Angle windows to reduce collisions by birds

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

60%
Certainty

20%
Harms

0%

Calculating overall effectiveness category

Study locations

Key messages

A single randomised, replicated and controlled experiment in the USA found fewer birds collided with windows angled away from the vertical.

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

A randomised, replicated and controlled experiment in 1991 in Pennsylvania, USA (Klem et al. 2004), found that a fewer birds collided with windows angled at 20^o or 40^o from the vertical (28% and 15% of 53 recorded collisions respectively) than with vertical windows (57% of collisions). Six plate glass, wooden framed windows (1.4 x 1.2 m, 1.2 m off the ground, 15-43 m apart) were used, between January and May, on the edge of deciduous woodland and farmland.
Study and other actions tested
Referenced paper
Klem D. Jr., Keck D.C., Marty K.L., Miller Ball A.J., Niciu E.E. & Platt C.T. (2004) Effects of window angling, feeder placement, and scavengers on avian mortality at plate glass. The Wilson Bulletin, 116, 69-73.

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

This Action forms part of the Action Synopsis:

Bird Conservation

Related Actions

	Actions	Effectiveness	Studies	Category
	Angle windows to reduce collisions by birds Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
	Mark or tint windows to reduce collision mortality Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link