Action Synopsis: Bird Conservation About Actions

Relocate nests at harvest time to reduce nestling mortality

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

Study locations

Key messages

A replicated controlled study from Spain found that clutches that were temporarily removed from fields during harvest and then replaced had higher hatching and fledging rates than control clutches. Effects were greater on clutches that were older when moved.


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, controlled study from 1987-91 in five areas of cereal fields in southwest Spain (Corbacho et al. 1999) found that nestling mortality of Montagu’s harriers Circus pygarus was significantly lower, and fledging success significantly higher, for clutches that were removed from fields before harvesting, and returned within an hour, compared to control (unmoved) clutches (28% mortality  and 75% of nests fledging at least one chick in 72 managed clutches vs. 67% mortality and 29% fledging success in 39 controls).  Outcome was highly dependent on clutch age at time of harvest:  no clutches less than ten days old at harvest fledged young, whilst nest management increased the proportion of successful clutches aged 11-20 days at harvesting from 14% to 75%. The average harvest date of barley fields was later than for wheat or oat fields, but the small number of clutches (13) in barley fields made it impossible to assess the influence of nesting habitat on unmanaged clutch success.  The nature of the crop (wheat and/or oat vs. barley) did not influence breeding success in managed clutches.

    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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