factor for this species. Evidence of effects of pesticides on skylark remains ambiguous. For barn swallow, pesticides do not seem to affect aerial invertebrate food or foraging behaviour, although sample sizes were low.

Most research has focused on effects of pesticides via insect abundance during the breeding season breeding season. However, a recent study showed that over-winter stubbles which followed on from a low-input spring cereal supported higher densities of cirl bunting, yellowhammer and reed bunting.

Linnets and turtle doves have both shown major dietary shifts since the onset of agricultural intensification, switching from predominantly weed seeds to cereal seeds. For linnet, it seems that oil seed rape seed availability has compensated for loss of weed seed in the landscape, as populations are now recovering. However, turtle dove populations continue to decline, and number of nesting attempts per pair have roughly halved since the 1960s. Investigation of effects of herbicides would be valuable for this species.

Research on effects of pesticides on the yellow wagtail would also be valuable, as late in the season its preferred nesting habitat is potatoes, which receive a relatively high number of pesticide applications.

Most research into the indirect effects of pesticides on farmland birds relates to short-term effects of pesticides, but it should also be remembered that the widespread introduction of pesticide use is considered to have caused large-scale losses of seed and invertebrate food over time that will have affected many species of farmland bird.

Agri-environment options that provide alternative food rich habitats on the farm will reduce the effects of pesticides, for example conservation headlands, margins and buffer strips, wild bird seed mixtures, beetle banks, fallow plots, over-winter stubbles, skylark plots and undersown spring cereals.


A review of Indirect Effects of Pesticides on Birds and mitigating land-management practices

A review of Indirect Effects of Pesticides on Birds and mitigating land-management practices

528Kb, PDF

Authors: Bright, J.A., Morris, A.J & Winspear, R. (2007)

Published in: RSPB Research Report 28


Who to contact

Tony Morris
Senior Conservation Scientist


RSPB & The Pesticides Safety Directorate


The Pesticides Safety Directorate