Action Synopsis: Bird Conservation About Actions

Provide artificial nesting sites for rollers

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

Study locations

Key messages

  • A before-and-after study from Spain found that the use of nest boxes by European rollers Coracias garrulous increased over time and that use varied between habitats.
  • A replicated controlled trial from Spain found no difference in success rates between new and old nest boxes, although birds in old boxes began nesting earlier.


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 in pastureland in 1989-90 in Extramadura, Spain (Avilés et al. 2000), found that European rollers Coracias garrulus nesting in new nest boxes did not have higher reproductive success than those nesting in older nest boxes (average of 4.3 eggs/clutch, 69% breeding success and 4.0 fledglings/successful nest for 16 pairs in old boxes vs. 4.1 eggs/clutch, 83% and 3.6 fledglings/nest for 49 pairs in new boxes) and began laying significantly later (average laying date of 25th May for clutches in 16 old boxes vs. 30th May for 49 new boxes). Rollers did not appear to preferentially use either old or new boxes. Boxes were 32 x 18 x 19 cm with a 6 x 18 cm entrance hole and were installed on power line pylons at an average density of 9.5 boxes/km of power line.

    Study and other actions tested
  2. A before-and-after study in agricultural habitats in Extramadura, Spain (Avilés & Parejo 2004), found that the number of European rollers Coracias garrulus using artificial nest boxes increased from 29 in 1988 (76% of the 38 boxes available) to 350 in 1991 (55% of 641 available boxes). Nest boxes use varied with habitat: from 68% use in unwooded pasture (256 boxes available) to only 34% in cereal fields with holm oaks (32 boxes). Nest boxes were the same design as in Avilés et al. 2000.

    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