Action Synopsis: Bird Conservation About Actions

Use artificial nests that discourage predation

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms
    not assessed

Study locations

Key messages

  • Three trials in North America found lower predation or higher nesting success of wildfowl in nest boxes or nesting ‘tubs’ than natural nests in tree cavities or on the ground.
  • A trial in captivity found that raccoons could be prevented from entering nest boxes if they were topped with a metal cone with a 7.6 cm overhang and the distance between entrance hole and the roof was increased from 30 to 60 cm.
  • A replicated study in the USA found that fewer woods duck Aix sponsa used nest boxes with predator guards on when given the choice of unaltered boxes, but that both designs were used with equal frequency when only one design was available.


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 trial in woodland on Rhode Island, USA, in 1955-56 (Cronan 1957), found that installing predator guards on wood duck Aix sponsa nest boxes reduced the usage of nest boxes, compared to unguarded nest boxes, when birds were given a choice of boxes (55% of 40 boxes with guards used vs. 93% of 40 unguarded boxes). However, in areas where all boxes were either guarded or unguarded, there was no significant difference in usage (51% of 55 guarded nests used vs. 56% of 52 unguarded). This study is also discussed in ‘Provide artificial nesting sites’.

    Study and other actions tested
  2. A before-and-after study on a marshland site in Montana, USA (Craighead & Stockstad 1961), found that Canada goose Branta canadensis nests on raised artificial nesting platforms were significantly less likely to be predated than the population average (7% of 14 failed platform nests predated vs. population average of 61% of 404 failed nests). This study is discussed in detail in ‘Provide artificial nest sites’.

    Study and other actions tested
  3. A replicated, controlled study from 1958-1961 in multiple woodlots in Illinois, USA (Bellrose et al. 1964) found that wood ducks Aix sponsa had higher nesting success in nest boxes, compared to natural cavities (71% success for 574 metal nest boxes vs. 37% for 116 natural cavities). As racoon Procyon lotor predation accounted for most nest loss, the authors conclude that metal nest boxes provided some protection from predation. This study is also discussed in ‘Provide artificial nest sites’.

    Study and other actions tested
  4. A replicated study on a wetland site in Missouri, USA (Brakhage 1966), found that 2% of 268 Canada goose Branta canadensis clutches in artificial nest ‘tubs’ were predated in 1962-5, compared 32% of 106 clutches laid on the ground. Artificial nests consisted of ‘No. 2 round washtubs’ placed in trees, on fence posts or specially constructed stands and partially filled with sawdust and straw to allow geese to bury unattended eggs. Tubs were placed 1-20 m off the ground (height did not affect predation rate). Some nests were still considered useable after nine years.

    Study and other actions tested
  5. A trial in captivity in Illinois, USA, in the 1960s (Eaton 1966) found that raccoons Procyon lotor could enter metal wood duck Aix sponsa houses (cylindrical metal houses with a 33 cm cone on top and a 10 cm circular entrance hole) more easily if the cone on top of the house was increased beyond the standard 33 cm. However, if the cone was extended to provide a 7.6 cm overhanging roof and the distance between entrance hole and the roof was increased from 30 to 60 cm, then none of the five raccoons tested could access the nest hole. Reducing the size of the entrance hole to 8.9 x 7 cm also prevented all raccoons from entering, but the authors warn that it is not certain whether wood ducks would use such entrances.

    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
What Works 2021 cover

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.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust