Action Synopsis: Bird Conservation About Actions

Replace nesting substrate following severe weather

How is the evidence assessed?

Study locations

Key messages

Two before-and-after studies from Canada found that common tern Sterna hirundo populations increased at one colony where nesting substrates were replaced, but decreased at a second. Several other interventions were used at both sites, making it difficult to evaluate the effects of substrate replacement.


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. Two before-and-after studies at two common tern Sterna hirundo colonies between 1977-89 in Ontario, Canada (Morris et al. 1992), found the nesting population increased at one colony but decreased at another following a combination of interventions, including the replacement of nesting substrate following flooding. Other interventions included: erecting signs highlighting the presence of nesting birds, vegetation control, preventing gulls Larus spp. from nesting, destroying gull nests and shooting particular ring-billed gulls L. delawarensis that were heavily predating tern eggs. Gulls were only culled at the site with population increase, whilst the authors attribute declines to continued high levels of disturbance, vegetation growth and mammalian predators.

    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

All the journals searched for all synopses

Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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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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