Install acoustic wildlife warnings along roads

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
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How is the evidence assessed?

Effectiveness

5%
Certainty

37%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Collisions with vehicles can be a major cause of mortality for wild mammals and, especially where larger mammal species are involved, a cause of injury, death and economic loss for motorists (Conover et al. 1995). A range of interventions may be employed to deter mammals for accessing roads. This can include use of acoustic warnings which can either be devices that emit sounds or modifications to the road surface that produce noise when vehicle tyres pass over them.

Conover M.R., Pitt W.C., Kessler K.K., DuBow T.J. & Sanborn W.A. (1995) Review of human injuries, illnesses, and economic losses caused by wildlife in the United States. Wildlife Society Bulletin, 23, 407–414.

Study locations

Key messages

Two studies evaluated the effects on mammals of installing acoustic wildlife warnings along roads. One study was in Demark and one was in Australia.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (2 STUDIES)

Behaviour change (2 studies): A before-and-after study in Denmark found that sound from acoustic road markings did not alter fallow deer behaviour. A controlled study in Australia found that Roo-Guard® sound emitters did not deter tammar wallabies from food and so were not considered suitable for keeping them off roads.

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 before-and-after study in 1997 in a mixed hardwood forest in Zealand, Denmark (Ujvári et al. 2004) found that acoustic road markings did not alter the behaviour of fallow deer Dama dama. Behavioural responses varied among nights, but deer showed increasing indifference to sounds from road markings over 11 nights (i.e. deer appeared to become habituated). Behaviour differed before (flight: 2%, no reaction: 96–99%) and during playbacks, but deer reactions declined over 10 nights of playbacks (night 1: flight 13%; nights 8–10: flight 3–0%, no reaction 88–99%). An area of forest next to an unpaved road closed to vehicles was selected where a herd of 6–12 fallow deer were fed (maize). Recordings of a car passing two types of acoustic road markings which produced sounds when a vehicle’s tyres passed over (low frequency longflex; higher spossflex), multiplied to 70 sequences (each 0.11–0.16 s) were made. Behavioural responses of deer to play-back sounds (58 decibels) at predetermined time intervals (exposure for: 5, 2, 7, 3, 1 and 2 minutes) were monitored over 11 nights in February–March 1997. Behaviour was also recorded every 15 minutes during the two nights before sound trials commenced.
Study and other actions tested
Referenced paper
Ujvári M., Baagøe H.J. & Madsen A.B. (2004) Effectiveness of acoustic road markings in reducing deer-vehicle collisions: a behavioural study. Wildlife Biology, 10, 155-159.
A controlled study in 2005 in a grass enclosure in Western Australia, Australia (Muirhead et al. 2006) found that Roo-Guard® sound emitters did not deter tammar wallabies Macropus eugenii from food and so were not considered suitable for keeping them off roads. There was no significant difference between the use of the enclosure or food sources when the Roo-Guards were switched on or off. This was the case even when there was an alternative source of food available away from Roo-Guards. The device did not result in any obvious behavioural responses such as flight or distress. Nine tammars were kept in an enclosure (60 × 30 m), with a test area (60 × 20 m) divided into 12 squares. The remainder of the enclosure was covered in trees and bushes. Roo-Guard® Mk II high-frequency sound emitters were installed on the edge of the test area, 0.5 m off the ground. Animals were observed though a night-vision scope on three nights (18:00–21:00 h) with the Roo-Guard turned on and three with it turned off, for each of four treatments: food 20 m from Roo-Guard, or food 20 and 60 m from Roo-Guard, and the same two treatments but with the sides with food and Roo-Guards swapped over.
Study and other actions tested
Referenced paper
Muirhead S., Blache D., Wykes B. & Bencini R. (2006) Roo-Guard® sound emitters are not effective at deterring tammar wallabies (Macropus eugenii) from a source of food. Wildlife Research, 33, 131-136.

Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Terrestrial Mammal Conservation

Related Actions

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Install wildlife warning reflectors along roads Action Link	Likely to be beneficial	15	Synopsis Link
Install wildlife exclusion grates/cattle grids Action Link	Likely to be beneficial	3	Synopsis Link
Use wildlife decoy to reduce vehicle collisions with mammals Action Link	No evidence found (no assessment)	0	Synopsis Link